From 205897101ff43a5c1e2a6285c4d93e735c2b01a0 Mon Sep 17 00:00:00 2001
From: "Johan B.W. de Vries" <info@jbwdevries.nl>
Date: Fri, 16 Sep 2022 14:42:40 +0200
Subject: [PATCH] Adds a typing system to Phasm

---
 Makefile                                      |   5 +-
 README.md                                     |   4 +-
 TODO.md                                       |   3 +-
 examples/buffer.py                            |   2 +-
 phasm/__main__.py                             |   2 +
 phasm/codestyle.py                            | 144 ++---
 phasm/compiler.py                             | 527 ++++++++++------
 phasm/ourlang.py                              | 343 ++++-------
 phasm/parser.py                               | 520 +++++-----------
 phasm/stdlib/alloc.py                         |   2 +-
 phasm/type3/__init__.py                       |   0
 phasm/type3/constraints.py                    | 549 +++++++++++++++++
 phasm/type3/constraintsgenerator.py           | 219 +++++++
 phasm/type3/entry.py                          | 154 +++++
 phasm/type3/types.py                          | 322 ++++++++++
 phasm/typing.py                               | 202 -------
 phasm/wasmeasy.py                             |  69 ---
 pylintrc                                      |   4 +-
 requirements.txt                              |   8 +-
 tests/integration/constants.py                |  16 +
 tests/integration/helpers.py                  |   4 +-
 tests/integration/runners.py                  |   4 +-
 tests/integration/test_constants.py           |  87 ---
 tests/integration/test_examples/__init__.py   |   0
 .../integration/test_examples/test_buffer.py  |  19 +
 .../test_crc32.py}                            |   4 +-
 tests/integration/test_examples/test_fib.py   |  12 +
 tests/integration/test_fib.py                 |  30 -
 tests/integration/test_helper.py              |  70 ---
 tests/integration/test_lang/__init__.py       |   0
 .../{ => test_lang}/test_builtins.py          |   4 +-
 tests/integration/test_lang/test_bytes.py     |  84 +++
 tests/integration/test_lang/test_if.py        |  71 +++
 tests/integration/test_lang/test_interface.py |  79 +++
 .../integration/test_lang/test_primitives.py  | 486 +++++++++++++++
 .../test_lang/test_static_array.py            | 195 ++++++
 tests/integration/test_lang/test_struct.py    | 154 +++++
 tests/integration/test_lang/test_tuple.py     | 188 ++++++
 tests/integration/test_runtime_checks.py      |  31 -
 tests/integration/test_simple.py              | 571 ------------------
 tests/integration/test_static_checking.py     | 109 ----
 tests/integration/test_stdlib/__init__.py     |   0
 .../test_alloc.py}                            |   4 +-
 43 files changed, 3249 insertions(+), 2052 deletions(-)
 create mode 100644 phasm/type3/__init__.py
 create mode 100644 phasm/type3/constraints.py
 create mode 100644 phasm/type3/constraintsgenerator.py
 create mode 100644 phasm/type3/entry.py
 create mode 100644 phasm/type3/types.py
 delete mode 100644 phasm/typing.py
 delete mode 100644 phasm/wasmeasy.py
 create mode 100644 tests/integration/constants.py
 delete mode 100644 tests/integration/test_constants.py
 create mode 100644 tests/integration/test_examples/__init__.py
 create mode 100644 tests/integration/test_examples/test_buffer.py
 rename tests/integration/{test_examples.py => test_examples/test_crc32.py} (93%)
 create mode 100644 tests/integration/test_examples/test_fib.py
 delete mode 100644 tests/integration/test_fib.py
 delete mode 100644 tests/integration/test_helper.py
 create mode 100644 tests/integration/test_lang/__init__.py
 rename tests/integration/{ => test_lang}/test_builtins.py (95%)
 create mode 100644 tests/integration/test_lang/test_bytes.py
 create mode 100644 tests/integration/test_lang/test_if.py
 create mode 100644 tests/integration/test_lang/test_interface.py
 create mode 100644 tests/integration/test_lang/test_primitives.py
 create mode 100644 tests/integration/test_lang/test_static_array.py
 create mode 100644 tests/integration/test_lang/test_struct.py
 create mode 100644 tests/integration/test_lang/test_tuple.py
 delete mode 100644 tests/integration/test_runtime_checks.py
 delete mode 100644 tests/integration/test_simple.py
 delete mode 100644 tests/integration/test_static_checking.py
 create mode 100644 tests/integration/test_stdlib/__init__.py
 rename tests/integration/{test_stdlib_alloc.py => test_stdlib/test_alloc.py} (95%)

diff --git a/Makefile b/Makefile
index ad186c2..ac1bf09 100644
--- a/Makefile
+++ b/Makefile
@@ -34,11 +34,14 @@ typecheck: venv/.done
 	venv/bin/mypy --strict phasm tests/integration/runners.py
 
 venv/.done: requirements.txt
-	python3.8 -m venv venv
+	python3.10 -m venv venv
 	venv/bin/python3 -m pip install wheel pip --upgrade
 	venv/bin/python3 -m pip install -r $^
 	touch $@
 
+clean-examples:
+	rm -f examples/*.wat examples/*.wasm examples/*.wat.html examples/*.py.html
+
 .SECONDARY: # Keep intermediate files
 
 .PHONY: examples
diff --git a/README.md b/README.md
index c9cb056..a5af8d8 100644
--- a/README.md
+++ b/README.md
@@ -12,7 +12,7 @@ This is a hobby project for now. Use at your own risk.
 
 How to run
 ----------
-You should only need make and python3. Currently, we're working with python3.8,
+You should only need make and python3. Currently, we're working with python3.10,
 since we're using the python ast parser, it might not work on other versions.
 
 To run the examples:
@@ -32,7 +32,7 @@ make lint typecheck
 
 To compile a Phasm file:
 ```sh
-python3.8 -m phasm source.py output.wat
+python3.10 -m phasm source.py output.wat
 ```
 
 Additional required tools
diff --git a/TODO.md b/TODO.md
index 0da4619..212fbd0 100644
--- a/TODO.md
+++ b/TODO.md
@@ -1,7 +1,8 @@
 # TODO
 
+- Rename constant to literal
+
 - Implement a trace() builtin for debugging
-- Implement a proper type matching / checking system
 - Check if we can use DataView in the Javascript examples, e.g. with setUint32
 - Storing u8 in memory still claims 32 bits (since that's what you need in local variables). However, using load8_u / loadu_s we can optimize this.
 - Implement a FizzBuzz example
diff --git a/examples/buffer.py b/examples/buffer.py
index 6f251ff..8fe6570 100644
--- a/examples/buffer.py
+++ b/examples/buffer.py
@@ -3,5 +3,5 @@ def index(inp: bytes, idx: u32) -> u8:
     return inp[idx]
 
 @exported
-def length(inp: bytes) -> i32:
+def length(inp: bytes) -> u32:
     return len(inp)
diff --git a/phasm/__main__.py b/phasm/__main__.py
index bc94cdb..97615e0 100644
--- a/phasm/__main__.py
+++ b/phasm/__main__.py
@@ -5,6 +5,7 @@ Functions for using this module from CLI
 import sys
 
 from .parser import phasm_parse
+from .type3.entry import phasm_type3
 from .compiler import phasm_compile
 
 def main(source: str, sink: str) -> int:
@@ -16,6 +17,7 @@ def main(source: str, sink: str) -> int:
         code_py = fil.read()
 
     our_module = phasm_parse(code_py)
+    phasm_type3(our_module, verbose=False)
     wasm_module = phasm_compile(our_module)
     code_wat = wasm_module.to_wat()
 
diff --git a/phasm/codestyle.py b/phasm/codestyle.py
index 4b38e32..c984937 100644
--- a/phasm/codestyle.py
+++ b/phasm/codestyle.py
@@ -6,7 +6,8 @@ It's intented to be a "any color, as long as it's black" kind of renderer
 from typing import Generator
 
 from . import ourlang
-from . import typing
+from .type3 import types as type3types
+from .type3.types import TYPE3_ASSERTION_ERROR, Type3, Type3OrPlaceholder
 
 def phasm_render(inp: ourlang.Module) -> str:
     """
@@ -16,63 +17,39 @@ def phasm_render(inp: ourlang.Module) -> str:
 
 Statements = Generator[str, None, None]
 
-def type_(inp: typing.TypeBase) -> str:
+def type3(inp: Type3OrPlaceholder) -> str:
     """
-    Render: Type (name)
+    Render: type's name
     """
-    if isinstance(inp, typing.TypeNone):
+    assert isinstance(inp, Type3), TYPE3_ASSERTION_ERROR
+
+    if inp is type3types.none:
         return 'None'
 
-    if isinstance(inp, typing.TypeBool):
-        return 'bool'
+    if isinstance(inp, type3types.AppliedType3):
+        if inp.base == type3types.tuple:
+            return '(' + ', '.join(
+                type3(x)
+                for x in inp.args
+                if isinstance(x, Type3) # Skip ints, not allowed here anyhow
+            ) + ', )'
 
-    if isinstance(inp, typing.TypeUInt8):
-        return 'u8'
+        if inp.base == type3types.static_array:
+            assert 2 == len(inp.args)
+            assert isinstance(inp.args[0], Type3), TYPE3_ASSERTION_ERROR
+            assert isinstance(inp.args[1], type3types.IntType3), TYPE3_ASSERTION_ERROR
 
-    if isinstance(inp, typing.TypeUInt32):
-        return 'u32'
+            return inp.args[0].name + '[' + inp.args[1].name + ']'
 
-    if isinstance(inp, typing.TypeUInt64):
-        return 'u64'
+    return inp.name
 
-    if isinstance(inp, typing.TypeInt32):
-        return 'i32'
-
-    if isinstance(inp, typing.TypeInt64):
-        return 'i64'
-
-    if isinstance(inp, typing.TypeFloat32):
-        return 'f32'
-
-    if isinstance(inp, typing.TypeFloat64):
-        return 'f64'
-
-    if isinstance(inp, typing.TypeBytes):
-        return 'bytes'
-
-    if isinstance(inp, typing.TypeTuple):
-        mems = ', '.join(
-            type_(x.type)
-            for x in inp.members
-        )
-
-        return f'({mems}, )'
-
-    if isinstance(inp, typing.TypeStaticArray):
-        return f'{type_(inp.member_type)}[{len(inp.members)}]'
-
-    if isinstance(inp, typing.TypeStruct):
-        return inp.name
-
-    raise NotImplementedError(type_, inp)
-
-def struct_definition(inp: typing.TypeStruct) -> str:
+def struct_definition(inp: ourlang.StructDefinition) -> str:
     """
     Render: TypeStruct's definition
     """
-    result = f'class {inp.name}:\n'
-    for mem in inp.members:
-        result += f'    {mem.name}: {type_(mem.type)}\n'
+    result = f'class {inp.struct_type3.name}:\n'
+    for mem, typ in inp.struct_type3.members.items():
+        result += f'    {mem}: {type3(typ)}\n'
 
     return result
 
@@ -80,40 +57,44 @@ def constant_definition(inp: ourlang.ModuleConstantDef) -> str:
     """
     Render: Module Constant's  definition
     """
-    return f'{inp.name}: {type_(inp.type)} = {expression(inp.constant)}\n'
+    return f'{inp.name}: {type3(inp.type3)} = {expression(inp.constant)}\n'
 
 def expression(inp: ourlang.Expression) -> str:
     """
     Render: A Phasm expression
     """
-    if isinstance(inp, (
-            ourlang.ConstantUInt8, ourlang.ConstantUInt32, ourlang.ConstantUInt64,
-            ourlang.ConstantInt32, ourlang.ConstantInt64,
-        )):
-        return str(inp.value)
-
-    if isinstance(inp, (ourlang.ConstantFloat32, ourlang.ConstantFloat64, )):
-        # These might not round trip if the original constant
+    if isinstance(inp, ourlang.ConstantPrimitive):
+        # Floats might not round trip if the original constant
         # could not fit in the given float type
         return str(inp.value)
 
-    if isinstance(inp, (ourlang.ConstantTuple, ourlang.ConstantStaticArray, )):
+    if isinstance(inp, ourlang.ConstantTuple):
         return '(' + ', '.join(
             expression(x)
             for x in inp.value
         ) + ', )'
 
+    if isinstance(inp, ourlang.ConstantStruct):
+        return inp.struct_name + '(' + ', '.join(
+            expression(x)
+            for x in inp.value
+        ) + ')'
+
     if isinstance(inp, ourlang.VariableReference):
-        return str(inp.name)
+        return str(inp.variable.name)
 
     if isinstance(inp, ourlang.UnaryOp):
         if (
-            inp.operator in ourlang.WEBASSEMBLY_BUILDIN_FLOAT_OPS
-            or inp.operator in ourlang.WEBASSEMBLY_BUILDIN_BYTES_OPS):
+            inp.operator in ourlang.WEBASSEMBLY_BUILTIN_FLOAT_OPS
+            or inp.operator in ourlang.WEBASSEMBLY_BUILTIN_BYTES_OPS):
             return f'{inp.operator}({expression(inp.right)})'
 
         if inp.operator == 'cast':
-            return f'{type_(inp.type)}({expression(inp.right)})'
+            mtyp = type3(inp.type3)
+            if mtyp is None:
+                raise NotImplementedError(f'Casting to type {inp.type_var}')
+
+            return f'{mtyp}({expression(inp.right)})'
 
         return f'{inp.operator}{expression(inp.right)}'
 
@@ -127,32 +108,31 @@ def expression(inp: ourlang.Expression) -> str:
         )
 
         if isinstance(inp.function, ourlang.StructConstructor):
-            return f'{inp.function.struct.name}({args})'
-
-        if isinstance(inp.function, ourlang.TupleConstructor):
-            return f'({args}, )'
+            return f'{inp.function.struct_type3.name}({args})'
 
         return f'{inp.function.name}({args})'
 
-    if isinstance(inp, ourlang.AccessBytesIndex):
-        return f'{expression(inp.varref)}[{expression(inp.index)}]'
+    if isinstance(inp, ourlang.TupleInstantiation):
+        args = ', '.join(
+            expression(arg)
+            for arg in inp.elements
+        )
+
+        return f'({args}, )'
+
+    if isinstance(inp, ourlang.Subscript):
+        varref = expression(inp.varref)
+        index = expression(inp.index)
+
+        return f'{varref}[{index}]'
 
     if isinstance(inp, ourlang.AccessStructMember):
-        return f'{expression(inp.varref)}.{inp.member.name}'
-
-    if isinstance(inp, (ourlang.AccessTupleMember, ourlang.AccessStaticArrayMember, )):
-        if isinstance(inp.member, ourlang.Expression):
-            return f'{expression(inp.varref)}[{expression(inp.member)}]'
-
-        return f'{expression(inp.varref)}[{inp.member.idx}]'
+        return f'{expression(inp.varref)}.{inp.member}'
 
     if isinstance(inp, ourlang.Fold):
         fold_name = 'foldl' if ourlang.Fold.Direction.LEFT == inp.dir else 'foldr'
         return f'{fold_name}({inp.func.name}, {expression(inp.base)}, {expression(inp.iter)})'
 
-    if isinstance(inp, ourlang.ModuleConstantReference):
-        return inp.definition.name
-
     raise NotImplementedError(expression, inp)
 
 def statement(inp: ourlang.Statement) -> Statements:
@@ -193,11 +173,11 @@ def function(inp: ourlang.Function) -> str:
         result += '@imported\n'
 
     args = ', '.join(
-        f'{x}: {type_(y)}'
-        for x, y in inp.posonlyargs
+        f'{p.name}: {type3(p.type3)}'
+        for p in inp.posonlyargs
     )
 
-    result += f'def {inp.name}({args}) -> {type_(inp.returns)}:\n'
+    result += f'def {inp.name}({args}) -> {type3(inp.returns_type3)}:\n'
 
     if inp.imported:
         result += '    pass\n'
@@ -215,7 +195,7 @@ def module(inp: ourlang.Module) -> str:
     """
     result = ''
 
-    for struct in inp.structs.values():
+    for struct in inp.struct_definitions.values():
         if result:
             result += '\n'
         result += struct_definition(struct)
@@ -227,7 +207,7 @@ def module(inp: ourlang.Module) -> str:
 
     for func in inp.functions.values():
         if func.lineno < 0:
-            # Buildin (-2) or auto generated (-1)
+            # Builtin (-2) or auto generated (-1)
             continue
 
         if result:
diff --git a/phasm/compiler.py b/phasm/compiler.py
index 4ba5d5a..c2bbad1 100644
--- a/phasm/compiler.py
+++ b/phasm/compiler.py
@@ -1,11 +1,13 @@
 """
 This module contains the code to convert parsed Ourlang into WebAssembly code
 """
+from typing import List, Union
+
 import struct
 
 from . import codestyle
 from . import ourlang
-from . import typing
+from .type3 import types as type3types
 from . import wasm
 
 from .stdlib import alloc as stdlib_alloc
@@ -13,17 +15,14 @@ from .stdlib import types as stdlib_types
 from .wasmgenerator import Generator as WasmGenerator
 
 LOAD_STORE_TYPE_MAP = {
-    typing.TypeUInt8: 'i32',
-    typing.TypeUInt32: 'i32',
-    typing.TypeUInt64: 'i64',
-    typing.TypeInt32: 'i32',
-    typing.TypeInt64: 'i64',
-    typing.TypeFloat32: 'f32',
-    typing.TypeFloat64: 'f64',
+    'u8': 'i32', # Have to use an u32, since there is no native u8 type
+    'i32': 'i32',
+    'i64': 'i64',
+    'u32': 'i32',
+    'u64': 'i64',
+    'f32': 'f32',
+    'f64': 'f64',
 }
-"""
-When generating code, we sometimes need to load or store simple values
-"""
 
 def phasm_compile(inp: ourlang.Module) -> wasm.Module:
     """
@@ -32,42 +31,60 @@ def phasm_compile(inp: ourlang.Module) -> wasm.Module:
     """
     return module(inp)
 
-def type_(inp: typing.TypeBase) -> wasm.WasmType:
+def type3(inp: type3types.Type3OrPlaceholder) -> wasm.WasmType:
     """
     Compile: type
+
+    Types are used for example in WebAssembly function parameters
+    and return types.
     """
-    if isinstance(inp, typing.TypeNone):
+    assert isinstance(inp, type3types.Type3), type3types.TYPE3_ASSERTION_ERROR
+
+    if inp == type3types.none:
         return wasm.WasmTypeNone()
 
-    if isinstance(inp, typing.TypeUInt8):
+    if inp == type3types.u8:
         # WebAssembly has only support for 32 and 64 bits
         # So we need to store more memory per byte
         return wasm.WasmTypeInt32()
 
-    if isinstance(inp, typing.TypeUInt32):
+    if inp == type3types.u32:
         return wasm.WasmTypeInt32()
 
-    if isinstance(inp, typing.TypeUInt64):
+    if inp == type3types.u64:
         return wasm.WasmTypeInt64()
 
-    if isinstance(inp, typing.TypeInt32):
+    if inp == type3types.i32:
         return wasm.WasmTypeInt32()
 
-    if isinstance(inp, typing.TypeInt64):
+    if inp == type3types.i64:
         return wasm.WasmTypeInt64()
 
-    if isinstance(inp, typing.TypeFloat32):
+    if inp == type3types.f32:
         return wasm.WasmTypeFloat32()
 
-    if isinstance(inp, typing.TypeFloat64):
+    if inp == type3types.f64:
         return wasm.WasmTypeFloat64()
 
-    if isinstance(inp, (typing.TypeStruct, typing.TypeTuple, typing.TypeStaticArray, typing.TypeBytes)):
-        # Structs and tuples are passed as pointer
+    if inp == type3types.bytes:
+        # bytes are passed as pointer
         # And pointers are i32
         return wasm.WasmTypeInt32()
 
-    raise NotImplementedError(type_, inp)
+    if isinstance(inp, type3types.StructType3):
+        # Structs are passed as pointer, which are i32
+        return wasm.WasmTypeInt32()
+
+    if isinstance(inp, type3types.AppliedType3):
+        if inp.base == type3types.static_array:
+            # Static Arrays are passed as pointer, which are i32
+            return wasm.WasmTypeInt32()
+
+        if inp.base == type3types.tuple:
+            # Tuples are passed as pointer, which are i32
+            return wasm.WasmTypeInt32()
+
+    raise NotImplementedError(type3, inp)
 
 # Operators that work for i32, i64, f32, f64
 OPERATOR_MAP = {
@@ -81,8 +98,6 @@ U8_OPERATOR_MAP = {
     # Under the hood, this is an i32
     # Implementing Right Shift XOR, OR, AND is fine since the 3 remaining
     # bytes stay zero after this operation
-    # Since it's unsigned an unsigned value, Logical or Arithmetic shift right
-    # are the same operation
     '>>': 'shr_u',
     '^': 'xor',
     '|': 'or',
@@ -99,6 +114,7 @@ U32_OPERATOR_MAP = {
     '^': 'xor',
     '|': 'or',
     '&': 'and',
+    '/': 'div_u' # Division by zero is a trap and the program will panic
 }
 
 U64_OPERATOR_MAP = {
@@ -111,6 +127,7 @@ U64_OPERATOR_MAP = {
     '^': 'xor',
     '|': 'or',
     '&': 'and',
+    '/': 'div_u' # Division by zero is a trap and the program will panic
 }
 
 I32_OPERATOR_MAP = {
@@ -118,6 +135,7 @@ I32_OPERATOR_MAP = {
     '>': 'gt_s',
     '<=': 'le_s',
     '>=': 'ge_s',
+    '/': 'div_s' # Division by zero is a trap and the program will panic
 }
 
 I64_OPERATOR_MAP = {
@@ -125,115 +143,226 @@ I64_OPERATOR_MAP = {
     '>': 'gt_s',
     '<=': 'le_s',
     '>=': 'ge_s',
+    '/': 'div_s' # Division by zero is a trap and the program will panic
 }
 
+F32_OPERATOR_MAP = {
+    '/': 'div' # Division by zero is a trap and the program will panic
+}
+
+F64_OPERATOR_MAP = {
+    '/': 'div' # Division by zero is a trap and the program will panic
+}
+
+def tuple_instantiation(wgn: WasmGenerator, inp: ourlang.TupleInstantiation) -> None:
+    """
+    Compile: Instantiation (allocation) of a tuple
+    """
+    assert isinstance(inp.type3, type3types.AppliedType3)
+    assert inp.type3.base is type3types.tuple
+    assert len(inp.elements) == len(inp.type3.args)
+
+    comment_elements = ''
+    for element in inp.elements:
+        assert isinstance(element.type3, type3types.Type3), type3types.TYPE3_ASSERTION_ERROR
+        comment_elements += f'{element.type3.name}, '
+
+    tmp_var = wgn.temp_var_i32('tuple_adr')
+    wgn.add_statement('nop', comment=f'{tmp_var.name} := ({comment_elements})')
+
+    # Allocated the required amounts of bytes in memory
+    wgn.i32.const(_calculate_alloc_size(inp.type3))
+    wgn.call(stdlib_alloc.__alloc__)
+    wgn.local.set(tmp_var)
+
+    # Store each element individually
+    offset = 0
+    for element, exp_type3 in zip(inp.elements, inp.type3.args):
+        if isinstance(exp_type3, type3types.PlaceholderForType):
+            assert exp_type3.resolve_as is not None
+            exp_type3 = exp_type3.resolve_as
+
+        assert element.type3 == exp_type3
+
+        assert isinstance(exp_type3, type3types.PrimitiveType3), NotImplementedError('Tuple of applied types / structs')
+        mtyp = LOAD_STORE_TYPE_MAP[exp_type3.name]
+
+        wgn.local.get(tmp_var)
+        expression(wgn, element)
+        wgn.add_statement(f'{mtyp}.store', 'offset=' + str(offset))
+
+        offset += _calculate_alloc_size(exp_type3)
+
+    # Return the allocated address
+    wgn.local.get(tmp_var)
+
 def expression(wgn: WasmGenerator, inp: ourlang.Expression) -> None:
     """
     Compile: Any expression
     """
-    if isinstance(inp, ourlang.ConstantUInt8):
-        wgn.i32.const(inp.value)
-        return
+    if isinstance(inp, ourlang.ConstantPrimitive):
+        assert isinstance(inp.type3, type3types.Type3), type3types.TYPE3_ASSERTION_ERROR
 
-    if isinstance(inp, ourlang.ConstantUInt32):
-        wgn.i32.const(inp.value)
-        return
+        if inp.type3 == type3types.u8:
+            # No native u8 type - treat as i32, with caution
+            assert isinstance(inp.value, int)
+            wgn.i32.const(inp.value)
+            return
 
-    if isinstance(inp, ourlang.ConstantUInt64):
-        wgn.i64.const(inp.value)
-        return
+        if inp.type3 in (type3types.i32, type3types.u32, ):
+            assert isinstance(inp.value, int)
+            wgn.i32.const(inp.value)
+            return
 
-    if isinstance(inp, ourlang.ConstantInt32):
-        wgn.i32.const(inp.value)
-        return
+        if inp.type3 in (type3types.i64, type3types.u64, ):
+            assert isinstance(inp.value, int)
+            wgn.i64.const(inp.value)
+            return
 
-    if isinstance(inp, ourlang.ConstantInt64):
-        wgn.i64.const(inp.value)
-        return
+        if inp.type3 == type3types.f32:
+            assert isinstance(inp.value, float)
+            wgn.f32.const(inp.value)
+            return
 
-    if isinstance(inp, ourlang.ConstantFloat32):
-        wgn.f32.const(inp.value)
-        return
+        if inp.type3 == type3types.f64:
+            assert isinstance(inp.value, float)
+            wgn.f64.const(inp.value)
+            return
 
-    if isinstance(inp, ourlang.ConstantFloat64):
-        wgn.f64.const(inp.value)
-        return
+        raise NotImplementedError(f'Constants with type {inp.type3}')
 
     if isinstance(inp, ourlang.VariableReference):
-        wgn.add_statement('local.get', '${}'.format(inp.name))
-        return
+        if isinstance(inp.variable, ourlang.FunctionParam):
+            wgn.add_statement('local.get', '${}'.format(inp.variable.name))
+            return
+
+        if isinstance(inp.variable, ourlang.ModuleConstantDef):
+            assert isinstance(inp.type3, type3types.Type3), type3types.TYPE3_ASSERTION_ERROR
+
+            if isinstance(inp.type3, type3types.StructType3):
+                assert inp.variable.data_block is not None, 'Structs must be memory stored'
+                assert inp.variable.data_block.address is not None, 'Value not allocated'
+                wgn.i32.const(inp.variable.data_block.address)
+                return
+
+            if isinstance(inp.type3, type3types.AppliedType3):
+                if inp.type3.base == type3types.static_array:
+                    assert inp.variable.data_block is not None, 'Static arrays must be memory stored'
+                    assert inp.variable.data_block.address is not None, 'Value not allocated'
+                    wgn.i32.const(inp.variable.data_block.address)
+                    return
+
+                if inp.type3.base == type3types.tuple:
+                    assert inp.variable.data_block is not None, 'Tuples must be memory stored'
+                    assert inp.variable.data_block.address is not None, 'Value not allocated'
+                    wgn.i32.const(inp.variable.data_block.address)
+                    return
+
+                raise NotImplementedError(expression, inp.variable, inp.type3.base)
+
+            assert inp.variable.data_block is None, 'Primitives are not memory stored'
+
+            expression(wgn, inp.variable.constant)
+            return
+
+        raise NotImplementedError(expression, inp.variable)
 
     if isinstance(inp, ourlang.BinaryOp):
         expression(wgn, inp.left)
         expression(wgn, inp.right)
 
-        if isinstance(inp.type, typing.TypeUInt8):
+        assert isinstance(inp.type3, type3types.Type3), type3types.TYPE3_ASSERTION_ERROR
+        # FIXME: Re-implement build-in operators
+        # Maybe operator_annotation is the way to go
+        # Maybe the older stuff below that is the way to go
+
+        operator_annotation = f'({inp.operator}) :: {inp.left.type3:s} -> {inp.right.type3:s} -> {inp.type3:s}'
+        if operator_annotation == '(>) :: i32 -> i32 -> bool':
+            wgn.add_statement('i32.gt_s')
+            return
+
+        if operator_annotation == '(<) :: u64 -> u64 -> bool':
+            wgn.add_statement('i64.lt_u')
+            return
+        if operator_annotation == '(==) :: u64 -> u64 -> bool':
+            wgn.add_statement('i64.eq')
+            return
+
+        if inp.type3 == type3types.u8:
             if operator := U8_OPERATOR_MAP.get(inp.operator, None):
                 wgn.add_statement(f'i32.{operator}')
                 return
-        if isinstance(inp.type, typing.TypeUInt32):
+        if inp.type3 == type3types.u32:
             if operator := OPERATOR_MAP.get(inp.operator, None):
                 wgn.add_statement(f'i32.{operator}')
                 return
             if operator := U32_OPERATOR_MAP.get(inp.operator, None):
                 wgn.add_statement(f'i32.{operator}')
                 return
-        if isinstance(inp.type, typing.TypeUInt64):
+        if inp.type3 == type3types.u64:
             if operator := OPERATOR_MAP.get(inp.operator, None):
                 wgn.add_statement(f'i64.{operator}')
                 return
             if operator := U64_OPERATOR_MAP.get(inp.operator, None):
                 wgn.add_statement(f'i64.{operator}')
                 return
-        if isinstance(inp.type, typing.TypeInt32):
+        if inp.type3 == type3types.i32:
             if operator := OPERATOR_MAP.get(inp.operator, None):
                 wgn.add_statement(f'i32.{operator}')
                 return
             if operator := I32_OPERATOR_MAP.get(inp.operator, None):
                 wgn.add_statement(f'i32.{operator}')
                 return
-        if isinstance(inp.type, typing.TypeInt64):
+        if inp.type3 == type3types.i64:
             if operator := OPERATOR_MAP.get(inp.operator, None):
                 wgn.add_statement(f'i64.{operator}')
                 return
             if operator := I64_OPERATOR_MAP.get(inp.operator, None):
                 wgn.add_statement(f'i64.{operator}')
                 return
-        if isinstance(inp.type, typing.TypeFloat32):
+        if inp.type3 == type3types.f32:
             if operator := OPERATOR_MAP.get(inp.operator, None):
                 wgn.add_statement(f'f32.{operator}')
                 return
-        if isinstance(inp.type, typing.TypeFloat64):
+            if operator := F32_OPERATOR_MAP.get(inp.operator, None):
+                wgn.add_statement(f'f32.{operator}')
+                return
+        if inp.type3 == type3types.f64:
             if operator := OPERATOR_MAP.get(inp.operator, None):
                 wgn.add_statement(f'f64.{operator}')
                 return
+            if operator := F64_OPERATOR_MAP.get(inp.operator, None):
+                wgn.add_statement(f'f64.{operator}')
+                return
 
-        raise NotImplementedError(expression, inp.type, inp.operator)
+        raise NotImplementedError(expression, inp.operator, inp.left.type3, inp.right.type3, inp.type3)
 
     if isinstance(inp, ourlang.UnaryOp):
         expression(wgn, inp.right)
 
-        if isinstance(inp.type, typing.TypeFloat32):
-            if inp.operator in ourlang.WEBASSEMBLY_BUILDIN_FLOAT_OPS:
+        assert isinstance(inp.type3, type3types.Type3), type3types.TYPE3_ASSERTION_ERROR
+
+        if inp.type3 == type3types.f32:
+            if inp.operator in ourlang.WEBASSEMBLY_BUILTIN_FLOAT_OPS:
                 wgn.add_statement(f'f32.{inp.operator}')
                 return
-        if isinstance(inp.type, typing.TypeFloat64):
-            if inp.operator in ourlang.WEBASSEMBLY_BUILDIN_FLOAT_OPS:
+        if inp.type3 == type3types.f64:
+            if inp.operator in ourlang.WEBASSEMBLY_BUILTIN_FLOAT_OPS:
                 wgn.add_statement(f'f64.{inp.operator}')
                 return
 
-        if isinstance(inp.type, typing.TypeInt32):
+        if inp.type3 == type3types.u32:
             if inp.operator == 'len':
-                if isinstance(inp.right.type, typing.TypeBytes):
+                if inp.right.type3 == type3types.bytes:
                     wgn.i32.load()
                     return
 
         if inp.operator == 'cast':
-            if isinstance(inp.type, typing.TypeUInt32) and isinstance(inp.right.type, typing.TypeUInt8):
+            if inp.type3 == type3types.u32 and inp.right.type3 == type3types.u8:
                 # Nothing to do, you can use an u8 value as a u32 no problem
                 return
 
-        raise NotImplementedError(expression, inp.type, inp.operator)
+        raise NotImplementedError(expression, inp.type3, inp.operator)
 
     if isinstance(inp, ourlang.FunctionCall):
         for arg in inp.arguments:
@@ -242,104 +371,103 @@ def expression(wgn: WasmGenerator, inp: ourlang.Expression) -> None:
         wgn.add_statement('call', '${}'.format(inp.function.name))
         return
 
-    if isinstance(inp, ourlang.AccessBytesIndex):
-        if not isinstance(inp.type, typing.TypeUInt8):
-            raise NotImplementedError(inp, inp.type)
-
-        expression(wgn, inp.varref)
-        expression(wgn, inp.index)
-        wgn.call(stdlib_types.__subscript_bytes__)
+    if isinstance(inp, ourlang.TupleInstantiation):
+        tuple_instantiation(wgn, inp)
         return
 
-    if isinstance(inp, ourlang.AccessStructMember):
-        mtyp = LOAD_STORE_TYPE_MAP.get(inp.member.type.__class__)
-        if mtyp is None:
-            # In the future might extend this by having structs or tuples
-            # as members of struct or tuples
-            raise NotImplementedError(expression, inp, inp.member)
+    if isinstance(inp, ourlang.Subscript):
+        assert isinstance(inp.varref.type3, type3types.Type3), type3types.TYPE3_ASSERTION_ERROR
 
-        expression(wgn, inp.varref)
-        wgn.add_statement(f'{mtyp}.load', 'offset=' + str(inp.member.offset))
-        return
-
-    if isinstance(inp, ourlang.AccessTupleMember):
-        mtyp = LOAD_STORE_TYPE_MAP.get(inp.member.type.__class__)
-        if mtyp is None:
-            # In the future might extend this by having structs or tuples
-            # as members of struct or tuples
-            raise NotImplementedError(expression, inp, inp.member)
-
-        expression(wgn, inp.varref)
-        wgn.add_statement(f'{mtyp}.load', 'offset=' + str(inp.member.offset))
-        return
-
-    if isinstance(inp, ourlang.AccessStaticArrayMember):
-        mtyp = LOAD_STORE_TYPE_MAP.get(inp.static_array.member_type.__class__)
-        if mtyp is None:
-            # In the future might extend this by having structs or tuples
-            # as members of static arrays
-            raise NotImplementedError(expression, inp, inp.member)
-
-        if isinstance(inp.member, typing.TypeStaticArrayMember):
+        if inp.varref.type3 is type3types.bytes:
             expression(wgn, inp.varref)
-            wgn.add_statement(f'{mtyp}.load', 'offset=' + str(inp.member.offset))
+            expression(wgn, inp.index)
+            wgn.call(stdlib_types.__subscript_bytes__)
             return
 
+        if isinstance(inp.varref.type3, type3types.AppliedType3):
+            if inp.varref.type3.base == type3types.static_array:
+                assert 2 == len(inp.varref.type3.args)
+                el_type = inp.varref.type3.args[0]
+                assert isinstance(el_type, type3types.Type3)
+                el_len = inp.varref.type3.args[1]
+                assert isinstance(el_len, type3types.IntType3)
+
+                # OPTIMIZE: If index is a constant, we can use offset instead of multiply
+                # and we don't need to do the out of bounds check
+
+                expression(wgn, inp.varref)
+
+                tmp_var = wgn.temp_var_i32('index')
+                expression(wgn, inp.index)
+                wgn.local.tee(tmp_var)
+
+                # Out of bounds check based on el_len.value
+                wgn.i32.const(el_len.value)
+                wgn.i32.ge_u()
+                with wgn.if_():
+                    wgn.unreachable(comment='Out of bounds')
+
+                wgn.local.get(tmp_var)
+                wgn.i32.const(_calculate_alloc_size(el_type))
+                wgn.i32.mul()
+                wgn.i32.add()
+
+                assert isinstance(el_type, type3types.PrimitiveType3), NotImplementedError('Tuple of applied types / structs')
+                mtyp = LOAD_STORE_TYPE_MAP[el_type.name]
+
+                wgn.add_statement(f'{mtyp}.load')
+                return
+
+            if inp.varref.type3.base == type3types.tuple:
+                assert isinstance(inp.index, ourlang.ConstantPrimitive)
+                assert isinstance(inp.index.value, int)
+
+                offset = 0
+                for el_type in inp.varref.type3.args[0:inp.index.value]:
+                    assert isinstance(el_type, type3types.Type3), type3types.TYPE3_ASSERTION_ERROR
+                    offset += _calculate_alloc_size(el_type)
+
+                # This doubles as the out of bounds check
+                el_type = inp.varref.type3.args[inp.index.value]
+                assert isinstance(el_type, type3types.Type3), type3types.TYPE3_ASSERTION_ERROR
+
+                expression(wgn, inp.varref)
+
+                assert isinstance(el_type, type3types.PrimitiveType3), NotImplementedError('Tuple of applied types / structs')
+                mtyp = LOAD_STORE_TYPE_MAP[el_type.name]
+
+                wgn.add_statement(f'{mtyp}.load', f'offset={offset}')
+                return
+
+        raise NotImplementedError(expression, inp, inp.varref.type3)
+
+    if isinstance(inp, ourlang.AccessStructMember):
+        assert isinstance(inp.struct_type3.members[inp.member], type3types.PrimitiveType3), NotImplementedError('Tuple of applied types / structs')
+        mtyp = LOAD_STORE_TYPE_MAP[inp.struct_type3.members[inp.member].name]
+
         expression(wgn, inp.varref)
-        expression(wgn, inp.member)
-        wgn.i32.const(inp.static_array.member_type.alloc_size())
-        wgn.i32.mul()
-        wgn.i32.add()
-        wgn.add_statement(f'{mtyp}.load')
+        wgn.add_statement(f'{mtyp}.load', 'offset=' + str(_calculate_member_offset(
+            inp.struct_type3, inp.member
+        )))
         return
 
     if isinstance(inp, ourlang.Fold):
         expression_fold(wgn, inp)
         return
 
-    if isinstance(inp, ourlang.ModuleConstantReference):
-        if isinstance(inp.type, typing.TypeTuple):
-            assert isinstance(inp.definition.constant, ourlang.ConstantTuple)
-            assert inp.definition.data_block is not None, 'Combined values are memory stored'
-            assert inp.definition.data_block.address is not None, 'Value not allocated'
-            wgn.i32.const(inp.definition.data_block.address)
-            return
-
-        if isinstance(inp.type, typing.TypeStaticArray):
-            assert isinstance(inp.definition.constant, ourlang.ConstantStaticArray)
-            assert inp.definition.data_block is not None, 'Combined values are memory stored'
-            assert inp.definition.data_block.address is not None, 'Value not allocated'
-            wgn.i32.const(inp.definition.data_block.address)
-            return
-
-        assert inp.definition.data_block is None, 'Primitives are not memory stored'
-
-        mtyp = LOAD_STORE_TYPE_MAP.get(inp.type.__class__)
-        if mtyp is None:
-            # In the future might extend this by having structs or tuples
-            # as members of struct or tuples
-            raise NotImplementedError(expression, inp, inp.type)
-
-        expression(wgn, inp.definition.constant)
-        return
-
     raise NotImplementedError(expression, inp)
 
 def expression_fold(wgn: WasmGenerator, inp: ourlang.Fold) -> None:
     """
     Compile: Fold expression
     """
-    mtyp = LOAD_STORE_TYPE_MAP.get(inp.base.type.__class__)
-    if mtyp is None:
-        # In the future might extend this by having structs or tuples
-        # as members of struct or tuples
-        raise NotImplementedError(expression, inp, inp.base)
+    assert isinstance(inp.type3, type3types.Type3), type3types.TYPE3_ASSERTION_ERROR
 
-    if inp.iter.type.__class__.__name__ != 'TypeBytes':
-        raise NotImplementedError(expression, inp, inp.iter.type)
+    if inp.iter.type3 is not type3types.bytes:
+        raise NotImplementedError(expression_fold, inp, inp.iter.type3)
 
     wgn.add_statement('nop', comment='acu :: u8')
-    acu_var = wgn.temp_var_u8(f'fold_{codestyle.type_(inp.type)}_acu')
+    acu_var = wgn.temp_var_u8(f'fold_{codestyle.type3(inp.type3)}_acu')
     wgn.add_statement('nop', comment='adr :: bytes*')
     adr_var = wgn.temp_var_i32('fold_i32_adr')
     wgn.add_statement('nop', comment='len :: i32')
@@ -359,7 +487,7 @@ def expression_fold(wgn: WasmGenerator, inp: ourlang.Fold) -> None:
     wgn.local.set(len_var)
 
     wgn.add_statement('nop', comment='i = 0')
-    idx_var = wgn.temp_var_i32(f'fold_{codestyle.type_(inp.type)}_idx')
+    idx_var = wgn.temp_var_i32(f'fold_{codestyle.type3(inp.type3)}_idx')
     wgn.i32.const(0)
     wgn.local.set(idx_var)
 
@@ -450,7 +578,7 @@ def function_argument(inp: ourlang.FunctionParam) -> wasm.Param:
     """
     Compile: function argument
     """
-    return (inp[0], type_(inp[1]), )
+    return (inp.name, type3(inp.type3), )
 
 def import_(inp: ourlang.Function) -> wasm.Import:
     """
@@ -466,7 +594,7 @@ def import_(inp: ourlang.Function) -> wasm.Import:
             function_argument(x)
             for x in inp.posonlyargs
         ],
-        type_(inp.returns)
+        type3(inp.returns_type3)
     )
 
 def function(inp: ourlang.Function) -> wasm.Function:
@@ -477,9 +605,7 @@ def function(inp: ourlang.Function) -> wasm.Function:
 
     wgn = WasmGenerator()
 
-    if isinstance(inp, ourlang.TupleConstructor):
-        _generate_tuple_constructor(wgn, inp)
-    elif isinstance(inp, ourlang.StructConstructor):
+    if isinstance(inp, ourlang.StructConstructor):
         _generate_struct_constructor(wgn, inp)
     else:
         for stat in inp.statements:
@@ -496,7 +622,7 @@ def function(inp: ourlang.Function) -> wasm.Function:
             (k, v.wasm_type(), )
             for k, v in wgn.locals.items()
         ],
-        type_(inp.returns),
+        type3(inp.returns_type3),
         wgn.statements
     )
 
@@ -555,38 +681,47 @@ def module_data(inp: ourlang.ModuleData) -> bytes:
     for block in inp.blocks:
         block.address = unalloc_ptr + 4 # 4 bytes for allocator header
 
-        data_list = []
+        data_list: List[bytes] = []
 
         for constant in block.data:
-            if isinstance(constant, ourlang.ConstantUInt8):
+            assert isinstance(constant.type3, type3types.Type3), (id(constant), type3types.TYPE3_ASSERTION_ERROR)
+
+            if constant.type3 == type3types.u8:
+                assert isinstance(constant.value, int)
                 data_list.append(module_data_u8(constant.value))
                 continue
 
-            if isinstance(constant, ourlang.ConstantUInt32):
+            if constant.type3 == type3types.u32:
+                assert isinstance(constant.value, int)
                 data_list.append(module_data_u32(constant.value))
                 continue
 
-            if isinstance(constant, ourlang.ConstantUInt64):
+            if constant.type3 == type3types.u64:
+                assert isinstance(constant.value, int)
                 data_list.append(module_data_u64(constant.value))
                 continue
 
-            if isinstance(constant, ourlang.ConstantInt32):
+            if constant.type3 == type3types.i32:
+                assert isinstance(constant.value, int)
                 data_list.append(module_data_i32(constant.value))
                 continue
 
-            if isinstance(constant, ourlang.ConstantInt64):
+            if constant.type3 == type3types.i64:
+                assert isinstance(constant.value, int)
                 data_list.append(module_data_i64(constant.value))
                 continue
 
-            if isinstance(constant, ourlang.ConstantFloat32):
+            if constant.type3 == type3types.f32:
+                assert isinstance(constant.value, float)
                 data_list.append(module_data_f32(constant.value))
                 continue
 
-            if isinstance(constant, ourlang.ConstantFloat64):
+            if constant.type3 == type3types.f64:
+                assert isinstance(constant.value, float)
                 data_list.append(module_data_f64(constant.value))
                 continue
 
-            raise NotImplementedError(constant)
+            raise NotImplementedError(constant, constant.type3, constant.value)
 
         block_data = b''.join(data_list)
 
@@ -636,48 +771,70 @@ def module(inp: ourlang.Module) -> wasm.Module:
 
     return result
 
-def _generate_tuple_constructor(wgn: WasmGenerator, inp: ourlang.TupleConstructor) -> None:
-    tmp_var = wgn.temp_var_i32('tuple_adr')
-
-    # Allocated the required amounts of bytes in memory
-    wgn.i32.const(inp.tuple.alloc_size())
-    wgn.call(stdlib_alloc.__alloc__)
-    wgn.local.set(tmp_var)
-
-    # Store each member individually
-    for member in inp.tuple.members:
-        mtyp = LOAD_STORE_TYPE_MAP.get(member.type.__class__)
-        if mtyp is None:
-            # In the future might extend this by having structs or tuples
-            # as members of struct or tuples
-            raise NotImplementedError(expression, inp, member)
-
-        wgn.local.get(tmp_var)
-        wgn.add_statement('local.get', f'$arg{member.idx}')
-        wgn.add_statement(f'{mtyp}.store', 'offset=' + str(member.offset))
-
-    # Return the allocated address
-    wgn.local.get(tmp_var)
-
 def _generate_struct_constructor(wgn: WasmGenerator, inp: ourlang.StructConstructor) -> None:
     tmp_var = wgn.temp_var_i32('struct_adr')
 
     # Allocated the required amounts of bytes in memory
-    wgn.i32.const(inp.struct.alloc_size())
+    wgn.i32.const(_calculate_alloc_size(inp.struct_type3))
     wgn.call(stdlib_alloc.__alloc__)
     wgn.local.set(tmp_var)
 
     # Store each member individually
-    for member in inp.struct.members:
-        mtyp = LOAD_STORE_TYPE_MAP.get(member.type.__class__)
+    for memname, mtyp3 in inp.struct_type3.members.items():
+        mtyp = LOAD_STORE_TYPE_MAP.get(mtyp3.name)
         if mtyp is None:
             # In the future might extend this by having structs or tuples
             # as members of struct or tuples
-            raise NotImplementedError(expression, inp, member)
+            raise NotImplementedError(expression, inp, mtyp3)
 
         wgn.local.get(tmp_var)
-        wgn.add_statement('local.get', f'${member.name}')
-        wgn.add_statement(f'{mtyp}.store', 'offset=' + str(member.offset))
+        wgn.add_statement('local.get', f'${memname}')
+        wgn.add_statement(f'{mtyp}.store', 'offset=' + str(_calculate_member_offset(
+            inp.struct_type3, memname
+        )))
 
     # Return the allocated address
     wgn.local.get(tmp_var)
+
+def _calculate_alloc_size(typ: Union[type3types.StructType3, type3types.Type3]) -> int:
+    if typ == type3types.u8:
+        return 4 # FIXME: We allocate 4 bytes for every u8 since you load them into an i32
+
+    if typ in (type3types.u32, type3types.i32, type3types.f32, ):
+        return 4
+
+    if typ in (type3types.u64, type3types.i64, type3types.f64, ):
+        return 8
+
+    if isinstance(typ, type3types.StructType3):
+        return sum(
+            _calculate_alloc_size(x)
+            for x in typ.members.values()
+        )
+
+    if isinstance(typ, type3types.AppliedType3):
+        if typ.base is type3types.tuple:
+            size = 0
+            for arg in typ.args:
+                assert not isinstance(arg, type3types.IntType3)
+
+                if isinstance(arg, type3types.PlaceholderForType):
+                    assert not arg.resolve_as is None
+                    arg = arg.resolve_as
+
+                size += _calculate_alloc_size(arg)
+
+            return size
+
+    raise NotImplementedError(_calculate_alloc_size, typ)
+
+def _calculate_member_offset(struct_type3: type3types.StructType3, member: str) -> int:
+    result = 0
+
+    for mem, memtyp in struct_type3.members.items():
+        if member == mem:
+            return result
+
+        result += _calculate_alloc_size(memtyp)
+
+    raise Exception(f'{member} not in {struct_type3}')
diff --git a/phasm/ourlang.py b/phasm/ourlang.py
index 5f19d2e..01430b9 100644
--- a/phasm/ourlang.py
+++ b/phasm/ourlang.py
@@ -1,128 +1,51 @@
 """
 Contains the syntax tree for ourlang
 """
-from typing import Dict, List, Tuple, Optional, Union
+from typing import Dict, List, Optional, Union
 
 import enum
 
 from typing_extensions import Final
 
-WEBASSEMBLY_BUILDIN_FLOAT_OPS: Final = ('abs', 'sqrt', 'ceil', 'floor', 'trunc', 'nearest', )
-WEBASSEMBLY_BUILDIN_BYTES_OPS: Final = ('len', )
+WEBASSEMBLY_BUILTIN_FLOAT_OPS: Final = ('abs', 'sqrt', 'ceil', 'floor', 'trunc', 'nearest', )
+WEBASSEMBLY_BUILTIN_BYTES_OPS: Final = ('len', )
 
-from .typing import (
-    TypeBase,
-    TypeNone,
-    TypeBool,
-    TypeUInt8, TypeUInt32, TypeUInt64,
-    TypeInt32, TypeInt64,
-    TypeFloat32, TypeFloat64,
-    TypeBytes,
-    TypeTuple, TypeTupleMember,
-    TypeStaticArray, TypeStaticArrayMember,
-    TypeStruct, TypeStructMember,
-)
+from .type3 import types as type3types
+from .type3.types import Type3, Type3OrPlaceholder, PlaceholderForType, StructType3
 
 class Expression:
     """
     An expression within a statement
     """
-    __slots__ = ('type', )
+    __slots__ = ('type3', )
 
-    type: TypeBase
+    type3: Type3OrPlaceholder
 
-    def __init__(self, type_: TypeBase) -> None:
-        self.type = type_
+    def __init__(self) -> None:
+        self.type3 = PlaceholderForType([self])
 
 class Constant(Expression):
     """
     An constant value expression within a statement
+
+    # FIXME: Rename to literal
     """
     __slots__ = ()
 
-class ConstantUInt8(Constant):
+class ConstantPrimitive(Constant):
     """
-    An UInt8 constant value expression within a statement
+    An primitive constant value expression within a statement
     """
     __slots__ = ('value', )
 
-    value: int
+    value: Union[int, float]
 
-    def __init__(self, type_: TypeUInt8, value: int) -> None:
-        super().__init__(type_)
+    def __init__(self, value: Union[int, float]) -> None:
+        super().__init__()
         self.value = value
 
-class ConstantUInt32(Constant):
-    """
-    An UInt32 constant value expression within a statement
-    """
-    __slots__ = ('value', )
-
-    value: int
-
-    def __init__(self, type_: TypeUInt32, value: int) -> None:
-        super().__init__(type_)
-        self.value = value
-
-class ConstantUInt64(Constant):
-    """
-    An UInt64 constant value expression within a statement
-    """
-    __slots__ = ('value', )
-
-    value: int
-
-    def __init__(self, type_: TypeUInt64, value: int) -> None:
-        super().__init__(type_)
-        self.value = value
-
-class ConstantInt32(Constant):
-    """
-    An Int32 constant value expression within a statement
-    """
-    __slots__ = ('value', )
-
-    value: int
-
-    def __init__(self, type_: TypeInt32, value: int) -> None:
-        super().__init__(type_)
-        self.value = value
-
-class ConstantInt64(Constant):
-    """
-    An Int64 constant value expression within a statement
-    """
-    __slots__ = ('value', )
-
-    value: int
-
-    def __init__(self, type_: TypeInt64, value: int) -> None:
-        super().__init__(type_)
-        self.value = value
-
-class ConstantFloat32(Constant):
-    """
-    An Float32 constant value expression within a statement
-    """
-    __slots__ = ('value', )
-
-    value: float
-
-    def __init__(self, type_: TypeFloat32, value: float) -> None:
-        super().__init__(type_)
-        self.value = value
-
-class ConstantFloat64(Constant):
-    """
-    An Float64 constant value expression within a statement
-    """
-    __slots__ = ('value', )
-
-    value: float
-
-    def __init__(self, type_: TypeFloat64, value: float) -> None:
-        super().__init__(type_)
-        self.value = value
+    def __repr__(self) -> str:
+        return f'ConstantPrimitive({repr(self.value)})'
 
 class ConstantTuple(Constant):
     """
@@ -130,35 +53,43 @@ class ConstantTuple(Constant):
     """
     __slots__ = ('value', )
 
-    value: List[Constant]
+    value: List[ConstantPrimitive]
 
-    def __init__(self, type_: TypeTuple, value: List[Constant]) -> None:
-        super().__init__(type_)
+    def __init__(self, value: List[ConstantPrimitive]) -> None: # FIXME: Tuple of tuples?
+        super().__init__()
         self.value = value
 
-class ConstantStaticArray(Constant):
-    """
-    A StaticArray constant value expression within a statement
-    """
-    __slots__ = ('value', )
+    def __repr__(self) -> str:
+        return f'ConstantTuple({repr(self.value)})'
 
-    value: List[Constant]
+class ConstantStruct(Constant):
+    """
+    A Struct constant value expression within a statement
+    """
+    __slots__ = ('struct_name', 'value', )
 
-    def __init__(self, type_: TypeStaticArray, value: List[Constant]) -> None:
-        super().__init__(type_)
+    struct_name: str
+    value: List[ConstantPrimitive]
+
+    def __init__(self, struct_name: str, value: List[ConstantPrimitive]) -> None: # FIXME: Struct of structs?
+        super().__init__()
+        self.struct_name = struct_name
         self.value = value
 
+    def __repr__(self) -> str:
+        return f'ConstantStruct({repr(self.struct_name)}, {repr(self.value)})'
+
 class VariableReference(Expression):
     """
     An variable reference expression within a statement
     """
-    __slots__ = ('name', )
+    __slots__ = ('variable', )
 
-    name: str
+    variable: Union['ModuleConstantDef', 'FunctionParam'] # also possibly local
 
-    def __init__(self, type_: TypeBase, name: str) -> None:
-        super().__init__(type_)
-        self.name = name
+    def __init__(self, variable: Union['ModuleConstantDef', 'FunctionParam']) -> None:
+        super().__init__()
+        self.variable = variable
 
 class UnaryOp(Expression):
     """
@@ -169,8 +100,8 @@ class UnaryOp(Expression):
     operator: str
     right: Expression
 
-    def __init__(self, type_: TypeBase, operator: str, right: Expression) -> None:
-        super().__init__(type_)
+    def __init__(self, operator: str, right: Expression) -> None:
+        super().__init__()
 
         self.operator = operator
         self.right = right
@@ -185,13 +116,16 @@ class BinaryOp(Expression):
     left: Expression
     right: Expression
 
-    def __init__(self, type_: TypeBase, operator: str, left: Expression, right: Expression) -> None:
-        super().__init__(type_)
+    def __init__(self, operator: str, left: Expression, right: Expression) -> None:
+        super().__init__()
 
         self.operator = operator
         self.left = left
         self.right = right
 
+    def __repr__(self) -> str:
+        return f'BinaryOp({repr(self.operator)}, {repr(self.left)}, {repr(self.right)})'
+
 class FunctionCall(Expression):
     """
     A function call expression within a statement
@@ -202,22 +136,36 @@ class FunctionCall(Expression):
     arguments: List[Expression]
 
     def __init__(self, function: 'Function') -> None:
-        super().__init__(function.returns)
+        super().__init__()
 
         self.function = function
         self.arguments = []
 
-class AccessBytesIndex(Expression):
+class TupleInstantiation(Expression):
     """
-    Access a bytes index for reading
+    Instantiation a tuple
+    """
+    __slots__ = ('elements', )
+
+    elements: List[Expression]
+
+    def __init__(self, elements: List[Expression]) -> None:
+        super().__init__()
+
+        self.elements = elements
+
+class Subscript(Expression):
+    """
+    A subscript, for example to refer to a static array or tuple
+    by index
     """
     __slots__ = ('varref', 'index', )
 
     varref: VariableReference
     index: Expression
 
-    def __init__(self, type_: TypeBase, varref: VariableReference, index: Expression) -> None:
-        super().__init__(type_)
+    def __init__(self, varref: VariableReference, index: Expression) -> None:
+        super().__init__()
 
         self.varref = varref
         self.index = index
@@ -226,47 +174,17 @@ class AccessStructMember(Expression):
     """
     Access a struct member for reading of writing
     """
-    __slots__ = ('varref', 'member', )
+    __slots__ = ('varref', 'struct_type3', 'member', )
 
     varref: VariableReference
-    member: TypeStructMember
+    struct_type3: StructType3
+    member: str
 
-    def __init__(self, varref: VariableReference,  member: TypeStructMember) -> None:
-        super().__init__(member.type)
+    def __init__(self, varref: VariableReference,  struct_type3: StructType3, member: str) -> None:
+        super().__init__()
 
         self.varref = varref
-        self.member = member
-
-class AccessTupleMember(Expression):
-    """
-    Access a tuple member for reading of writing
-    """
-    __slots__ = ('varref', 'member', )
-
-    varref: VariableReference
-    member: TypeTupleMember
-
-    def __init__(self, varref: VariableReference, member: TypeTupleMember, ) -> None:
-        super().__init__(member.type)
-
-        self.varref = varref
-        self.member = member
-
-class AccessStaticArrayMember(Expression):
-    """
-    Access a tuple member for reading of writing
-    """
-    __slots__ = ('varref', 'static_array', 'member', )
-
-    varref: Union['ModuleConstantReference', VariableReference]
-    static_array: TypeStaticArray
-    member: Union[Expression, TypeStaticArrayMember]
-
-    def __init__(self, varref: Union['ModuleConstantReference', VariableReference], static_array: TypeStaticArray, member: Union[TypeStaticArrayMember, Expression], ) -> None:
-        super().__init__(static_array.member_type)
-
-        self.varref = varref
-        self.static_array = static_array
+        self.struct_type3 = struct_type3
         self.member = member
 
 class Fold(Expression):
@@ -287,31 +205,18 @@ class Fold(Expression):
 
     def __init__(
             self,
-            type_: TypeBase,
             dir_: Direction,
             func: 'Function',
             base: Expression,
             iter_: Expression,
         ) -> None:
-        super().__init__(type_)
+        super().__init__()
 
         self.dir = dir_
         self.func = func
         self.base = base
         self.iter = iter_
 
-class ModuleConstantReference(Expression):
-    """
-    An reference to a module constant expression within a statement
-    """
-    __slots__ = ('definition', )
-
-    definition: 'ModuleConstantDef'
-
-    def __init__(self, type_: TypeBase, definition: 'ModuleConstantDef') -> None:
-        super().__init__(type_)
-        self.definition = definition
-
 class Statement:
     """
     A statement within a function
@@ -348,20 +253,31 @@ class StatementIf(Statement):
         self.statements = []
         self.else_statements = []
 
-FunctionParam = Tuple[str, TypeBase]
+class FunctionParam:
+    """
+    A parameter for a Function
+    """
+    __slots__ = ('name', 'type3', )
+
+    name: str
+    type3: Type3OrPlaceholder
+
+    def __init__(self, name: str, type3: Optional[Type3]) -> None:
+        self.name = name
+        self.type3 = PlaceholderForType([self]) if type3 is None else type3
 
 class Function:
     """
     A function processes input and produces output
     """
-    __slots__ = ('name', 'lineno', 'exported', 'imported', 'statements', 'returns', 'posonlyargs', )
+    __slots__ = ('name', 'lineno', 'exported', 'imported', 'statements', 'returns_type3', 'posonlyargs', )
 
     name: str
     lineno: int
     exported: bool
     imported: bool
     statements: List[Statement]
-    returns: TypeBase
+    returns_type3: Type3
     posonlyargs: List[FunctionParam]
 
     def __init__(self, name: str, lineno: int) -> None:
@@ -370,9 +286,22 @@ class Function:
         self.exported = False
         self.imported = False
         self.statements = []
-        self.returns = TypeNone()
+        self.returns_type3 = type3types.none # FIXME: This could be a placeholder
         self.posonlyargs = []
 
+class StructDefinition:
+    """
+    The definition for a struct
+    """
+    __slots__ = ('struct_type3', 'lineno', )
+
+    struct_type3: StructType3
+    lineno: int
+
+    def __init__(self, struct_type3: StructType3, lineno: int) -> None:
+        self.struct_type3 = struct_type3
+        self.lineno = lineno
+
 class StructConstructor(Function):
     """
     The constructor method for a struct
@@ -380,56 +309,36 @@ class StructConstructor(Function):
     A function will generated to instantiate a struct. The arguments
     will be the defaults
     """
-    __slots__ = ('struct', )
+    __slots__ = ('struct_type3', )
 
-    struct: TypeStruct
+    struct_type3: StructType3
 
-    def __init__(self, struct: TypeStruct) -> None:
-        super().__init__(f'@{struct.name}@__init___@', -1)
+    def __init__(self, struct_type3: StructType3) -> None:
+        super().__init__(f'@{struct_type3.name}@__init___@', -1)
 
-        self.returns = struct
+        self.returns_type3 = struct_type3
 
-        for mem in struct.members:
-            self.posonlyargs.append((mem.name, mem.type, ))
+        for mem, typ in struct_type3.members.items():
+            self.posonlyargs.append(FunctionParam(mem, typ, ))
 
-        self.struct = struct
-
-class TupleConstructor(Function):
-    """
-    The constructor method for a tuple
-    """
-    __slots__ = ('tuple', )
-
-    tuple: TypeTuple
-
-    def __init__(self, tuple_: TypeTuple) -> None:
-        name = tuple_.render_internal_name()
-
-        super().__init__(f'@{name}@__init___@', -1)
-
-        self.returns = tuple_
-
-        for mem in tuple_.members:
-            self.posonlyargs.append((f'arg{mem.idx}', mem.type, ))
-
-        self.tuple = tuple_
+        self.struct_type3 = struct_type3
 
 class ModuleConstantDef:
     """
     A constant definition within a module
     """
-    __slots__ = ('name', 'lineno', 'type', 'constant', 'data_block', )
+    __slots__ = ('name', 'lineno', 'type3', 'constant', 'data_block', )
 
     name: str
     lineno: int
-    type: TypeBase
+    type3: Type3
     constant: Constant
     data_block: Optional['ModuleDataBlock']
 
-    def __init__(self, name: str, lineno: int, type_: TypeBase, constant: Constant, data_block: Optional['ModuleDataBlock']) -> None:
+    def __init__(self, name: str, lineno: int, type3: Type3, constant: Constant, data_block: Optional['ModuleDataBlock']) -> None:
         self.name = name
         self.lineno = lineno
-        self.type = type_
+        self.type3 = type3
         self.constant = constant
         self.data_block = data_block
 
@@ -439,10 +348,10 @@ class ModuleDataBlock:
     """
     __slots__ = ('data', 'address', )
 
-    data: List[Constant]
+    data: List[ConstantPrimitive]
     address: Optional[int]
 
-    def __init__(self, data: List[Constant]) -> None:
+    def __init__(self, data: List[ConstantPrimitive]) -> None:
         self.data = data
         self.address = None
 
@@ -461,27 +370,15 @@ class Module:
     """
     A module is a file and consists of functions
     """
-    __slots__ = ('data', 'types',  'structs', 'constant_defs', 'functions',)
+    __slots__ = ('data', 'types',  'struct_definitions', 'constant_defs', 'functions',)
 
     data: ModuleData
-    types: Dict[str, TypeBase]
-    structs: Dict[str, TypeStruct]
+    struct_definitions: Dict[str, StructDefinition]
     constant_defs: Dict[str, ModuleConstantDef]
     functions: Dict[str, Function]
 
     def __init__(self) -> None:
-        self.types = {
-            'None': TypeNone(),
-            'u8': TypeUInt8(),
-            'u32': TypeUInt32(),
-            'u64': TypeUInt64(),
-            'i32': TypeInt32(),
-            'i64': TypeInt64(),
-            'f32': TypeFloat32(),
-            'f64': TypeFloat64(),
-            'bytes': TypeBytes(),
-        }
         self.data = ModuleData()
-        self.structs = {}
+        self.struct_definitions = {}
         self.constant_defs = {}
         self.functions = {}
diff --git a/phasm/parser.py b/phasm/parser.py
index d95bfce..5ee9d56 100644
--- a/phasm/parser.py
+++ b/phasm/parser.py
@@ -5,49 +5,30 @@ from typing import Any, Dict, NoReturn, Union
 
 import ast
 
-from .typing import (
-    TypeBase,
-    TypeUInt8,
-    TypeUInt32,
-    TypeUInt64,
-    TypeInt32,
-    TypeInt64,
-    TypeFloat32,
-    TypeFloat64,
-    TypeBytes,
-    TypeStruct,
-    TypeStructMember,
-    TypeTuple,
-    TypeTupleMember,
-    TypeStaticArray,
-    TypeStaticArrayMember,
-)
+from .type3 import types as type3types
 
-from . import codestyle
 from .exceptions import StaticError
 from .ourlang import (
-    WEBASSEMBLY_BUILDIN_FLOAT_OPS,
+    WEBASSEMBLY_BUILTIN_FLOAT_OPS,
 
     Module, ModuleDataBlock,
     Function,
 
     Expression,
-    AccessBytesIndex, AccessStructMember, AccessTupleMember, AccessStaticArrayMember,
     BinaryOp,
-    Constant,
-    ConstantFloat32, ConstantFloat64, ConstantInt32, ConstantInt64,
-    ConstantUInt8, ConstantUInt32, ConstantUInt64,
-    ConstantTuple, ConstantStaticArray,
+    ConstantPrimitive, ConstantTuple, ConstantStruct,
+    TupleInstantiation,
 
-    FunctionCall,
-    StructConstructor, TupleConstructor,
+    FunctionCall, AccessStructMember, Subscript,
+    StructDefinition, StructConstructor,
     UnaryOp, VariableReference,
 
-    Fold, ModuleConstantReference,
+    Fold,
 
     Statement,
     StatementIf, StatementPass, StatementReturn,
 
+    FunctionParam,
     ModuleConstantDef,
 )
 
@@ -60,7 +41,7 @@ def phasm_parse(source: str) -> Module:
     our_visitor = OurVisitor()
     return our_visitor.visit_Module(res)
 
-OurLocals = Dict[str, TypeBase]
+OurLocals = Dict[str, Union[FunctionParam]] # FIXME: Does it become easier if we add ModuleConstantDef to this dict?
 
 class OurVisitor:
     """
@@ -95,14 +76,14 @@ class OurVisitor:
 
                 module.constant_defs[res.name] = res
 
-            if isinstance(res, TypeStruct):
-                if res.name in module.structs:
+            if isinstance(res, StructDefinition):
+                if res.struct_type3.name in module.struct_definitions:
                     raise StaticError(
-                        f'{res.name} already defined on line {module.structs[res.name].lineno}'
+                        f'{res.struct_type3.name} already defined on line {module.struct_definitions[res.struct_type3.name].lineno}'
                     )
 
-                module.structs[res.name] = res
-                constructor = StructConstructor(res)
+                module.struct_definitions[res.struct_type3.name] = res
+                constructor = StructConstructor(res.struct_type3)
                 module.functions[constructor.name] = constructor
 
             if isinstance(res, Function):
@@ -120,7 +101,7 @@ class OurVisitor:
 
         return module
 
-    def pre_visit_Module_stmt(self, module: Module, node: ast.stmt) -> Union[Function, TypeStruct, ModuleConstantDef]:
+    def pre_visit_Module_stmt(self, module: Module, node: ast.stmt) -> Union[Function, StructDefinition, ModuleConstantDef]:
         if isinstance(node, ast.FunctionDef):
             return self.pre_visit_Module_FunctionDef(module, node)
 
@@ -138,12 +119,9 @@ class OurVisitor:
         _not_implemented(not node.args.posonlyargs, 'FunctionDef.args.posonlyargs')
 
         for arg in node.args.args:
-            if not arg.annotation:
-                _raise_static_error(node, 'Type is required')
-
-            function.posonlyargs.append((
+            function.posonlyargs.append(FunctionParam(
                 arg.arg,
-                self.visit_type(module, arg.annotation),
+                self.visit_type(module, arg.annotation) if arg.annotation else None,
             ))
 
         _not_implemented(not node.args.vararg, 'FunctionDef.args.vararg')
@@ -166,21 +144,23 @@ class OurVisitor:
             else:
                 function.imported = True
 
-        if node.returns:
-            function.returns = self.visit_type(module, node.returns)
+        if node.returns is not None: # Note: `-> None` would be a ast.Constant
+            function.returns_type3 = self.visit_type(module, node.returns)
+        else:
+            # FIXME: Mostly works already, needs to fix Function.returns_type3 and have it updated
+            raise NotImplementedError('Function without an explicit return type')
 
         _not_implemented(not node.type_comment, 'FunctionDef.type_comment')
 
         return function
 
-    def pre_visit_Module_ClassDef(self, module: Module, node: ast.ClassDef) -> TypeStruct:
-        struct = TypeStruct(node.name, node.lineno)
+    def pre_visit_Module_ClassDef(self, module: Module, node: ast.ClassDef) -> StructDefinition:
 
         _not_implemented(not node.bases, 'ClassDef.bases')
         _not_implemented(not node.keywords, 'ClassDef.keywords')
         _not_implemented(not node.decorator_list, 'ClassDef.decorator_list')
 
-        offset = 0
+        members: Dict[str, type3types.Type3] = {}
 
         for stmt in node.body:
             if not isinstance(stmt, ast.AnnAssign):
@@ -195,47 +175,36 @@ class OurVisitor:
             if stmt.simple != 1:
                 raise NotImplementedError('Class with non-simple arguments')
 
-            member = TypeStructMember(stmt.target.id, self.visit_type(module, stmt.annotation), offset)
+            if stmt.target.id in members:
+                _raise_static_error(stmt, 'Struct members must have unique names')
 
-            struct.members.append(member)
-            offset += member.type.alloc_size()
+            members[stmt.target.id] = self.visit_type(module, stmt.annotation)
 
-        return struct
+        return StructDefinition(type3types.StructType3(node.name, members), node.lineno)
 
     def pre_visit_Module_AnnAssign(self, module: Module, node: ast.AnnAssign) -> ModuleConstantDef:
         if not isinstance(node.target, ast.Name):
-            _raise_static_error(node, 'Must be name')
+            _raise_static_error(node.target, 'Must be name')
         if not isinstance(node.target.ctx, ast.Store):
-            _raise_static_error(node, 'Must be load context')
+            _raise_static_error(node.target, 'Must be store context')
 
-        exp_type = self.visit_type(module, node.annotation)
-
-        if isinstance(exp_type, TypeInt32):
-            if not isinstance(node.value, ast.Constant):
-                _raise_static_error(node, 'Must be constant')
-
-            constant = ModuleConstantDef(
+        if isinstance(node.value, ast.Constant):
+            type3 = self.visit_type(module, node.annotation)
+            return ModuleConstantDef(
                 node.target.id,
                 node.lineno,
-                exp_type,
-                self.visit_Module_Constant(module, exp_type, node.value),
+                type3,
+                self.visit_Module_Constant(module, node.value),
                 None,
             )
-            return constant
-
-        if isinstance(exp_type, TypeTuple):
-            if not isinstance(node.value, ast.Tuple):
-                _raise_static_error(node, 'Must be tuple')
-
-            if len(exp_type.members) != len(node.value.elts):
-                _raise_static_error(node, 'Invalid number of tuple values')
 
+        if isinstance(node.value, ast.Tuple):
             tuple_data = [
-                self.visit_Module_Constant(module, mem.type, arg_node)
-                for arg_node, mem in zip(node.value.elts, exp_type.members)
+                self.visit_Module_Constant(module, arg_node)
+                for arg_node in node.value.elts
                 if isinstance(arg_node, ast.Constant)
             ]
-            if len(exp_type.members) != len(tuple_data):
+            if len(node.value.elts) != len(tuple_data):
                 _raise_static_error(node, 'Tuple arguments must be constants')
 
             # Allocate the data
@@ -246,36 +215,47 @@ class OurVisitor:
             return ModuleConstantDef(
                 node.target.id,
                 node.lineno,
-                exp_type,
-                ConstantTuple(exp_type, tuple_data),
+                self.visit_type(module, node.annotation),
+                ConstantTuple(tuple_data),
                 data_block,
             )
 
-        if isinstance(exp_type, TypeStaticArray):
-            if not isinstance(node.value, ast.Tuple):
-                _raise_static_error(node, 'Must be static array')
+        if isinstance(node.value, ast.Call):
+            # Struct constant
+            # Stored in memory like a tuple, so much of the code is the same
 
-            if len(exp_type.members) != len(node.value.elts):
-                _raise_static_error(node, 'Invalid number of static array values')
+            if not isinstance(node.value.func, ast.Name):
+                _raise_static_error(node.value.func, 'Must be name')
+            if not isinstance(node.value.func.ctx, ast.Load):
+                _raise_static_error(node.value.func, 'Must be load context')
 
-            static_array_data = [
-                self.visit_Module_Constant(module, exp_type.member_type, arg_node)
-                for arg_node in node.value.elts
+            if not node.value.func.id in module.struct_definitions:
+                _raise_static_error(node.value.func, 'Undefined struct')
+
+            if node.value.keywords:
+                _raise_static_error(node.value.func, 'Cannot use keywords')
+
+            if not isinstance(node.annotation, ast.Name):
+                _raise_static_error(node.annotation, 'Must be name')
+
+            struct_data = [
+                self.visit_Module_Constant(module, arg_node)
+                for arg_node in node.value.args
                 if isinstance(arg_node, ast.Constant)
             ]
-            if len(exp_type.members) != len(static_array_data):
-                _raise_static_error(node, 'Static array arguments must be constants')
+            if len(node.value.args) != len(struct_data):
+                _raise_static_error(node, 'Struct arguments must be constants')
 
             # Allocate the data
-            data_block = ModuleDataBlock(static_array_data)
+            data_block = ModuleDataBlock(struct_data)
             module.data.blocks.append(data_block)
 
             # Then return the constant as a pointer
             return ModuleConstantDef(
                 node.target.id,
                 node.lineno,
-                exp_type,
-                ConstantStaticArray(exp_type, static_array_data),
+                self.visit_type(module, node.annotation),
+                ConstantStruct(node.value.func.id, struct_data),
                 data_block,
             )
 
@@ -297,7 +277,10 @@ class OurVisitor:
     def visit_Module_FunctionDef(self, module: Module, node: ast.FunctionDef) -> None:
         function = module.functions[node.name]
 
-        our_locals = dict(function.posonlyargs)
+        our_locals: OurLocals = {
+            x.name: x
+            for x in function.posonlyargs
+        }
 
         for stmt in node.body:
             function.statements.append(
@@ -311,12 +294,12 @@ class OurVisitor:
                 _raise_static_error(node, 'Return must have an argument')
 
             return StatementReturn(
-                self.visit_Module_FunctionDef_expr(module, function, our_locals, function.returns, node.value)
+                self.visit_Module_FunctionDef_expr(module, function, our_locals, node.value)
             )
 
         if isinstance(node, ast.If):
             result = StatementIf(
-                self.visit_Module_FunctionDef_expr(module, function, our_locals, function.returns, node.test)
+                self.visit_Module_FunctionDef_expr(module, function, our_locals, node.test)
             )
 
             for stmt in node.body:
@@ -336,7 +319,7 @@ class OurVisitor:
 
         raise NotImplementedError(f'{node} as stmt in FunctionDef')
 
-    def visit_Module_FunctionDef_expr(self, module: Module, function: Function, our_locals: OurLocals, exp_type: TypeBase, node: ast.expr) -> Expression:
+    def visit_Module_FunctionDef_expr(self, module: Module, function: Function, our_locals: OurLocals, node: ast.expr) -> Expression:
         if isinstance(node, ast.BinOp):
             if isinstance(node.op, ast.Add):
                 operator = '+'
@@ -344,6 +327,8 @@ class OurVisitor:
                 operator = '-'
             elif isinstance(node.op, ast.Mult):
                 operator = '*'
+            elif isinstance(node.op, ast.Div):
+                operator = '/'
             elif isinstance(node.op, ast.LShift):
                 operator = '<<'
             elif isinstance(node.op, ast.RShift):
@@ -357,14 +342,10 @@ class OurVisitor:
             else:
                 raise NotImplementedError(f'Operator {node.op}')
 
-            # Assume the type doesn't change when descending into a binary operator
-            # e.g. you can do `"hello" * 3` with the code below (yet)
-
             return BinaryOp(
-                exp_type,
                 operator,
-                self.visit_Module_FunctionDef_expr(module, function, our_locals, exp_type, node.left),
-                self.visit_Module_FunctionDef_expr(module, function, our_locals, exp_type, node.right),
+                self.visit_Module_FunctionDef_expr(module, function, our_locals, node.left),
+                self.visit_Module_FunctionDef_expr(module, function, our_locals, node.right),
             )
 
         if isinstance(node, ast.UnaryOp):
@@ -376,9 +357,8 @@ class OurVisitor:
                 raise NotImplementedError(f'Operator {node.op}')
 
             return UnaryOp(
-                exp_type,
                 operator,
-                self.visit_Module_FunctionDef_expr(module, function, our_locals, exp_type, node.operand),
+                self.visit_Module_FunctionDef_expr(module, function, our_locals, node.operand),
             )
 
         if isinstance(node, ast.Compare):
@@ -394,32 +374,28 @@ class OurVisitor:
             else:
                 raise NotImplementedError(f'Operator {node.ops}')
 
-            # Assume the type doesn't change when descending into a binary operator
-            # e.g. you can do `"hello" * 3` with the code below (yet)
-
             return BinaryOp(
-                exp_type,
                 operator,
-                self.visit_Module_FunctionDef_expr(module, function, our_locals, exp_type, node.left),
-                self.visit_Module_FunctionDef_expr(module, function, our_locals, exp_type, node.comparators[0]),
+                self.visit_Module_FunctionDef_expr(module, function, our_locals, node.left),
+                self.visit_Module_FunctionDef_expr(module, function, our_locals, node.comparators[0]),
             )
 
         if isinstance(node, ast.Call):
-            return self.visit_Module_FunctionDef_Call(module, function, our_locals, exp_type, node)
+            return self.visit_Module_FunctionDef_Call(module, function, our_locals, node)
 
         if isinstance(node, ast.Constant):
             return self.visit_Module_Constant(
-                module, exp_type, node,
+                module, node,
             )
 
         if isinstance(node, ast.Attribute):
             return self.visit_Module_FunctionDef_Attribute(
-                module, function, our_locals, exp_type, node,
+                module, function, our_locals, node,
             )
 
         if isinstance(node, ast.Subscript):
             return self.visit_Module_FunctionDef_Subscript(
-                module, function, our_locals, exp_type, node,
+                module, function, our_locals, node,
             )
 
         if isinstance(node, ast.Name):
@@ -427,45 +403,30 @@ class OurVisitor:
                 _raise_static_error(node, 'Must be load context')
 
             if node.id in our_locals:
-                act_type = our_locals[node.id]
-                if exp_type != act_type:
-                    _raise_static_error(node, f'Expected {codestyle.type_(exp_type)}, {node.id} is actually {codestyle.type_(act_type)}')
-
-                return VariableReference(act_type, node.id)
+                param = our_locals[node.id]
+                return VariableReference(param)
 
             if node.id in module.constant_defs:
                 cdef = module.constant_defs[node.id]
-                if exp_type != cdef.type:
-                    _raise_static_error(node, f'Expected {codestyle.type_(exp_type)}, {node.id} is actually {codestyle.type_(cdef.type)}')
-
-                return ModuleConstantReference(exp_type, cdef)
+                return VariableReference(cdef)
 
             _raise_static_error(node, f'Undefined variable {node.id}')
 
         if isinstance(node, ast.Tuple):
-            if not isinstance(node.ctx, ast.Load):
-                _raise_static_error(node, 'Must be load context')
+            arguments = [
+                self.visit_Module_FunctionDef_expr(module, function, our_locals, arg_node)
+                for arg_node in node.elts
+                if isinstance(arg_node, ast.Constant)
+            ]
 
-            if isinstance(exp_type, TypeTuple):
-                if len(exp_type.members) != len(node.elts):
-                    _raise_static_error(node, f'Expression is expecting a tuple of size {len(exp_type.members)}, but {len(node.elts)} are given')
+            if len(arguments) != len(node.elts):
+                raise NotImplementedError('Non-constant tuple members')
 
-                tuple_constructor = TupleConstructor(exp_type)
-
-                func = module.functions[tuple_constructor.name]
-
-                result = FunctionCall(func)
-                result.arguments = [
-                    self.visit_Module_FunctionDef_expr(module, function, our_locals, mem.type, arg_node)
-                    for arg_node, mem in zip(node.elts, exp_type.members)
-                ]
-                return result
-
-            _raise_static_error(node, f'Expression is expecting a {codestyle.type_(exp_type)}, not a tuple')
+            return TupleInstantiation(arguments)
 
         raise NotImplementedError(f'{node} as expr in FunctionDef')
 
-    def visit_Module_FunctionDef_Call(self, module: Module, function: Function, our_locals: OurLocals, exp_type: TypeBase, node: ast.Call) -> Union[Fold, FunctionCall, UnaryOp]:
+    def visit_Module_FunctionDef_Call(self, module: Module, function: Function, our_locals: OurLocals, node: ast.Call) -> Union[Fold, FunctionCall, UnaryOp]:
         if node.keywords:
             _raise_static_error(node, 'Keyword calling not supported') # Yet?
 
@@ -474,59 +435,42 @@ class OurVisitor:
         if not isinstance(node.func.ctx, ast.Load):
             _raise_static_error(node, 'Must be load context')
 
-        if node.func.id in module.structs:
-            struct = module.structs[node.func.id]
-            struct_constructor = StructConstructor(struct)
+        if node.func.id in module.struct_definitions:
+            struct_definition = module.struct_definitions[node.func.id]
+            struct_constructor = StructConstructor(struct_definition.struct_type3)
+
+            # FIXME: Defer struct de-allocation
 
             func = module.functions[struct_constructor.name]
-        elif node.func.id in WEBASSEMBLY_BUILDIN_FLOAT_OPS:
-            if not isinstance(exp_type, (TypeFloat32, TypeFloat64, )):
-                _raise_static_error(node, f'Cannot make {node.func.id} result in {codestyle.type_(exp_type)}')
-
+        elif node.func.id in WEBASSEMBLY_BUILTIN_FLOAT_OPS:
             if 1 != len(node.args):
                 _raise_static_error(node, f'Function {node.func.id} requires 1 arguments but {len(node.args)} are given')
 
             return UnaryOp(
-                exp_type,
                 'sqrt',
-                self.visit_Module_FunctionDef_expr(module, function, our_locals, exp_type, node.args[0]),
+                self.visit_Module_FunctionDef_expr(module, function, our_locals, node.args[0]),
             )
         elif node.func.id == 'u32':
-            if not isinstance(exp_type, TypeUInt32):
-                _raise_static_error(node, f'Cannot make {node.func.id} result in {exp_type}')
-
             if 1 != len(node.args):
                 _raise_static_error(node, f'Function {node.func.id} requires 1 arguments but {len(node.args)} are given')
 
-            # FIXME: This is a stub, proper casting is todo
-
             return UnaryOp(
-                exp_type,
                 'cast',
-                self.visit_Module_FunctionDef_expr(module, function, our_locals, module.types['u8'], node.args[0]),
+                self.visit_Module_FunctionDef_expr(module, function, our_locals, node.args[0]),
             )
         elif node.func.id == 'len':
-            if not isinstance(exp_type, TypeInt32):
-                _raise_static_error(node, f'Cannot make {node.func.id} result in {exp_type}')
-
             if 1 != len(node.args):
                 _raise_static_error(node, f'Function {node.func.id} requires 1 arguments but {len(node.args)} are given')
 
             return UnaryOp(
-                exp_type,
                 'len',
-                self.visit_Module_FunctionDef_expr(module, function, our_locals, module.types['bytes'], node.args[0]),
+                self.visit_Module_FunctionDef_expr(module, function, our_locals, node.args[0]),
             )
         elif node.func.id == 'foldl':
-            # TODO: This should a much more generic function!
-            # For development purposes, we're assuming you're doing a foldl(Callable[[u8, u8], u8], u8, bytes)
-            # In the future, we should probably infer the type of the second argument,
-            # and use it as expected types for the other u8s and the Iterable[u8] (i.e. bytes)
-
             if 3 != len(node.args):
                 _raise_static_error(node, f'Function {node.func.id} requires 3 arguments but {len(node.args)} are given')
 
-            # TODO: This is not generic
+            # TODO: This is not generic, you cannot return a function
             subnode = node.args[0]
             if not isinstance(subnode, ast.Name):
                 raise NotImplementedError(f'Calling methods that are not a name {subnode}')
@@ -538,21 +482,11 @@ class OurVisitor:
             if 2 != len(func.posonlyargs):
                 _raise_static_error(node, f'Function {node.func.id} requires a function with 2 arguments but a function with {len(func.posonlyargs)} args is given')
 
-            if exp_type.__class__ != func.returns.__class__:
-                _raise_static_error(node, f'Expected {codestyle.type_(exp_type)}, {func.name} actually returns {codestyle.type_(func.returns)}')
-
-            if func.returns.__class__ != func.posonlyargs[0][1].__class__:
-                _raise_static_error(node, f'Expected a foldable function, {func.name} returns a {codestyle.type_(func.returns)} but expects a {codestyle.type_(func.posonlyargs[0][1])}')
-
-            if module.types['u8'].__class__ != func.posonlyargs[1][1].__class__:
-                _raise_static_error(node, 'Only folding over bytes (u8) is supported at this time')
-
             return Fold(
-                exp_type,
                 Fold.Direction.LEFT,
                 func,
-                self.visit_Module_FunctionDef_expr(module, function, our_locals, func.returns, node.args[1]),
-                self.visit_Module_FunctionDef_expr(module, function, our_locals, module.types['bytes'], node.args[2]),
+                self.visit_Module_FunctionDef_expr(module, function, our_locals, node.args[1]),
+                self.visit_Module_FunctionDef_expr(module, function, our_locals, node.args[2]),
             )
         else:
             if node.func.id not in module.functions:
@@ -560,206 +494,76 @@ class OurVisitor:
 
             func = module.functions[node.func.id]
 
-        if func.returns != exp_type:
-            _raise_static_error(node, f'Expected {codestyle.type_(exp_type)}, {func.name} actually returns {codestyle.type_(func.returns)}')
-
         if len(func.posonlyargs) != len(node.args):
             _raise_static_error(node, f'Function {node.func.id} requires {len(func.posonlyargs)} arguments but {len(node.args)} are given')
 
         result = FunctionCall(func)
         result.arguments.extend(
-            self.visit_Module_FunctionDef_expr(module, function, our_locals, arg_type, arg_expr)
-            for arg_expr, (_, arg_type) in zip(node.args, func.posonlyargs)
+            self.visit_Module_FunctionDef_expr(module, function, our_locals, arg_expr)
+            for arg_expr, param in zip(node.args, func.posonlyargs)
         )
         return result
 
-    def visit_Module_FunctionDef_Attribute(self, module: Module, function: Function, our_locals: OurLocals, exp_type: TypeBase, node: ast.Attribute) -> Expression:
-        del module
-        del function
-
+    def visit_Module_FunctionDef_Attribute(self, module: Module, function: Function, our_locals: OurLocals, node: ast.Attribute) -> Expression:
         if not isinstance(node.value, ast.Name):
             _raise_static_error(node, 'Must reference a name')
 
         if not isinstance(node.ctx, ast.Load):
             _raise_static_error(node, 'Must be load context')
 
-        if not node.value.id in our_locals:
-            _raise_static_error(node, f'Undefined variable {node.value.id}')
+        varref = self.visit_Module_FunctionDef_expr(module, function, our_locals, node.value)
+        if not isinstance(varref, VariableReference):
+            _raise_static_error(node.value, 'Must refer to variable')
 
-        node_typ = our_locals[node.value.id]
-        if not isinstance(node_typ, TypeStruct):
-            _raise_static_error(node, f'Cannot take attribute of non-struct {node.value.id}')
-
-        member = node_typ.get_member(node.attr)
-        if member is None:
-            _raise_static_error(node, f'{node_typ.name} has no attribute {node.attr}')
-
-        if exp_type != member.type:
-            _raise_static_error(node, f'Expected {codestyle.type_(exp_type)}, {node.value.id}.{member.name} is actually {codestyle.type_(member.type)}')
+        if not isinstance(varref.variable.type3, type3types.StructType3):
+            _raise_static_error(node.value, 'Must refer to struct')
 
         return AccessStructMember(
-            VariableReference(node_typ, node.value.id),
-            member,
+            varref,
+            varref.variable.type3,
+            node.attr,
         )
 
-    def visit_Module_FunctionDef_Subscript(self, module: Module, function: Function, our_locals: OurLocals, exp_type: TypeBase, node: ast.Subscript) -> Expression:
+    def visit_Module_FunctionDef_Subscript(self, module: Module, function: Function, our_locals: OurLocals, node: ast.Subscript) -> Expression:
         if not isinstance(node.value, ast.Name):
             _raise_static_error(node, 'Must reference a name')
 
-        if not isinstance(node.slice, ast.Index):
+        if isinstance(node.slice, ast.Slice):
             _raise_static_error(node, 'Must subscript using an index')
 
         if not isinstance(node.ctx, ast.Load):
             _raise_static_error(node, 'Must be load context')
 
-        varref: Union[ModuleConstantReference, VariableReference]
+        varref: VariableReference
         if node.value.id in our_locals:
-            node_typ = our_locals[node.value.id]
-            varref = VariableReference(node_typ, node.value.id)
+            param = our_locals[node.value.id]
+            varref = VariableReference(param)
         elif node.value.id in module.constant_defs:
             constant_def = module.constant_defs[node.value.id]
-            node_typ = constant_def.type
-            varref = ModuleConstantReference(node_typ, constant_def)
+            varref = VariableReference(constant_def)
         else:
             _raise_static_error(node, f'Undefined variable {node.value.id}')
 
         slice_expr = self.visit_Module_FunctionDef_expr(
-            module, function, our_locals, module.types['u32'], node.slice.value,
+            module, function, our_locals, node.slice,
         )
 
-        if isinstance(node_typ, TypeBytes):
-            t_u8 = module.types['u8']
-            if exp_type != t_u8:
-                _raise_static_error(node, f'Expected {codestyle.type_(exp_type)}, {node.value.id}[{codestyle.expression(slice_expr)}] is actually {codestyle.type_(t_u8)}')
+        return Subscript(varref, slice_expr)
 
-            if isinstance(varref, ModuleConstantReference):
-                raise NotImplementedError(f'{node} from module constant')
-
-            return AccessBytesIndex(
-                t_u8,
-                varref,
-                slice_expr,
-            )
-
-        if isinstance(node_typ, TypeTuple):
-            if not isinstance(slice_expr, ConstantUInt32):
-                _raise_static_error(node, 'Must subscript using a constant index')
-
-            idx = slice_expr.value
-
-            if len(node_typ.members) <= idx:
-                _raise_static_error(node, f'Index {idx} out of bounds for tuple {node.value.id}')
-
-            tuple_member = node_typ.members[idx]
-            if exp_type != tuple_member.type:
-                _raise_static_error(node, f'Expected {codestyle.type_(exp_type)}, {node.value.id}[{idx}] is actually {codestyle.type_(tuple_member.type)}')
-
-            if isinstance(varref, ModuleConstantReference):
-                raise NotImplementedError(f'{node} from module constant')
-
-            return AccessTupleMember(
-                varref,
-                tuple_member,
-            )
-
-        if isinstance(node_typ, TypeStaticArray):
-            if exp_type != node_typ.member_type:
-                _raise_static_error(node, f'Expected {codestyle.type_(exp_type)}, {node.value.id}[{idx}] is actually {codestyle.type_(node_typ.member_type)}')
-
-            if not isinstance(slice_expr, ConstantInt32):
-                return AccessStaticArrayMember(
-                    varref,
-                    node_typ,
-                    slice_expr,
-                )
-
-            idx = slice_expr.value
-
-            if len(node_typ.members) <= idx:
-                _raise_static_error(node, f'Index {idx} out of bounds for static array {node.value.id}')
-
-            static_array_member = node_typ.members[idx]
-
-            return AccessStaticArrayMember(
-                varref,
-                node_typ,
-                static_array_member,
-            )
-
-        _raise_static_error(node, f'Cannot take index of {node_typ} {node.value.id}')
-
-    def visit_Module_Constant(self, module: Module, exp_type: TypeBase, node: ast.Constant) -> Constant:
+    def visit_Module_Constant(self, module: Module, node: ast.Constant) -> ConstantPrimitive:
         del module
 
         _not_implemented(node.kind is None, 'Constant.kind')
 
-        if isinstance(exp_type, TypeUInt8):
-            if not isinstance(node.value, int):
-                _raise_static_error(node, 'Expected integer value')
+        if isinstance(node.value, (int, float, )):
+            return ConstantPrimitive(node.value)
 
-            if node.value < 0 or node.value > 255:
-                _raise_static_error(node, f'Integer value out of range; expected 0..255, actual {node.value}')
+        raise NotImplementedError(f'{node.value} as constant')
 
-            return ConstantUInt8(exp_type, node.value)
-
-        if isinstance(exp_type, TypeUInt32):
-            if not isinstance(node.value, int):
-                _raise_static_error(node, 'Expected integer value')
-
-            if node.value < 0 or node.value > 4294967295:
-                _raise_static_error(node, 'Integer value out of range')
-
-            return ConstantUInt32(exp_type, node.value)
-
-        if isinstance(exp_type, TypeUInt64):
-            if not isinstance(node.value, int):
-                _raise_static_error(node, 'Expected integer value')
-
-            if node.value < 0 or node.value > 18446744073709551615:
-                _raise_static_error(node, 'Integer value out of range')
-
-            return ConstantUInt64(exp_type, node.value)
-
-        if isinstance(exp_type, TypeInt32):
-            if not isinstance(node.value, int):
-                _raise_static_error(node, 'Expected integer value')
-
-            if node.value < -2147483648 or node.value > 2147483647:
-                _raise_static_error(node, 'Integer value out of range')
-
-            return ConstantInt32(exp_type, node.value)
-
-        if isinstance(exp_type, TypeInt64):
-            if not isinstance(node.value, int):
-                _raise_static_error(node, 'Expected integer value')
-
-            if node.value < -9223372036854775808 or node.value > 9223372036854775807:
-                _raise_static_error(node, 'Integer value out of range')
-
-            return ConstantInt64(exp_type, node.value)
-
-        if isinstance(exp_type, TypeFloat32):
-            if not isinstance(node.value, (float, int, )):
-                _raise_static_error(node, 'Expected float value')
-
-            # FIXME: Range check
-
-            return ConstantFloat32(exp_type, node.value)
-
-        if isinstance(exp_type, TypeFloat64):
-            if not isinstance(node.value, (float, int, )):
-                _raise_static_error(node, 'Expected float value')
-
-            # FIXME: Range check
-
-            return ConstantFloat64(exp_type, node.value)
-
-        raise NotImplementedError(f'{node} as const for type {exp_type}')
-
-    def visit_type(self, module: Module, node: ast.expr) -> TypeBase:
+    def visit_type(self, module: Module, node: ast.expr) -> type3types.Type3:
         if isinstance(node, ast.Constant):
             if node.value is None:
-                return module.types['None']
+                return type3types.none
 
             _raise_static_error(node, f'Unrecognized type {node.value}')
 
@@ -767,70 +571,42 @@ class OurVisitor:
             if not isinstance(node.ctx, ast.Load):
                 _raise_static_error(node, 'Must be load context')
 
-            if node.id in module.types:
-                return module.types[node.id]
+            if node.id in type3types.LOOKUP_TABLE:
+                return type3types.LOOKUP_TABLE[node.id]
 
-            if node.id in module.structs:
-                return module.structs[node.id]
+            if node.id in module.struct_definitions:
+                return module.struct_definitions[node.id].struct_type3
 
             _raise_static_error(node, f'Unrecognized type {node.id}')
 
         if isinstance(node, ast.Subscript):
             if not isinstance(node.value, ast.Name):
                 _raise_static_error(node, 'Must be name')
-            if not isinstance(node.slice, ast.Index):
+            if isinstance(node.slice, ast.Slice):
                 _raise_static_error(node, 'Must subscript using an index')
-            if not isinstance(node.slice.value, ast.Constant):
+            if not isinstance(node.slice, ast.Constant):
                 _raise_static_error(node, 'Must subscript using a constant index')
-            if not isinstance(node.slice.value.value, int):
+            if not isinstance(node.slice.value, int):
                 _raise_static_error(node, 'Must subscript using a constant integer index')
             if not isinstance(node.ctx, ast.Load):
                 _raise_static_error(node, 'Must be load context')
 
-            if node.value.id in module.types:
-                member_type = module.types[node.value.id]
-            else:
+            if node.value.id not in type3types.LOOKUP_TABLE: # FIXME: Tuple of tuples?
                 _raise_static_error(node, f'Unrecognized type {node.value.id}')
 
-            type_static_array = TypeStaticArray(member_type)
-
-            offset = 0
-
-            for idx in range(node.slice.value.value):
-                static_array_member = TypeStaticArrayMember(idx, offset)
-
-                type_static_array.members.append(static_array_member)
-                offset += member_type.alloc_size()
-
-            key = f'{node.value.id}[{node.slice.value.value}]'
-
-            if key not in module.types:
-                module.types[key] = type_static_array
-
-            return module.types[key]
+            return type3types.AppliedType3(
+                type3types.static_array,
+                [self.visit_type(module, node.value), type3types.IntType3(node.slice.value)],
+            )
 
         if isinstance(node, ast.Tuple):
             if not isinstance(node.ctx, ast.Load):
                 _raise_static_error(node, 'Must be load context')
 
-            type_tuple = TypeTuple()
-
-            offset = 0
-
-            for idx, elt in enumerate(node.elts):
-                tuple_member = TypeTupleMember(idx, self.visit_type(module, elt), offset)
-
-                type_tuple.members.append(tuple_member)
-                offset += tuple_member.type.alloc_size()
-
-            key = type_tuple.render_internal_name()
-
-            if key not in module.types:
-                module.types[key] = type_tuple
-                constructor = TupleConstructor(type_tuple)
-                module.functions[constructor.name] = constructor
-
-            return module.types[key]
+            return type3types.AppliedType3(
+                type3types.tuple,
+                (self.visit_type(module, elt) for elt in node.elts)
+            )
 
         raise NotImplementedError(f'{node} as type')
 
diff --git a/phasm/stdlib/alloc.py b/phasm/stdlib/alloc.py
index 2761bfb..8c5742d 100644
--- a/phasm/stdlib/alloc.py
+++ b/phasm/stdlib/alloc.py
@@ -26,7 +26,7 @@ def __find_free_block__(g: Generator, alloc_size: i32) -> i32:
         g.i32.const(0)
         g.return_()
 
-    del alloc_size # TODO
+    del alloc_size # TODO: Actual implement using a previously freed block
     g.unreachable()
 
     return i32('return') # To satisfy mypy
diff --git a/phasm/type3/__init__.py b/phasm/type3/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/phasm/type3/constraints.py b/phasm/type3/constraints.py
new file mode 100644
index 0000000..31b8f20
--- /dev/null
+++ b/phasm/type3/constraints.py
@@ -0,0 +1,549 @@
+"""
+This module contains possible constraints generated based on the AST
+
+These need to be resolved before the program can be compiled.
+"""
+from typing import Dict, Optional, List, Tuple, Union
+
+from .. import ourlang
+
+from . import types
+
+class Error:
+    """
+    An error returned by the check functions for a contraint
+
+    This means the programmer has to make some kind of chance to the
+    typing of their program before the compiler can do its thing.
+    """
+    def __init__(self, msg: str) -> None:
+        self.msg = msg
+
+    def __repr__(self) -> str:
+        return f'Error({repr(self.msg)})'
+
+class RequireTypeSubstitutes:
+    """
+    Returned by the check function for a contraint if they do not have all
+    their types substituted yet.
+
+    Hopefully, another constraint will give the right information about the
+    typing of the program, so this constraint can be updated.
+    """
+
+SubstitutionMap = Dict[types.PlaceholderForType, types.Type3]
+
+NewConstraintList = List['ConstraintBase']
+
+CheckResult = Union[None, SubstitutionMap, Error, NewConstraintList, RequireTypeSubstitutes]
+
+HumanReadableRet = Tuple[str, Dict[str, Union[str, ourlang.Expression, types.Type3, types.PlaceholderForType]]]
+
+class Context:
+    """
+    Context for constraints
+    """
+
+    __slots__ = ()
+
+class ConstraintBase:
+    """
+    Base class for constraints
+    """
+    __slots__ = ('comment', )
+
+    comment: Optional[str]
+    """
+    A comment to help the programmer with debugging the types in their program
+    """
+
+    def __init__(self, comment: Optional[str] = None) -> None:
+        self.comment = comment
+
+    def check(self) -> CheckResult:
+        """
+        Checks if the constraint hold
+
+        This function can return an error, if the constraint does not hold,
+        which indicates an error in the typing of the input program.
+
+        This function can return RequireTypeSubstitutes(), if we cannot deduce
+        all the types yet.
+
+        This function can return a SubstitutionMap, if during the evaluation
+        of the contraint we discovered new types. In this case, the constraint
+        is expected to hold.
+
+        This function can return None, if the constraint holds, but no new
+        information was deduced from evaluating this constraint.
+        """
+        raise NotImplementedError(self.__class__, self.check)
+
+    def human_readable(self) -> HumanReadableRet:
+        """
+        Returns a more human readable form of this constraint
+        """
+        return repr(self), {}
+
+class SameTypeConstraint(ConstraintBase):
+    """
+    Verifies that a number of types all are the same type
+    """
+    __slots__ = ('type_list', )
+
+    type_list: List[types.Type3OrPlaceholder]
+
+    def __init__(self, *type_list: types.Type3OrPlaceholder, comment: Optional[str] = None) -> None:
+        super().__init__(comment=comment)
+
+        assert len(type_list) > 1
+        self.type_list = [*type_list]
+
+    def check(self) -> CheckResult:
+        known_types: List[types.Type3] = []
+        placeholders = []
+        do_applied_placeholder_check: bool = False
+        for typ in self.type_list:
+            if isinstance(typ, types.IntType3):
+                known_types.append(typ)
+                continue
+
+            if isinstance(typ, (types.PrimitiveType3, types.StructType3, )):
+                known_types.append(typ)
+                continue
+
+            if isinstance(typ, types.AppliedType3):
+                known_types.append(typ)
+                do_applied_placeholder_check = True                    
+                continue
+
+            if isinstance(typ, types.PlaceholderForType):
+                if typ.resolve_as is not None:
+                    known_types.append(typ.resolve_as)
+                else:
+                    placeholders.append(typ)
+                continue
+
+            raise NotImplementedError(typ)
+
+        if not known_types:
+            return RequireTypeSubstitutes()
+
+        new_constraint_list: List[ConstraintBase] = []
+
+        first_type = known_types[0]
+        for typ in known_types[1:]:
+            if isinstance(first_type, types.AppliedType3) and isinstance(typ, types.AppliedType3):
+                if len(first_type.args) != len(typ.args):
+                    return Error('Mismatch between applied types argument count')
+
+                if first_type.base != typ.base:
+                    return Error('Mismatch between applied types base')
+
+                for first_type_arg, typ_arg in zip(first_type.args, typ.args):
+                    new_constraint_list.append(SameTypeConstraint(
+                        first_type_arg, typ_arg
+                    ))
+
+                continue
+
+            if typ != first_type:
+                return Error(f'{typ:s} must be {first_type:s} instead')
+
+        if new_constraint_list:
+            # If this happens, make CheckResult a class that can have both
+            assert not placeholders, 'Cannot (yet) return both new placeholders and new constraints'
+
+            return new_constraint_list
+
+        if not placeholders:
+            return None
+
+        for typ in placeholders:
+            typ.resolve_as = first_type
+
+        return {
+            typ: first_type
+            for typ in placeholders
+        }
+
+    def human_readable(self) -> HumanReadableRet:
+        return (
+            ' == '.join('{t' + str(idx) + '}' for idx in range(len(self.type_list))),
+            {
+                't' + str(idx): typ
+                for idx, typ in enumerate(self.type_list)
+            },
+        )
+
+    def __repr__(self) -> str:
+        args = ', '.join(repr(x) for x in self.type_list)
+
+        return f'SameTypeConstraint({args}, comment={repr(self.comment)})'
+
+class IntegerCompareConstraint(ConstraintBase):
+    """
+    Verifies that the given IntType3 are in order (<=)
+    """
+    __slots__ = ('int_type3_list', )
+
+    int_type3_list: List[types.IntType3]
+
+    def __init__(self, *int_type3: types.IntType3, comment: Optional[str] = None) -> None:
+        super().__init__(comment=comment)
+
+        assert len(int_type3) > 1
+        self.int_type3_list = [*int_type3]
+
+    def check(self) -> CheckResult:
+        val_list = [x.value for x in self.int_type3_list]
+
+        prev_val = val_list.pop(0)
+        for next_val in val_list:
+            if prev_val > next_val:
+                return Error(f'{prev_val} must be less or equal than {next_val}')
+
+            prev_val = next_val
+
+        return None
+
+    def human_readable(self) -> HumanReadableRet:
+        return (
+            ' <= '.join('{t' + str(idx) + '}' for idx in range(len(self.int_type3_list))),
+            {
+                't' + str(idx): typ
+                for idx, typ in enumerate(self.int_type3_list)
+            },
+        )
+
+    def __repr__(self) -> str:
+        args = ', '.join(repr(x) for x in self.int_type3_list)
+
+        return f'IntegerCompareConstraint({args}, comment={repr(self.comment)})'
+
+class CastableConstraint(ConstraintBase):
+    """
+    A type can be cast to another type
+    """
+    __slots__ = ('from_type3', 'to_type3', )
+
+    from_type3: types.Type3OrPlaceholder
+    to_type3: types.Type3OrPlaceholder
+
+    def __init__(self, from_type3: types.Type3OrPlaceholder, to_type3: types.Type3OrPlaceholder, comment: Optional[str] = None) -> None:
+        super().__init__(comment=comment)
+
+        self.from_type3 = from_type3
+        self.to_type3 = to_type3
+
+    def check(self) -> CheckResult:
+        ftyp = self.from_type3
+        if isinstance(ftyp, types.PlaceholderForType) and ftyp.resolve_as is not None:
+            ftyp = ftyp.resolve_as
+
+        ttyp = self.to_type3
+        if isinstance(ttyp, types.PlaceholderForType) and ttyp.resolve_as is not None:
+            ttyp = ttyp.resolve_as
+
+        if isinstance(ftyp, types.PlaceholderForType) or isinstance(ttyp, types.PlaceholderForType):
+            return RequireTypeSubstitutes()
+
+        if ftyp is types.u8 and ttyp is types.u32:
+            return None
+
+        return Error(f'Cannot cast {ftyp.name} to {ttyp.name}')
+
+    def human_readable(self) -> HumanReadableRet:
+        return (
+            '{to_type3}({from_type3})',
+            {
+                'to_type3': self.to_type3,
+                'from_type3': self.from_type3,
+            },
+        )
+
+    def __repr__(self) -> str:
+        return f'CastableConstraint({repr(self.from_type3)}, {repr(self.to_type3)}, comment={repr(self.comment)})'
+
+class MustImplementTypeClassConstraint(ConstraintBase):
+    """
+    A type must implement a given type class
+    """
+    __slots__ = ('type_class3', 'type3', )
+
+    type_class3: str
+    type3: types.Type3OrPlaceholder
+
+    DATA = {
+        'u8': {'BitWiseOperation', 'BasicMathOperation', 'EqualComparison', 'StrictPartialOrder'},
+        'u32': {'BitWiseOperation', 'BasicMathOperation', 'EqualComparison', 'StrictPartialOrder'},
+        'u64': {'BitWiseOperation', 'BasicMathOperation', 'EqualComparison', 'StrictPartialOrder'},
+        'i32': {'BasicMathOperation', 'EqualComparison', 'StrictPartialOrder'},
+        'i64': {'BasicMathOperation', 'EqualComparison', 'StrictPartialOrder'},
+        'bytes': {'Foldable', 'Sized'},
+        'f32': {'BasicMathOperation', 'FloatingPoint'},
+        'f64': {'BasicMathOperation', 'FloatingPoint'},
+    }
+
+    def __init__(self, type_class3: str, type3: types.Type3OrPlaceholder, comment: Optional[str] = None) -> None:
+        super().__init__(comment=comment)
+
+        self.type_class3 = type_class3
+        self.type3 = type3
+
+    def check(self) -> CheckResult:
+        typ = self.type3
+        if isinstance(typ, types.PlaceholderForType) and typ.resolve_as is not None:
+            typ = typ.resolve_as
+
+        if isinstance(typ, types.PlaceholderForType):
+            return RequireTypeSubstitutes()
+
+        if self.type_class3 in self.__class__.DATA.get(typ.name, set()):
+            return None
+
+        return Error(f'{typ.name} does not implement the {self.type_class3} type class')
+
+    def human_readable(self) -> HumanReadableRet:
+        return (
+            '{type3} derives {type_class3}',
+            {
+                'type_class3': self.type_class3,
+                'type3': self.type3,
+            },
+        )
+
+    def __repr__(self) -> str:
+        return f'MustImplementTypeClassConstraint({repr(self.type_class3)}, {repr(self.type3)}, comment={repr(self.comment)})'
+
+class LiteralFitsConstraint(ConstraintBase):
+    """
+    A literal value fits a given type
+    """
+    __slots__ = ('type3', 'literal', )
+
+    type3: types.Type3OrPlaceholder
+    literal: Union[ourlang.ConstantPrimitive, ourlang.ConstantTuple, ourlang.ConstantStruct]
+
+    def __init__(
+            self,
+            type3: types.Type3OrPlaceholder,
+            literal: Union[ourlang.ConstantPrimitive, ourlang.ConstantTuple, ourlang.ConstantStruct],
+            comment: Optional[str] = None,
+        ) -> None:
+        super().__init__(comment=comment)
+
+        self.type3 = type3
+        self.literal = literal
+
+    def check(self) -> CheckResult:
+        int_table: Dict[str, Tuple[int, bool]] = {
+            'u8': (1, False),
+            'u32': (4, False),
+            'u64': (8, False),
+            'i8': (1, True),
+            'i32': (4, True),
+            'i64': (8, True),
+        }
+
+        float_table: Dict[str, None] = {
+            'f32': None,
+            'f64': None,
+        }
+
+        if isinstance(self.type3, types.PlaceholderForType):
+            if self.type3.resolve_as is None:
+                return RequireTypeSubstitutes()
+
+            self.type3 = self.type3.resolve_as
+
+        if self.type3.name in int_table:
+            bts, sgn = int_table[self.type3.name]
+
+            if isinstance(self.literal.value, int):
+                try:
+                    self.literal.value.to_bytes(bts, 'big', signed=sgn)
+                except OverflowError:
+                    return Error(f'Must fit in {bts} byte(s)') # FIXME: Add line information
+
+                return None
+
+            return Error('Must be integer') # FIXME: Add line information
+
+        if self.type3.name in float_table:
+            _ = float_table[self.type3.name]
+
+            if isinstance(self.literal.value, float):
+                # FIXME: Bit check
+
+                return None
+
+            return Error('Must be real') # FIXME: Add line information
+
+        res: NewConstraintList
+
+        if isinstance(self.type3, types.AppliedType3):
+            if self.type3.base == types.tuple:
+                if not isinstance(self.literal, ourlang.ConstantTuple):
+                    return Error('Must be tuple')
+
+                if len(self.type3.args) != len(self.literal.value):
+                    return Error('Tuple element count mismatch')
+
+                res = []
+
+                res.extend(
+                    LiteralFitsConstraint(x, y)
+                    for x, y in zip(self.type3.args, self.literal.value)
+                )
+                res.extend(
+                    SameTypeConstraint(x, y.type3)
+                    for x, y in zip(self.type3.args, self.literal.value)
+                )
+
+                return res
+
+            if self.type3.base == types.static_array:
+                if not isinstance(self.literal, ourlang.ConstantTuple):
+                    return Error('Must be tuple')
+
+                assert 2 == len(self.type3.args)
+                assert isinstance(self.type3.args[1], types.IntType3)
+
+                if self.type3.args[1].value != len(self.literal.value):
+                    return Error('Member count mismatch')
+
+                res = []
+
+                res.extend(
+                    LiteralFitsConstraint(self.type3.args[0], y)
+                    for y in self.literal.value
+                )
+                res.extend(
+                    SameTypeConstraint(self.type3.args[0], y.type3)
+                    for y in self.literal.value
+                )
+
+                return res
+
+        if isinstance(self.type3, types.StructType3):
+            if not isinstance(self.literal, ourlang.ConstantStruct):
+                return Error('Must be struct')
+
+            if self.literal.struct_name != self.type3.name:
+                return Error('Struct mismatch')
+
+
+            if len(self.type3.members) != len(self.literal.value):
+                return Error('Struct element count mismatch')
+
+            res = []
+
+            res.extend(
+                LiteralFitsConstraint(x, y)
+                for x, y in zip(self.type3.members.values(), self.literal.value)
+            )
+            res.extend(
+                SameTypeConstraint(x_t, y.type3, comment=f'{self.literal.struct_name}.{x_n}')
+                for (x_n, x_t, ), y in zip(self.type3.members.items(), self.literal.value)
+            )
+
+            return res
+
+        raise NotImplementedError(self.type3, self.literal)
+
+    def human_readable(self) -> HumanReadableRet:
+        return (
+            '{literal} : {type3}',
+            {
+                'literal': self.literal,
+                'type3': self.type3,
+            },
+        )
+
+    def __repr__(self) -> str:
+        return f'LiteralFitsConstraint({repr(self.type3)}, {repr(self.literal)}, comment={repr(self.comment)})'
+
+class CanBeSubscriptedConstraint(ConstraintBase):
+    """
+    A value that is subscipted, i.e. a[0] (tuple) or a[b] (static array)
+    """
+    __slots__ = ('ret_type3', 'type3', 'index', 'index_type3', )
+
+    ret_type3: types.Type3OrPlaceholder
+    type3: types.Type3OrPlaceholder
+    index: ourlang.Expression
+    index_type3: types.Type3OrPlaceholder
+
+    def __init__(self, ret_type3: types.Type3OrPlaceholder, type3: types.Type3OrPlaceholder, index: ourlang.Expression, comment: Optional[str] = None) -> None:
+        super().__init__(comment=comment)
+
+        self.ret_type3 = ret_type3
+        self.type3 = type3
+        self.index = index
+        self.index_type3 = index.type3
+
+    def check(self) -> CheckResult:
+        if isinstance(self.type3, types.PlaceholderForType):
+            if self.type3.resolve_as is None:
+                return RequireTypeSubstitutes()
+
+            self.type3 = self.type3.resolve_as
+
+        if isinstance(self.type3, types.AppliedType3):
+            if self.type3.base == types.static_array:
+                result: List[ConstraintBase] = [
+                    SameTypeConstraint(types.u32, self.index_type3, comment='([]) :: Subscriptable a => a b -> u32 -> b'),
+                    SameTypeConstraint(self.type3.args[0], self.ret_type3, comment='([]) :: Subscriptable a => a b -> u32 -> b'),
+                ]
+
+                if isinstance(self.index, ourlang.ConstantPrimitive):
+                    assert isinstance(self.index.value, int)
+                    assert isinstance(self.type3.args[1], types.IntType3)
+
+                    result.append(
+                        IntegerCompareConstraint(
+                            types.IntType3(0), types.IntType3(self.index.value), types.IntType3(self.type3.args[1].value - 1),
+                            comment='Subscript static array must fit the size of the array'
+                        )
+                    )
+
+                return result
+
+            if self.type3.base == types.tuple:
+                if not isinstance(self.index, ourlang.ConstantPrimitive):
+                    return Error('Must index with literal')
+
+                if not isinstance(self.index.value, int):
+                    return Error('Must index with integer literal')
+
+                if self.index.value < 0 or len(self.type3.args) <= self.index.value:
+                    return Error('Tuple index out of range')
+
+                return [
+                    SameTypeConstraint(types.u32, self.index_type3, comment=f'Tuple subscript index {self.index.value}'),
+                    SameTypeConstraint(self.type3.args[self.index.value], self.ret_type3, comment=f'Tuple subscript index {self.index.value}'),
+                ]
+
+        if self.type3 is types.bytes:
+            return [
+                SameTypeConstraint(types.u32, self.index_type3, comment='([]) :: bytes -> u32 -> u8'),
+                SameTypeConstraint(types.u8, self.ret_type3, comment='([]) :: bytes -> u32 -> u8'),
+            ]
+
+        if self.type3.name in types.LOOKUP_TABLE:
+            return Error(f'{self.type3.name} cannot be subscripted')
+
+        raise NotImplementedError(self.type3)
+
+    def human_readable(self) -> HumanReadableRet:
+        return (
+            '{type3}[{index}]',
+            {
+                'type3': self.type3,
+                'index': self.index,
+            },
+        )
+
+    def __repr__(self) -> str:
+        return f'CanBeSubscriptedConstraint({repr(self.type3)}, {repr(self.index)}, comment={repr(self.comment)})'
diff --git a/phasm/type3/constraintsgenerator.py b/phasm/type3/constraintsgenerator.py
new file mode 100644
index 0000000..61e7ec9
--- /dev/null
+++ b/phasm/type3/constraintsgenerator.py
@@ -0,0 +1,219 @@
+"""
+This module generates the typing constraints for Phasm.
+
+The constraints solver can then try to resolve all constraints.
+"""
+from typing import Generator, List
+
+from .. import ourlang
+
+from .constraints import (
+    Context,
+
+    ConstraintBase,
+    CastableConstraint, CanBeSubscriptedConstraint,
+    LiteralFitsConstraint, MustImplementTypeClassConstraint, SameTypeConstraint,
+)
+
+from . import types as type3types
+
+ConstraintGenerator = Generator[ConstraintBase, None, None]
+
+def phasm_type3_generate_constraints(inp: ourlang.Module) -> List[ConstraintBase]:
+    ctx = Context()
+
+    return [*module(ctx, inp)]
+
+def constant(ctx: Context, inp: ourlang.Constant) -> ConstraintGenerator:
+    if isinstance(inp, (ourlang.ConstantPrimitive, ourlang.ConstantTuple, ourlang.ConstantStruct)):
+        yield LiteralFitsConstraint(inp.type3, inp)
+        return
+
+    raise NotImplementedError(constant, inp)
+
+def expression(ctx: Context, inp: ourlang.Expression) -> ConstraintGenerator:
+    if isinstance(inp, ourlang.Constant):
+        yield from constant(ctx, inp)
+        return
+
+    if isinstance(inp, ourlang.VariableReference):
+        yield SameTypeConstraint(inp.variable.type3, inp.type3,
+            comment=f'typeOf("{inp.variable.name}") == typeOf({inp.variable.name})')
+        return
+
+    if isinstance(inp, ourlang.UnaryOp):
+        if 'len' == inp.operator:
+            yield from expression(ctx, inp.right)
+            yield MustImplementTypeClassConstraint('Sized', inp.right.type3)
+            yield SameTypeConstraint(type3types.u32, inp.type3, comment='len :: Sized a => a -> u32')
+            return
+
+        if 'sqrt' == inp.operator:
+            yield from expression(ctx, inp.right)
+            yield MustImplementTypeClassConstraint('FloatingPoint', inp.right.type3)
+            yield SameTypeConstraint(inp.right.type3, inp.type3, comment='sqrt :: FloatingPoint a => a -> a')
+            return
+
+        if 'cast' == inp.operator:
+            yield from expression(ctx, inp.right)
+            yield CastableConstraint(inp.right.type3, inp.type3)
+            return
+
+        raise NotImplementedError(expression, inp, inp.operator)
+
+    if isinstance(inp, ourlang.BinaryOp):
+        if inp.operator in ('|', '&', '^', ):
+            yield from expression(ctx, inp.left)
+            yield from expression(ctx, inp.right)
+
+            yield MustImplementTypeClassConstraint('BitWiseOperation', inp.left.type3)
+            yield SameTypeConstraint(inp.left.type3, inp.right.type3, inp.type3,
+                comment=f'({inp.operator}) :: a -> a -> a')
+            return
+
+        if inp.operator in ('>>', '<<', ):
+            yield from expression(ctx, inp.left)
+            yield from expression(ctx, inp.right)
+
+            yield MustImplementTypeClassConstraint('BitWiseOperation', inp.left.type3)
+            yield SameTypeConstraint(inp.left.type3, inp.right.type3, inp.type3,
+                comment=f'({inp.operator}) :: a -> a -> a')
+            return
+
+        if inp.operator in ('+', '-', '*', '/', ):
+            yield from expression(ctx, inp.left)
+            yield from expression(ctx, inp.right)
+
+            yield MustImplementTypeClassConstraint('BasicMathOperation', inp.left.type3)
+            yield SameTypeConstraint(inp.left.type3, inp.right.type3, inp.type3,
+                comment=f'({inp.operator}) :: a -> a -> a')
+            return
+
+        if inp.operator == '==':
+            yield from expression(ctx, inp.left)
+            yield from expression(ctx, inp.right)
+
+            yield MustImplementTypeClassConstraint('EqualComparison', inp.left.type3)
+            yield SameTypeConstraint(inp.left.type3, inp.right.type3,
+                comment=f'({inp.operator}) :: a -> a -> bool')
+            yield SameTypeConstraint(inp.type3, type3types.bool_,
+                comment=f'({inp.operator}) :: a -> a -> bool')
+            return
+
+        if inp.operator in ('<', '>'):
+            yield from expression(ctx, inp.left)
+            yield from expression(ctx, inp.right)
+
+            yield MustImplementTypeClassConstraint('StrictPartialOrder', inp.left.type3)
+            yield SameTypeConstraint(inp.left.type3, inp.right.type3,
+                comment=f'({inp.operator}) :: a -> a -> bool')
+            yield SameTypeConstraint(inp.type3, type3types.bool_,
+                comment=f'({inp.operator}) :: a -> a -> bool')
+            return
+
+        raise NotImplementedError(expression, inp)
+
+    if isinstance(inp, ourlang.FunctionCall):
+        yield SameTypeConstraint(inp.function.returns_type3, inp.type3,
+            comment=f'The type of a function call to {inp.function.name} is the same as the type that the function returns')
+
+        assert len(inp.arguments) == len(inp.function.posonlyargs) # FIXME: Make this a Constraint
+
+        for fun_arg, call_arg in zip(inp.function.posonlyargs, inp.arguments):
+            yield from expression(ctx, call_arg)
+            yield SameTypeConstraint(fun_arg.type3, call_arg.type3,
+                comment=f'The type of the value passed to argument {fun_arg.name} of function {inp.function.name} should match the type of that argument')
+
+        return
+
+    if isinstance(inp, ourlang.TupleInstantiation):
+        r_type = []
+        for arg in inp.elements:
+            yield from expression(ctx, arg)
+            r_type.append(arg.type3)
+
+        yield SameTypeConstraint(
+            inp.type3,
+            type3types.AppliedType3(type3types.tuple, r_type),
+            comment=f'The type of a tuple is a combination of its members'
+        )
+
+        return
+
+    if isinstance(inp, ourlang.Subscript):
+        yield from expression(ctx, inp.varref)
+        yield from expression(ctx, inp.index)
+
+        yield CanBeSubscriptedConstraint(inp.type3, inp.varref.type3, inp.index)
+        return
+
+    if isinstance(inp, ourlang.AccessStructMember):
+        yield from expression(ctx, inp.varref)
+        yield SameTypeConstraint(inp.struct_type3.members[inp.member], inp.type3,
+            comment=f'The type of a struct member reference is the same as the type of struct member {inp.struct_type3.name}.{inp.member}')
+        return
+
+    if isinstance(inp, ourlang.Fold):
+        yield from expression(ctx, inp.base)
+        yield from expression(ctx, inp.iter)
+
+        yield SameTypeConstraint(inp.func.posonlyargs[0].type3, inp.func.returns_type3, inp.base.type3, inp.type3,
+            comment='foldl :: Foldable t => (b -> a -> b) -> b -> t a -> b')
+        yield MustImplementTypeClassConstraint('Foldable', inp.iter.type3)
+
+        return
+
+    raise NotImplementedError(expression, inp)
+
+def statement_return(ctx: Context, fun: ourlang.Function, inp: ourlang.StatementReturn) -> ConstraintGenerator:
+    yield from expression(ctx, inp.value)
+
+    yield SameTypeConstraint(fun.returns_type3, inp.value.type3,
+        comment=f'The type of the value returned from function {fun.name} should match its return type')
+
+def statement_if(ctx: Context, fun: ourlang.Function, inp: ourlang.StatementIf) -> ConstraintGenerator:
+    yield from expression(ctx, inp.test)
+
+    yield SameTypeConstraint(inp.test.type3, type3types.bool_,
+        comment=f'Must pass a boolean expression to if')
+
+    for stmt in inp.statements:
+        yield from statement(ctx, fun, stmt)
+
+    for stmt in inp.else_statements:
+        yield from statement(ctx, fun, stmt)
+
+def statement(ctx: Context, fun: ourlang.Function, inp: ourlang.Statement) -> ConstraintGenerator:
+    if isinstance(inp, ourlang.StatementReturn):
+        yield from statement_return(ctx, fun, inp)
+        return
+
+    if isinstance(inp, ourlang.StatementIf):
+        yield from statement_if(ctx, fun, inp)
+        return
+
+    raise NotImplementedError(statement, fun, inp)
+
+def function(ctx: Context, inp: ourlang.Function) -> ConstraintGenerator:
+    assert not inp.imported
+
+    if isinstance(inp, ourlang.StructConstructor):
+        return
+
+    for stmt in inp.statements:
+        yield from statement(ctx, inp, stmt)
+
+def module_constant_def(ctx: Context, inp: ourlang.ModuleConstantDef) -> ConstraintGenerator:
+    yield from constant(ctx, inp.constant)
+    yield SameTypeConstraint(inp.type3, inp.constant.type3,
+        comment=f'The type of the value for module constant definition {inp.name} should match the type of that constant')
+
+def module(ctx: Context, inp: ourlang.Module) -> ConstraintGenerator:
+    for cdef in inp.constant_defs.values():
+        yield from module_constant_def(ctx, cdef)
+
+    for func in inp.functions.values():
+        if func.imported:
+            continue
+
+        yield from function(ctx, func)
diff --git a/phasm/type3/entry.py b/phasm/type3/entry.py
new file mode 100644
index 0000000..c054077
--- /dev/null
+++ b/phasm/type3/entry.py
@@ -0,0 +1,154 @@
+"""
+Entry point to the type3 system
+"""
+from typing import Any, Dict, List, Set
+
+from .. import codestyle
+from .. import ourlang
+
+from .constraints import ConstraintBase, Error, RequireTypeSubstitutes, SameTypeConstraint, SubstitutionMap
+from .constraintsgenerator import phasm_type3_generate_constraints
+from .types import AppliedType3, IntType3, PlaceholderForType, PrimitiveType3, StructType3, Type3, Type3OrPlaceholder
+
+MAX_RESTACK_COUNT = 100
+
+class Type3Exception(BaseException):
+    """
+    Thrown when the Type3 system detects constraints that do not hold
+    """
+
+def phasm_type3(inp: ourlang.Module, verbose: bool = False) -> None:
+    constraint_list = phasm_type3_generate_constraints(inp)
+    assert constraint_list
+
+    placeholder_substitutes: Dict[PlaceholderForType, Type3] = {}
+    placeholder_id_map: Dict[int, str] = {}
+
+    error_list: List[Error] = []
+    for _ in range(MAX_RESTACK_COUNT):
+        if verbose:
+            print()
+            print_constraint_list(placeholder_id_map, constraint_list, placeholder_substitutes)
+
+        old_constraint_ids = {id(x) for x in constraint_list}
+        old_placeholder_substitutes_len = len(placeholder_substitutes)
+
+        new_constraint_list = []
+        for constraint in constraint_list:
+            check_result = constraint.check()
+            if check_result is None:
+                if verbose:
+                    print_constraint(placeholder_id_map, constraint)
+                    print('-> Constraint checks out')
+                continue
+
+            if isinstance(check_result, dict):
+                placeholder_substitutes.update(check_result)
+
+                if verbose:
+                    print_constraint(placeholder_id_map, constraint)
+                    print('-> Constraint checks out, and gave us new information')
+                continue
+
+            if isinstance(check_result, Error):
+                error_list.append(check_result)
+                if verbose:
+                    print_constraint(placeholder_id_map, constraint)
+                    print('-> Got an error')
+                continue
+
+            if isinstance(check_result, RequireTypeSubstitutes):
+                new_constraint_list.append(constraint)
+
+                if verbose:
+                    print_constraint(placeholder_id_map, constraint)
+                    print('-> Back on the todo list')
+                continue
+
+            if isinstance(check_result, list):
+                new_constraint_list.extend(check_result)
+
+                if verbose:
+                    print_constraint(placeholder_id_map, constraint)
+                    print(f'-> Resulted in {len(check_result)} new constraints')
+                continue
+
+            raise NotImplementedError(constraint, check_result)
+
+        if not new_constraint_list:
+            constraint_list = new_constraint_list
+            break
+
+        # Infinite loop detection
+        new_constraint_ids = {id(x) for x in new_constraint_list}
+        new_placeholder_substitutes_len = len(placeholder_substitutes)
+
+        if old_constraint_ids == new_constraint_ids and old_placeholder_substitutes_len == new_placeholder_substitutes_len:
+            if error_list:
+                raise Type3Exception(error_list)
+
+            raise Exception('Cannot type this program - not enough information')
+
+        constraint_list = new_constraint_list
+
+    if constraint_list:
+        raise Exception(f'Cannot type this program - tried {MAX_RESTACK_COUNT} iterations')
+
+    if error_list:
+        raise Type3Exception(error_list)
+
+    # FIXME: This doesn't work with e.g. `:: [a] -> a`, as the placeholder is inside a type
+    for plh, typ in placeholder_substitutes.items():
+        for expr in plh.update_on_substitution:
+            assert expr.type3 is plh
+
+            expr.type3 = typ
+
+def print_constraint(placeholder_id_map: Dict[int, str], constraint: ConstraintBase) -> None:
+    txt, fmt = constraint.human_readable()
+    act_fmt: Dict[str, str] = {}
+    for fmt_key, fmt_val in fmt.items():
+        if isinstance(fmt_val, ourlang.Expression):
+            fmt_val = codestyle.expression(fmt_val)
+
+        if isinstance(fmt_val, Type3) or isinstance(fmt_val, PlaceholderForType):
+            fmt_val = get_printable_type_name(fmt_val, placeholder_id_map)
+
+        if not isinstance(fmt_val, str):
+            fmt_val = repr(fmt_val)
+
+        act_fmt[fmt_key] = fmt_val
+
+    if constraint.comment is not None:
+        print('- ' + txt.format(**act_fmt).ljust(40) + '; ' + constraint.comment)
+    else:
+        print('- ' + txt.format(**act_fmt))
+
+def get_printable_type_name(inp: Type3OrPlaceholder, placeholder_id_map: Dict[int, str]) -> str:
+    if isinstance(inp, (PrimitiveType3, StructType3, IntType3, )):
+        return inp.name
+
+    if isinstance(inp, PlaceholderForType):
+        placeholder_id = id(inp)
+        if placeholder_id not in placeholder_id_map:
+            placeholder_id_map[placeholder_id] = 'T' + str(len(placeholder_id_map) + 1)
+        return placeholder_id_map[placeholder_id]
+
+    if isinstance(inp, AppliedType3):
+        return (
+            get_printable_type_name(inp.base, placeholder_id_map)
+            + ' ('
+            + ') ('.join(get_printable_type_name(x, placeholder_id_map) for x in inp.args)
+            + ')'
+        )
+
+    raise NotImplementedError(inp)
+
+def print_constraint_list(placeholder_id_map: Dict[int, str], constraint_list: List[ConstraintBase], placeholder_substitutes: SubstitutionMap) -> None:
+    print('=== v type3 constraint_list v === ')
+    for psk, psv in placeholder_substitutes.items():
+        print_constraint(placeholder_id_map, SameTypeConstraint(psk, psv, comment='Deduced type'))
+
+    for constraint in constraint_list:
+        print_constraint(placeholder_id_map, constraint)
+    print('=== ^ type3 constraint_list ^ === ')
diff --git a/phasm/type3/types.py b/phasm/type3/types.py
new file mode 100644
index 0000000..bd10abf
--- /dev/null
+++ b/phasm/type3/types.py
@@ -0,0 +1,322 @@
+"""
+Contains the final types for use in Phasm
+
+These are actual, instantiated types; not the abstract types that the
+constraint generator works with.
+"""
+from typing import Any, Dict, Iterable, List, Optional, Protocol, Union
+
+TYPE3_ASSERTION_ERROR = 'You must call phasm_type3 after calling phasm_parse before you can call any other method'
+
+class ExpressionProtocol(Protocol):
+    """
+    A protocol for classes that should be updated on substitution
+    """
+
+    type3: 'Type3OrPlaceholder'
+    """
+    The type to update
+    """
+
+class Type3:
+    """
+    Base class for the type3 types
+    """
+    __slots__ = ('name', )
+
+    name: str
+    """
+    The name of the string, as parsed and outputted by codestyle.
+    """
+
+    def __init__(self, name: str) -> None:
+        self.name = name
+
+    def __repr__(self) -> str:
+        return f'Type3("{self.name}")'
+
+    def __str__(self) -> str:
+        return self.name
+
+    def __format__(self, format_spec: str) -> str:
+        if format_spec != 's':
+            raise TypeError(f'unsupported format string passed to Type3.__format__: {format_spec}')
+
+        return str(self)
+
+    def __eq__(self, other: Any) -> bool:
+        if isinstance(other, PlaceholderForType):
+            return False
+
+        if not isinstance(other, Type3):
+            raise NotImplementedError
+
+        return self is other
+
+    def __ne__(self, other: Any) -> bool:
+        return not self.__eq__(other)
+
+    def __hash__(self) -> int:
+        raise NotImplementedError
+
+    def __bool__(self) -> bool:
+        raise NotImplementedError
+
+class PrimitiveType3(Type3):
+    """
+    Intermediate class to tell primitive types from others
+    """
+
+    __slots__ = ()
+
+class IntType3(Type3):
+    """
+    Sometimes you can have an int as type, e.g. when using static arrays
+    """
+
+    __slots__ = ('value', )
+
+    value: int
+
+    def __init__(self, value: int) -> None:
+        super().__init__(str(value))
+
+        assert 0 <= value
+        self.value = value
+
+    def __eq__(self, other: Any) -> bool:
+        if isinstance(other, IntType3):
+            return self.value == other.value
+
+        if isinstance(other, Type3):
+            return False
+
+        raise NotImplementedError
+
+class PlaceholderForType:
+    """
+    A placeholder type, for when we don't know the final type yet
+    """
+    __slots__ = ('update_on_substitution', 'resolve_as', )
+
+    update_on_substitution: List[ExpressionProtocol]
+    resolve_as: Optional[Type3]
+
+    def __init__(self, update_on_substitution: Iterable[ExpressionProtocol]) -> None:
+        self.update_on_substitution = [*update_on_substitution]
+        self.resolve_as = None
+
+    def __repr__(self) -> str:
+        uos = ', '.join(repr(x) for x in self.update_on_substitution)
+
+        return f'PlaceholderForType({id(self)}, [{uos}])'
+
+    def __str__(self) -> str:
+        return f'PhFT_{id(self)}'
+
+    def __format__(self, format_spec: str) -> str:
+        if format_spec != 's':
+            raise TypeError('unsupported format string passed to Type3.__format__')
+
+        return str(self)
+
+    def __eq__(self, other: Any) -> bool:
+        if isinstance(other, Type3):
+            return False
+
+        if not isinstance(other, PlaceholderForType):
+            raise NotImplementedError
+
+        return self is other
+
+    def __ne__(self, other: Any) -> bool:
+        return not self.__eq__(other)
+
+    def __hash__(self) -> int:
+        return 0 # Valid but performs badly
+
+    def __bool__(self) -> bool:
+        raise NotImplementedError
+
+Type3OrPlaceholder = Union[Type3, PlaceholderForType]
+
+class AppliedType3(Type3):
+    """
+    A Type3 that has been applied to another type
+    """
+    __slots__ = ('base', 'args', )
+
+    base: PrimitiveType3
+    """
+    The base type
+    """
+
+    args: List[Type3OrPlaceholder]
+    """
+    The applied types (or placeholders there for)
+    """
+
+    def __init__(self, base: PrimitiveType3, args: Iterable[Type3OrPlaceholder]) -> None:
+        args = [*args]
+        assert args, 'Must at least one argument'
+
+        super().__init__(
+            base.name
+            + ' ('
+            + ') ('.join(str(x) for x in args) # FIXME: Do we need to redo the name on substitution?
+            + ')'
+        )
+
+        self.base = base
+        self.args = args
+
+    @property
+    def has_placeholders(self) -> bool:
+        return any(
+            isinstance(x, PlaceholderForType)
+            for x in self.args
+        )
+
+    def __eq__(self, other: Any) -> bool:
+        if not isinstance(other, Type3):
+            raise NotImplementedError
+
+        if not isinstance(other, AppliedType3):
+            return False
+
+        return (
+            self.base == other.base
+            and len(self.args) == len(other.args)
+            and all(
+                s == x
+                for s, x in zip(self.args, other.args)
+            )
+        )
+
+    def __repr__(self) -> str:
+        return f'AppliedType3({repr(self.base)}, {repr(self.args)})'
+
+class StructType3(Type3):
+    """
+    A Type3 struct with named members
+    """
+    __slots__ = ('name', 'members', )
+
+    name: str
+    """
+    The structs fully qualified name
+    """
+
+    members: Dict[str, Type3]
+    """
+    The struct's field definitions
+    """
+
+    def __init__(self, name: str, members: Dict[str, Type3]) -> None:
+        super().__init__(name)
+
+        self.name = name
+        self.members = dict(members)
+
+    def __repr__(self) -> str:
+        return f'StructType3(repr({self.name}), repr({self.members}))'
+
+none = PrimitiveType3('none')
+"""
+The none type, for when functions simply don't return anything. e.g., IO().
+"""
+
+bool_ = PrimitiveType3('bool')
+"""
+The bool type, either True or False
+"""
+
+u8 = PrimitiveType3('u8')
+"""
+The unsigned 8-bit integer type.
+
+Operations on variables employ modular arithmetic, with modulus 2^8.
+"""
+
+u32 = PrimitiveType3('u32')
+"""
+The unsigned 32-bit integer type.
+
+Operations on variables employ modular arithmetic, with modulus 2^32.
+"""
+
+u64 = PrimitiveType3('u64')
+"""
+The unsigned 64-bit integer type.
+
+Operations on variables employ modular arithmetic, with modulus 2^64.
+"""
+
+i8 = PrimitiveType3('i8')
+"""
+The signed 8-bit integer type.
+
+Operations on variables employ modular arithmetic, with modulus 2^8, but
+with the middel point being 0.
+"""
+
+i32 = PrimitiveType3('i32')
+"""
+The unsigned 32-bit integer type.
+
+Operations on variables employ modular arithmetic, with modulus 2^32, but
+with the middel point being 0.
+"""
+
+i64 = PrimitiveType3('i64')
+"""
+The unsigned 64-bit integer type.
+
+Operations on variables employ modular arithmetic, with modulus 2^64, but
+with the middel point being 0.
+"""
+
+f32 = PrimitiveType3('f32')
+"""
+A 32-bits IEEE 754 float, of 32 bits width.
+"""
+
+f64 = PrimitiveType3('f64')
+"""
+A 32-bits IEEE 754 float, of 64 bits width.
+"""
+
+bytes = PrimitiveType3('bytes')
+"""
+This is a runtime-determined length piece of memory that can be indexed at runtime.
+"""
+
+static_array = PrimitiveType3('static_array')
+"""
+This is a fixed length piece of memory that can be indexed at runtime.
+
+It should be applied with one argument. It has a runtime-dynamic length
+of the same type repeated.
+"""
+
+tuple = PrimitiveType3('tuple') # pylint: disable=W0622
+"""
+This is a fixed length piece of memory.
+
+It should be applied with zero or more arguments. It has a compile time
+determined length, and each argument can be different.
+"""
+
+LOOKUP_TABLE: Dict[str, Type3] = {
+    'none': none,
+    'bool': bool_,
+    'u8': u8,
+    'u32': u32,
+    'u64': u64,
+    'i8': i8,
+    'i32': i32,
+    'i64': i64,
+    'f32': f32,
+    'f64': f64,
+    'bytes': bytes,
+}
diff --git a/phasm/typing.py b/phasm/typing.py
deleted file mode 100644
index e56f7a9..0000000
--- a/phasm/typing.py
+++ /dev/null
@@ -1,202 +0,0 @@
-"""
-The phasm type system
-"""
-from typing import Optional, List
-
-class TypeBase:
-    """
-    TypeBase base class
-    """
-    __slots__ = ()
-
-    def alloc_size(self) -> int:
-        """
-        When allocating this type in memory, how many bytes do we need to reserve?
-        """
-        raise NotImplementedError(self, 'alloc_size')
-
-class TypeNone(TypeBase):
-    """
-    The None (or Void) type
-    """
-    __slots__ = ()
-
-class TypeBool(TypeBase):
-    """
-    The boolean type
-    """
-    __slots__ = ()
-
-class TypeUInt8(TypeBase):
-    """
-    The Integer type, unsigned and 8 bits wide
-
-    Note that under the hood we need to use i32 to represent
-    these values in expressions. So we need to add some operations
-    to make sure the math checks out.
-
-    So while this does save bytes in memory, it may not actually
-    speed up or improve your code.
-    """
-    __slots__ = ()
-
-    def alloc_size(self) -> int:
-        return 4 # Int32 under the hood
-
-class TypeUInt32(TypeBase):
-    """
-    The Integer type, unsigned and 32 bits wide
-    """
-    __slots__ = ()
-
-    def alloc_size(self) -> int:
-        return 4
-
-class TypeUInt64(TypeBase):
-    """
-    The Integer type, unsigned and 64 bits wide
-    """
-    __slots__ = ()
-
-    def alloc_size(self) -> int:
-        return 8
-
-class TypeInt32(TypeBase):
-    """
-    The Integer type, signed and 32 bits wide
-    """
-    __slots__ = ()
-
-    def alloc_size(self) -> int:
-        return 4
-
-class TypeInt64(TypeBase):
-    """
-    The Integer type, signed and 64 bits wide
-    """
-    __slots__ = ()
-
-    def alloc_size(self) -> int:
-        return 8
-
-class TypeFloat32(TypeBase):
-    """
-    The Float type, 32 bits wide
-    """
-    __slots__ = ()
-
-    def alloc_size(self) -> int:
-        return 4
-
-class TypeFloat64(TypeBase):
-    """
-    The Float type, 64 bits wide
-    """
-    __slots__ = ()
-
-    def alloc_size(self) -> int:
-        return 8
-
-class TypeBytes(TypeBase):
-    """
-    The bytes type
-    """
-    __slots__ = ()
-
-class TypeTupleMember:
-    """
-    Represents a tuple member
-    """
-    def __init__(self, idx: int, type_: TypeBase, offset: int) -> None:
-        self.idx = idx
-        self.type = type_
-        self.offset = offset
-
-class TypeTuple(TypeBase):
-    """
-    The tuple type
-    """
-    __slots__ = ('members', )
-
-    members: List[TypeTupleMember]
-
-    def __init__(self) -> None:
-        self.members = []
-
-    def render_internal_name(self) -> str:
-        """
-        Generates an internal name for this tuple
-        """
-        mems = '@'.join('?' for x in self.members) # FIXME: Should not be a questionmark
-        assert ' ' not in mems, 'Not implement yet: subtuples'
-        return f'tuple@{mems}'
-
-    def alloc_size(self) -> int:
-        return sum(
-            x.type.alloc_size()
-            for x in self.members
-        )
-
-class TypeStaticArrayMember:
-    """
-    Represents a static array member
-    """
-    def __init__(self, idx: int, offset: int) -> None:
-        self.idx = idx
-        self.offset = offset
-
-class TypeStaticArray(TypeBase):
-    """
-    The static array type
-    """
-    __slots__ = ('member_type', 'members', )
-
-    member_type: TypeBase
-    members: List[TypeStaticArrayMember]
-
-    def __init__(self, member_type: TypeBase) -> None:
-        self.member_type = member_type
-        self.members = []
-
-    def alloc_size(self) -> int:
-        return self.member_type.alloc_size() * len(self.members)
-
-class TypeStructMember:
-    """
-    Represents a struct member
-    """
-    def __init__(self, name: str, type_: TypeBase, offset: int) -> None:
-        self.name = name
-        self.type = type_
-        self.offset = offset
-
-class TypeStruct(TypeBase):
-    """
-    A struct has named properties
-    """
-    __slots__ = ('name', 'lineno', 'members', )
-
-    name: str
-    lineno: int
-    members: List[TypeStructMember]
-
-    def __init__(self, name: str, lineno: int) -> None:
-        self.name = name
-        self.lineno = lineno
-        self.members = []
-
-    def get_member(self, name: str) -> Optional[TypeStructMember]:
-        """
-        Returns a member by name
-        """
-        for mem in self.members:
-            if mem.name == name:
-                return mem
-
-        return None
-
-    def alloc_size(self) -> int:
-        return sum(
-            x.type.alloc_size()
-            for x in self.members
-        )
diff --git a/phasm/wasmeasy.py b/phasm/wasmeasy.py
deleted file mode 100644
index d0cf358..0000000
--- a/phasm/wasmeasy.py
+++ /dev/null
@@ -1,69 +0,0 @@
-"""
-Helper functions to quickly generate WASM code
-"""
-from typing import Any, Dict, List, Optional, Type
-
-import functools
-
-from . import wasm
-
-#pylint: disable=C0103,C0115,C0116,R0201,R0902
-
-class Prefix_inn_fnn:
-    def __init__(self, prefix: str) -> None:
-        self.prefix = prefix
-
-        # 6.5.5. Memory Instructions
-        self.load = functools.partial(wasm.Statement, f'{self.prefix}.load')
-        self.store = functools.partial(wasm.Statement, f'{self.prefix}.store')
-
-        # 6.5.6. Numeric Instructions
-        self.clz = functools.partial(wasm.Statement, f'{self.prefix}.clz')
-        self.ctz = functools.partial(wasm.Statement, f'{self.prefix}.ctz')
-        self.popcnt = functools.partial(wasm.Statement, f'{self.prefix}.popcnt')
-        self.add = functools.partial(wasm.Statement, f'{self.prefix}.add')
-        self.sub = functools.partial(wasm.Statement, f'{self.prefix}.sub')
-        self.mul = functools.partial(wasm.Statement, f'{self.prefix}.mul')
-        self.div_s = functools.partial(wasm.Statement, f'{self.prefix}.div_s')
-        self.div_u = functools.partial(wasm.Statement, f'{self.prefix}.div_u')
-        self.rem_s = functools.partial(wasm.Statement, f'{self.prefix}.rem_s')
-        self.rem_u = functools.partial(wasm.Statement, f'{self.prefix}.rem_u')
-        self.and_ = functools.partial(wasm.Statement, f'{self.prefix}.and')
-        self.or_ = functools.partial(wasm.Statement, f'{self.prefix}.or')
-        self.xor = functools.partial(wasm.Statement, f'{self.prefix}.xor')
-        self.shl = functools.partial(wasm.Statement, f'{self.prefix}.shl')
-        self.shr_s = functools.partial(wasm.Statement, f'{self.prefix}.shr_s')
-        self.shr_u = functools.partial(wasm.Statement, f'{self.prefix}.shr_u')
-        self.rotl = functools.partial(wasm.Statement, f'{self.prefix}.rotl')
-        self.rotr = functools.partial(wasm.Statement, f'{self.prefix}.rotr')
-
-        self.eqz = functools.partial(wasm.Statement, f'{self.prefix}.eqz')
-        self.eq = functools.partial(wasm.Statement, f'{self.prefix}.eq')
-        self.ne = functools.partial(wasm.Statement, f'{self.prefix}.ne')
-        self.lt_s = functools.partial(wasm.Statement, f'{self.prefix}.lt_s')
-        self.lt_u = functools.partial(wasm.Statement, f'{self.prefix}.lt_u')
-        self.gt_s = functools.partial(wasm.Statement, f'{self.prefix}.gt_s')
-        self.gt_u = functools.partial(wasm.Statement, f'{self.prefix}.gt_u')
-        self.le_s = functools.partial(wasm.Statement, f'{self.prefix}.le_s')
-        self.le_u = functools.partial(wasm.Statement, f'{self.prefix}.le_u')
-        self.ge_s = functools.partial(wasm.Statement, f'{self.prefix}.ge_s')
-        self.ge_u = functools.partial(wasm.Statement, f'{self.prefix}.ge_u')
-
-    def const(self, value: int, comment: Optional[str] = None) -> wasm.Statement:
-        return wasm.Statement(f'{self.prefix}.const', f'0x{value:08x}', comment=comment)
-
-i32 = Prefix_inn_fnn('i32')
-i64 = Prefix_inn_fnn('i64')
-
-class Block:
-    def __init__(self, start: str) -> None:
-        self.start = start
-
-    def __call__(self, *statements: wasm.Statement) -> List[wasm.Statement]:
-        return [
-            wasm.Statement('if'),
-            *statements,
-            wasm.Statement('end'),
-        ]
-
-if_ = Block('if')
diff --git a/pylintrc b/pylintrc
index 0591be3..f872f8d 100644
--- a/pylintrc
+++ b/pylintrc
@@ -1,5 +1,5 @@
 [MASTER]
-disable=C0122,R0903,R0911,R0912,R0913,R0915,R1710,W0223
+disable=C0103,C0122,R0902,R0903,R0911,R0912,R0913,R0915,R1710,W0223
 
 max-line-length=180
 
@@ -7,4 +7,4 @@ max-line-length=180
 good-names=g
 
 [tests]
-disable=C0116,
+disable=C0116,R0201
diff --git a/requirements.txt b/requirements.txt
index d29e53c..64dce30 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,10 +1,10 @@
-mypy==0.812
+mypy==0.991
 pygments==2.12.0
-pylint==2.7.4
-pytest==6.2.2
+pylint==2.15.9
+pytest==7.2.0
 pytest-integration==0.2.2
 pywasm==1.0.7
 pywasm3==0.5.0
 wasmer==1.1.0
 wasmer_compiler_cranelift==1.1.0
-wasmtime==0.36.0
+wasmtime==3.0.0
diff --git a/tests/integration/constants.py b/tests/integration/constants.py
new file mode 100644
index 0000000..c2f8860
--- /dev/null
+++ b/tests/integration/constants.py
@@ -0,0 +1,16 @@
+"""
+Constants for use in the tests
+"""
+
+ALL_INT_TYPES = ['u8', 'u32', 'u64', 'i32', 'i64']
+COMPLETE_INT_TYPES = ['u32', 'u64', 'i32', 'i64']
+
+ALL_FLOAT_TYPES = ['f32', 'f64']
+COMPLETE_FLOAT_TYPES = ALL_FLOAT_TYPES
+
+TYPE_MAP = {
+    **{x: int for x in ALL_INT_TYPES},
+    **{x: float for x in ALL_FLOAT_TYPES},
+}
+
+COMPLETE_NUMERIC_TYPES = COMPLETE_INT_TYPES + COMPLETE_FLOAT_TYPES
diff --git a/tests/integration/helpers.py b/tests/integration/helpers.py
index ca4c8a7..3cd682c 100644
--- a/tests/integration/helpers.py
+++ b/tests/integration/helpers.py
@@ -24,7 +24,7 @@ class Suite:
     def __init__(self, code_py):
         self.code_py = code_py
 
-    def run_code(self, *args, runtime='pywasm3', imports=None):
+    def run_code(self, *args, runtime='pywasm3', func_name='testEntry', imports=None):
         """
         Compiles the given python code into wasm and
         then runs it
@@ -74,7 +74,7 @@ class Suite:
         runner.interpreter_dump_memory(sys.stderr)
 
         result = SuiteResult()
-        result.returned_value = runner.call('testEntry', *wasm_args)
+        result.returned_value = runner.call(func_name, *wasm_args)
 
         write_header(sys.stderr, 'Memory (post run)')
         runner.interpreter_dump_memory(sys.stderr)
diff --git a/tests/integration/runners.py b/tests/integration/runners.py
index fd3a53e..91a29fd 100644
--- a/tests/integration/runners.py
+++ b/tests/integration/runners.py
@@ -13,6 +13,7 @@ import wasmtime
 
 from phasm.compiler import phasm_compile
 from phasm.parser import phasm_parse
+from phasm.type3.entry import phasm_type3
 from phasm import ourlang
 from phasm import wasm
 
@@ -40,6 +41,7 @@ class RunnerBase:
         Parses the Phasm code into an AST
         """
         self.phasm_ast = phasm_parse(self.phasm_code)
+        phasm_type3(self.phasm_ast, verbose=True)
 
     def compile_ast(self) -> None:
         """
@@ -160,7 +162,7 @@ class RunnerPywasm3(RunnerBase):
         memory = self.rtime.get_memory(0)
 
         for idx, byt in enumerate(data):
-            memory[offset + idx] = byt # type: ignore
+            memory[offset + idx] = byt
 
     def interpreter_read_memory(self, offset: int, length: int) -> bytes:
         memory = self.rtime.get_memory(0)
diff --git a/tests/integration/test_constants.py b/tests/integration/test_constants.py
deleted file mode 100644
index 19f0203..0000000
--- a/tests/integration/test_constants.py
+++ /dev/null
@@ -1,87 +0,0 @@
-import pytest
-
-from .helpers import Suite
-
-@pytest.mark.integration_test
-def test_i32():
-    code_py = """
-CONSTANT: i32 = 13
-
-@exported
-def testEntry() -> i32:
-    return CONSTANT * 5
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 65 == result.returned_value
-
-@pytest.mark.integration_test
-@pytest.mark.parametrize('type_', ['u8', 'u32', 'u64', ])
-def test_tuple_1(type_):
-    code_py = f"""
-CONSTANT: ({type_}, ) = (65, )
-
-@exported
-def testEntry() -> {type_}:
-    return helper(CONSTANT)
-
-def helper(vector: ({type_}, )) -> {type_}:
-    return vector[0]
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 65 == result.returned_value
-
-@pytest.mark.integration_test
-def test_tuple_6():
-    code_py = """
-CONSTANT: (u8, u8, u32, u32, u64, u64, ) = (11, 22, 3333, 4444, 555555, 666666, )
-
-@exported
-def testEntry() -> u32:
-    return helper(CONSTANT)
-
-def helper(vector: (u8, u8, u32, u32, u64, u64, )) -> u32:
-    return vector[2]
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 3333 == result.returned_value
-
-@pytest.mark.integration_test
-@pytest.mark.parametrize('type_', ['u8', 'u32', 'u64', ])
-def test_static_array_1(type_):
-    code_py = f"""
-CONSTANT: {type_}[1] = (65, )
-
-@exported
-def testEntry() -> {type_}:
-    return helper(CONSTANT)
-
-def helper(vector: {type_}[1]) -> {type_}:
-    return vector[0]
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 65 == result.returned_value
-
-@pytest.mark.integration_test
-def test_static_array_6():
-    code_py = """
-CONSTANT: u32[6] = (11, 22, 3333, 4444, 555555, 666666, )
-
-@exported
-def testEntry() -> u32:
-    return helper(CONSTANT)
-
-def helper(vector: u32[6]) -> u32:
-    return vector[2]
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 3333 == result.returned_value
diff --git a/tests/integration/test_examples/__init__.py b/tests/integration/test_examples/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/integration/test_examples/test_buffer.py b/tests/integration/test_examples/test_buffer.py
new file mode 100644
index 0000000..b987c69
--- /dev/null
+++ b/tests/integration/test_examples/test_buffer.py
@@ -0,0 +1,19 @@
+import pytest
+
+from ..helpers import Suite
+
+@pytest.mark.slow_integration_test
+def test_index():
+    with open('examples/buffer.py', 'r', encoding='ASCII') as fil:
+        code_py = "\n" + fil.read()
+
+    result = Suite(code_py).run_code(b'Hello, world!', 5, func_name='index', runtime='wasmtime')
+    assert 44 == result.returned_value
+
+@pytest.mark.slow_integration_test
+def test_length():
+    with open('examples/buffer.py', 'r', encoding='ASCII') as fil:
+        code_py = "\n" + fil.read()
+
+    result = Suite(code_py).run_code(b'Hello, world!', func_name='length')
+    assert 13 == result.returned_value
diff --git a/tests/integration/test_examples.py b/tests/integration/test_examples/test_crc32.py
similarity index 93%
rename from tests/integration/test_examples.py
rename to tests/integration/test_examples/test_crc32.py
index b3b278d..d9f74bf 100644
--- a/tests/integration/test_examples.py
+++ b/tests/integration/test_examples/test_crc32.py
@@ -3,9 +3,9 @@ import struct
 
 import pytest
 
-from .helpers import Suite
+from ..helpers import Suite
 
-@pytest.mark.integration_test
+@pytest.mark.slow_integration_test
 def test_crc32():
     # FIXME: Stub
     # crc = 0xFFFFFFFF
diff --git a/tests/integration/test_examples/test_fib.py b/tests/integration/test_examples/test_fib.py
new file mode 100644
index 0000000..9474a20
--- /dev/null
+++ b/tests/integration/test_examples/test_fib.py
@@ -0,0 +1,12 @@
+import pytest
+
+from ..helpers import Suite
+
+@pytest.mark.slow_integration_test
+def test_fib():
+    with open('./examples/fib.py', 'r', encoding='UTF-8') as fil:
+        code_py = "\n" + fil.read()
+
+    result = Suite(code_py).run_code()
+
+    assert 102334155 == result.returned_value
diff --git a/tests/integration/test_fib.py b/tests/integration/test_fib.py
deleted file mode 100644
index 20e7e63..0000000
--- a/tests/integration/test_fib.py
+++ /dev/null
@@ -1,30 +0,0 @@
-import pytest
-
-from .helpers import Suite
-
-@pytest.mark.slow_integration_test
-def test_fib():
-    code_py = """
-def helper(n: i32, a: i32, b: i32) -> i32:
-    if n < 1:
-        return a + b
-
-    return helper(n - 1, a + b, a)
-
-def fib(n: i32) -> i32:
-    if n == 0:
-        return 0
-
-    if n == 1:
-        return 1
-
-    return helper(n - 1, 0, 1)
-
-@exported
-def testEntry() -> i32:
-    return fib(40)
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 102334155 == result.returned_value
diff --git a/tests/integration/test_helper.py b/tests/integration/test_helper.py
deleted file mode 100644
index cb44021..0000000
--- a/tests/integration/test_helper.py
+++ /dev/null
@@ -1,70 +0,0 @@
-import io
-
-import pytest
-
-from pywasm import binary
-from pywasm import Runtime
-
-from wasmer import wat2wasm
-
-def run(code_wat):
-    code_wasm = wat2wasm(code_wat)
-    module = binary.Module.from_reader(io.BytesIO(code_wasm))
-
-    runtime = Runtime(module, {}, {})
-
-    out_put = runtime.exec('testEntry', [])
-    return (runtime, out_put)
-
-@pytest.mark.parametrize('size,offset,exp_out_put', [
-    ('32', 0,         0x3020100),
-    ('32', 1,         0x4030201),
-    ('64', 0, 0x706050403020100),
-    ('64', 2, 0x908070605040302),
-])
-def test_i32_64_load(size, offset, exp_out_put):
-    code_wat = f"""
-  (module
-    (memory 1)
-     (data (memory 0) (i32.const 0) "\\00\\01\\02\\03\\04\\05\\06\\07\\08\\09\\10")
-
-    (func (export "testEntry") (result i{size})
-      i32.const {offset}
-      i{size}.load
-      return ))
-"""
-
-    (_, out_put) = run(code_wat)
-    assert exp_out_put == out_put
-
-def test_load_then_store():
-    code_wat = """
-  (module
-    (memory 1)
-    (data (memory 0) (i32.const 0) "\\04\\00\\00\\00")
-
-    (func (export "testEntry") (result i32) (local $my_memory_value i32)
-      ;; Load i32 from address 0
-      i32.const 0
-      i32.load
-
-      ;; Add 8 to the loaded value
-      i32.const 8
-      i32.add
-
-      local.set $my_memory_value
-
-      ;; Store back to the memory
-      i32.const 0
-      local.get $my_memory_value
-      i32.store
-
-      ;; Return something
-      i32.const 9
-      return ))
-"""
-    (runtime, out_put) = run(code_wat)
-
-    assert 9 == out_put
-
-    assert (b'\x0c'+ b'\00' * 23) == runtime.store.mems[0].data[:24]
diff --git a/tests/integration/test_lang/__init__.py b/tests/integration/test_lang/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/integration/test_builtins.py b/tests/integration/test_lang/test_builtins.py
similarity index 95%
rename from tests/integration/test_builtins.py
rename to tests/integration/test_lang/test_builtins.py
index 4b84197..2b06afd 100644
--- a/tests/integration/test_builtins.py
+++ b/tests/integration/test_lang/test_builtins.py
@@ -2,8 +2,8 @@ import sys
 
 import pytest
 
-from .helpers import Suite, write_header
-from .runners import RunnerPywasm
+from ..helpers import Suite, write_header
+from ..runners import RunnerPywasm
 
 def setup_interpreter(phash_code: str) -> RunnerPywasm:
     runner = RunnerPywasm(phash_code)
diff --git a/tests/integration/test_lang/test_bytes.py b/tests/integration/test_lang/test_bytes.py
new file mode 100644
index 0000000..af3f78d
--- /dev/null
+++ b/tests/integration/test_lang/test_bytes.py
@@ -0,0 +1,84 @@
+import pytest
+
+from phasm.type3.entry import Type3Exception
+
+from ..helpers import Suite
+
+@pytest.mark.integration_test
+def test_bytes_address():
+    code_py = """
+@exported
+def testEntry(f: bytes) -> bytes:
+    return f
+"""
+
+    result = Suite(code_py).run_code(b'This is a test')
+
+    # THIS DEPENDS ON THE ALLOCATOR
+    # A different allocator will return a different value
+    assert 20 == result.returned_value
+
+@pytest.mark.integration_test
+def test_bytes_length():
+    code_py = """
+@exported
+def testEntry(f: bytes) -> u32:
+    return len(f)
+"""
+
+    result = Suite(code_py).run_code(b'This yet is another test')
+
+    assert 24 == result.returned_value
+
+@pytest.mark.integration_test
+def test_bytes_index():
+    code_py = """
+@exported
+def testEntry(f: bytes) -> u8:
+    return f[8]
+"""
+
+    result = Suite(code_py).run_code(b'This is another test')
+
+    assert 0x61 == result.returned_value
+
+@pytest.mark.integration_test
+def test_bytes_index_out_of_bounds():
+    code_py = """
+@exported
+def testEntry(f: bytes) -> u8:
+    return f[50]
+"""
+
+    result = Suite(code_py).run_code(b'Short', b'Long' * 100)
+
+    assert 0 == result.returned_value
+
+@pytest.mark.integration_test
+def test_function_call_element_ok():
+    code_py = """
+@exported
+def testEntry(f: bytes) -> u8:
+    return helper(f[0])
+
+def helper(x: u8) -> u8:
+    return x
+"""
+
+    result = Suite(code_py).run_code(b'Short')
+
+    assert 83 == result.returned_value
+
+@pytest.mark.integration_test
+def test_function_call_element_type_mismatch():
+    code_py = """
+@exported
+def testEntry(f: bytes) -> u64:
+    return helper(f[0])
+
+def helper(x: u64) -> u64:
+    return x
+"""
+
+    with pytest.raises(Type3Exception, match=r'u64 must be u8 instead'):
+        Suite(code_py).run_code()
diff --git a/tests/integration/test_lang/test_if.py b/tests/integration/test_lang/test_if.py
new file mode 100644
index 0000000..5d77eb9
--- /dev/null
+++ b/tests/integration/test_lang/test_if.py
@@ -0,0 +1,71 @@
+import pytest
+
+from ..helpers import Suite
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('inp', [9, 10, 11, 12])
+def test_if_simple(inp):
+    code_py = """
+@exported
+def testEntry(a: i32) -> i32:
+    if a > 10:
+        return 15
+
+    return 3
+"""
+    exp_result = 15 if inp > 10 else 3
+
+    suite = Suite(code_py)
+
+    result = suite.run_code(inp)
+    assert exp_result == result.returned_value
+
+@pytest.mark.integration_test
+@pytest.mark.skip('Such a return is not how things should be')
+def test_if_complex():
+    code_py = """
+@exported
+def testEntry(a: i32) -> i32:
+    if a > 10:
+        return 10
+    elif a > 0:
+        return a
+    else:
+        return 0
+
+    return -1 # Required due to function type
+"""
+
+    suite = Suite(code_py)
+
+    assert 10 == suite.run_code(20).returned_value
+    assert 10 == suite.run_code(10).returned_value
+
+    assert 8 == suite.run_code(8).returned_value
+
+    assert 0 == suite.run_code(0).returned_value
+    assert 0 == suite.run_code(-1).returned_value
+
+@pytest.mark.integration_test
+def test_if_nested():
+    code_py = """
+@exported
+def testEntry(a: i32, b: i32) -> i32:
+    if a > 11:
+        if b > 11:
+            return 3
+
+        return 2
+
+    if b > 11:
+        return 1
+
+    return 0
+"""
+
+    suite = Suite(code_py)
+
+    assert 3 == suite.run_code(20, 20).returned_value
+    assert 2 == suite.run_code(20, 10).returned_value
+    assert 1 == suite.run_code(10, 20).returned_value
+    assert 0 == suite.run_code(10, 10).returned_value
diff --git a/tests/integration/test_lang/test_interface.py b/tests/integration/test_lang/test_interface.py
new file mode 100644
index 0000000..a8dfc32
--- /dev/null
+++ b/tests/integration/test_lang/test_interface.py
@@ -0,0 +1,79 @@
+import pytest
+
+from phasm.type3.entry import Type3Exception
+
+from ..helpers import Suite
+
+@pytest.mark.integration_test
+def test_imported_ok():
+    code_py = """
+@imported
+def helper(mul: i32) -> i32:
+    pass
+
+@exported
+def testEntry() -> i32:
+    return helper(2)
+"""
+
+    def helper(mul: int) -> int:
+        return 4238 * mul
+
+    result = Suite(code_py).run_code(
+        runtime='wasmer',
+        imports={
+            'helper': helper,
+        }
+    )
+
+    assert 8476 == result.returned_value
+
+@pytest.mark.integration_test
+def test_imported_side_effect_no_return():
+    code_py = """
+@imported
+def helper(mul: u8) -> None:
+    pass
+
+@exported
+def testEntry() -> None:
+    return helper(3)
+"""
+    prop = None
+
+    def helper(mul: int) -> None:
+        nonlocal prop
+        prop = mul
+
+    result = Suite(code_py).run_code(
+        runtime='wasmer',
+        imports={
+            'helper': helper,
+        }
+    )
+
+    assert None is result.returned_value
+    assert 3 == prop
+
+@pytest.mark.integration_test
+def test_imported_type_mismatch():
+    code_py = """
+@imported
+def helper(mul: u8) -> u8:
+    pass
+
+@exported
+def testEntry(x: u32) -> u8:
+    return helper(x)
+"""
+
+    def helper(mul: int) -> int:
+        return 4238 * mul
+
+    with pytest.raises(Type3Exception, match=r'u32 must be u8 instead'):
+        Suite(code_py).run_code(
+            runtime='wasmer',
+            imports={
+                'helper': helper,
+            }
+        )
diff --git a/tests/integration/test_lang/test_primitives.py b/tests/integration/test_lang/test_primitives.py
new file mode 100644
index 0000000..41a8211
--- /dev/null
+++ b/tests/integration/test_lang/test_primitives.py
@@ -0,0 +1,486 @@
+import pytest
+
+from phasm.type3.entry import Type3Exception
+
+from ..helpers import Suite
+from ..constants import ALL_INT_TYPES, ALL_FLOAT_TYPES, COMPLETE_INT_TYPES, TYPE_MAP
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', ALL_INT_TYPES)
+def test_expr_constant_int(type_):
+    code_py = f"""
+@exported
+def testEntry() -> {type_}:
+    return 13
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 13 == result.returned_value
+    assert TYPE_MAP[type_] == type(result.returned_value)
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', ALL_FLOAT_TYPES)
+def test_expr_constant_float(type_):
+    code_py = f"""
+@exported
+def testEntry() -> {type_}:
+    return 32.125
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 32.125 == result.returned_value
+    assert TYPE_MAP[type_] == type(result.returned_value)
+
+@pytest.mark.integration_test
+def test_expr_constant_literal_does_not_fit():
+    code_py = """
+@exported
+def testEntry() -> u8:
+    return 1000
+"""
+
+    with pytest.raises(Type3Exception, match=r'Must fit in 1 byte\(s\)'):
+        Suite(code_py).run_code()
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', ALL_INT_TYPES)
+def test_module_constant_int(type_):
+    code_py = f"""
+CONSTANT: {type_} = 13
+
+@exported
+def testEntry() -> {type_}:
+    return CONSTANT
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 13 == result.returned_value
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', ALL_FLOAT_TYPES)
+def test_module_constant_float(type_):
+    code_py = f"""
+CONSTANT: {type_} = 32.125
+
+@exported
+def testEntry() -> {type_}:
+    return CONSTANT
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 32.125 == result.returned_value
+
+@pytest.mark.integration_test
+def test_module_constant_type_failure():
+    code_py = """
+CONSTANT: u8 = 1000
+
+@exported
+def testEntry() -> u32:
+    return 14
+"""
+
+    with pytest.raises(Type3Exception, match=r'Must fit in 1 byte\(s\)'):
+        Suite(code_py).run_code()
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', ['u32', 'u64']) # FIXME: Support u8, requires an extra AND operation
+def test_logical_left_shift(type_):
+    code_py = f"""
+@exported
+def testEntry() -> {type_}:
+    return 10 << 3
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 80 == result.returned_value
+    assert TYPE_MAP[type_] == type(result.returned_value)
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', ['u32', 'u64'])
+def test_logical_right_shift_left_bit_zero(type_):
+    code_py = f"""
+@exported
+def testEntry() -> {type_}:
+    return 10 >> 3
+"""
+
+    # Check with wasmtime, as other engines don't mind if the type
+    # doesn't match. They'll complain when: (>>) : u32 -> u64 -> u32
+    result = Suite(code_py).run_code(runtime='wasmtime')
+
+    assert 1 == result.returned_value
+    assert TYPE_MAP[type_] == type(result.returned_value)
+
+@pytest.mark.integration_test
+def test_logical_right_shift_left_bit_one():
+    code_py = """
+@exported
+def testEntry() -> u32:
+    return 4294967295 >> 16
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 0xFFFF == result.returned_value
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', ['u8', 'u32', 'u64'])
+def test_bitwise_or_uint(type_):
+    code_py = f"""
+@exported
+def testEntry() -> {type_}:
+    return 10 | 3
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 11 == result.returned_value
+    assert TYPE_MAP[type_] == type(result.returned_value)
+
+@pytest.mark.integration_test
+def test_bitwise_or_inv_type():
+    code_py = """
+@exported
+def testEntry() -> f64:
+    return 10.0 | 3.0
+"""
+
+    with pytest.raises(Type3Exception, match='f64 does not implement the BitWiseOperation type class'):
+        Suite(code_py).run_code()
+
+@pytest.mark.integration_test
+def test_bitwise_or_type_mismatch():
+    code_py = """
+CONSTANT1: u32 = 3
+CONSTANT2: u64 = 3
+
+@exported
+def testEntry() -> u64:
+    return CONSTANT1 | CONSTANT2
+"""
+
+    with pytest.raises(Type3Exception, match='u64 must be u32 instead'):
+        Suite(code_py).run_code()
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', ['u8', 'u32', 'u64'])
+def test_bitwise_xor(type_):
+    code_py = f"""
+@exported
+def testEntry() -> {type_}:
+    return 10 ^ 3
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 9 == result.returned_value
+    assert TYPE_MAP[type_] == type(result.returned_value)
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', ['u8', 'u32', 'u64'])
+def test_bitwise_and(type_):
+    code_py = f"""
+@exported
+def testEntry() -> {type_}:
+    return 10 & 3
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 2 == result.returned_value
+    assert TYPE_MAP[type_] == type(result.returned_value)
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', COMPLETE_INT_TYPES)
+def test_addition_int(type_):
+    code_py = f"""
+@exported
+def testEntry() -> {type_}:
+    return 10 + 3
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 13 == result.returned_value
+    assert TYPE_MAP[type_] == type(result.returned_value)
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', ALL_FLOAT_TYPES)
+def test_addition_float(type_):
+    code_py = f"""
+@exported
+def testEntry() -> {type_}:
+    return 32.0 + 0.125
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 32.125 == result.returned_value
+    assert TYPE_MAP[type_] == type(result.returned_value)
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', COMPLETE_INT_TYPES)
+def test_subtraction_int(type_):
+    code_py = f"""
+@exported
+def testEntry() -> {type_}:
+    return 10 - 3
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 7 == result.returned_value
+    assert TYPE_MAP[type_] == type(result.returned_value)
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', ALL_FLOAT_TYPES)
+def test_subtraction_float(type_):
+    code_py = f"""
+@exported
+def testEntry() -> {type_}:
+    return 100.0 - 67.875
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 32.125 == result.returned_value
+    assert TYPE_MAP[type_] == type(result.returned_value)
+
+@pytest.mark.integration_test
+@pytest.mark.skip('TODO: Runtimes return a signed value, which is difficult to test')
+@pytest.mark.parametrize('type_', ('u32', 'u64')) # FIXME: u8
+def test_subtraction_underflow(type_):
+    code_py = f"""
+@exported
+def testEntry() -> {type_}:
+    return 10 - 11
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 0 < result.returned_value
+
+# TODO: Multiplication
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', COMPLETE_INT_TYPES)
+def test_division_int(type_):
+    code_py = f"""
+@exported
+def testEntry() -> {type_}:
+    return 10 / 3
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 3 == result.returned_value
+    assert TYPE_MAP[type_] == type(result.returned_value)
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', ALL_FLOAT_TYPES)
+def test_division_float(type_):
+    code_py = f"""
+@exported
+def testEntry() -> {type_}:
+    return 10.0 / 8.0
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 1.25 == result.returned_value
+    assert TYPE_MAP[type_] == type(result.returned_value)
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', COMPLETE_INT_TYPES)
+def test_division_zero_let_it_crash_int(type_):
+    code_py = f"""
+@exported
+def testEntry() -> {type_}:
+    return 10 / 0
+"""
+
+    # WebAssembly dictates that integer division is a partial operator (e.g. unreachable for 0)
+    # https://www.w3.org/TR/wasm-core-1/#-hrefop-idiv-umathrmidiv_u_n-i_1-i_2
+    with pytest.raises(Exception):
+        Suite(code_py).run_code()
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', ALL_FLOAT_TYPES)
+def test_division_zero_let_it_crash_float(type_):
+    code_py = f"""
+@exported
+def testEntry() -> {type_}:
+    return 10.0 / 0.0
+"""
+
+    # WebAssembly dictates that float division follows the IEEE rules
+    # https://www.w3.org/TR/wasm-core-1/#-hrefop-fdivmathrmfdiv_n-z_1-z_2
+    result = Suite(code_py).run_code()
+    assert float('+inf') == result.returned_value
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', ['f32', 'f64'])
+def test_builtins_sqrt(type_):
+    code_py = f"""
+@exported
+def testEntry() -> {type_}:
+    return sqrt(25.0)
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 5 == result.returned_value
+    assert TYPE_MAP[type_] == type(result.returned_value)
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', TYPE_MAP.keys())
+def test_function_argument(type_):
+    code_py = f"""
+@exported
+def testEntry(a: {type_}) -> {type_}:
+    return a
+"""
+
+    result = Suite(code_py).run_code(125)
+
+    assert 125 == result.returned_value
+    assert TYPE_MAP[type_] == type(result.returned_value)
+
+@pytest.mark.integration_test
+@pytest.mark.skip('TODO')
+def test_explicit_positive_number():
+    code_py = """
+@exported
+def testEntry() -> i32:
+    return +523
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 523 == result.returned_value
+
+@pytest.mark.integration_test
+@pytest.mark.skip('TODO')
+def test_explicit_negative_number():
+    code_py = """
+@exported
+def testEntry() -> i32:
+    return -19
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert -19 == result.returned_value
+
+@pytest.mark.integration_test
+def test_call_no_args():
+    code_py = """
+def helper() -> i32:
+    return 19
+
+@exported
+def testEntry() -> i32:
+    return helper()
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 19 == result.returned_value
+
+@pytest.mark.integration_test
+def test_call_pre_defined():
+    code_py = """
+def helper(left: i32) -> i32:
+    return left
+
+@exported
+def testEntry() -> i32:
+    return helper(13)
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 13 == result.returned_value
+
+@pytest.mark.integration_test
+def test_call_post_defined():
+    code_py = """
+@exported
+def testEntry() -> i32:
+    return helper(10, 3)
+
+def helper(left: i32, right: i32) -> i32:
+    return left - right
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 7 == result.returned_value
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', COMPLETE_INT_TYPES)
+def test_call_with_expression_int(type_):
+    code_py = f"""
+@exported
+def testEntry() -> {type_}:
+    return helper(10 + 20, 3 + 5)
+
+def helper(left: {type_}, right: {type_}) -> {type_}:
+    return left - right
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 22 == result.returned_value
+    assert TYPE_MAP[type_] == type(result.returned_value)
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', ALL_FLOAT_TYPES)
+def test_call_with_expression_float(type_):
+    code_py = f"""
+@exported
+def testEntry() -> {type_}:
+    return helper(10.078125 + 90.046875, 63.0 + 5.0)
+
+def helper(left: {type_}, right: {type_}) -> {type_}:
+    return left - right
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 32.125 == result.returned_value
+    assert TYPE_MAP[type_] == type(result.returned_value)
+
+@pytest.mark.integration_test
+def test_call_invalid_return_type():
+    code_py = """
+def helper() -> i64:
+    return 19
+
+@exported
+def testEntry() -> i32:
+    return helper()
+"""
+
+    with pytest.raises(Type3Exception, match=r'i64 must be i32 instead'):
+        Suite(code_py).run_code()
+
+@pytest.mark.integration_test
+def test_call_invalid_arg_type():
+    code_py = """
+def helper(left: u8) -> u8:
+    return left
+
+@exported
+def testEntry() -> u8:
+    return helper(500)
+"""
+
+    with pytest.raises(Type3Exception, match=r'Must fit in 1 byte\(s\)'):
+        Suite(code_py).run_code()
diff --git a/tests/integration/test_lang/test_static_array.py b/tests/integration/test_lang/test_static_array.py
new file mode 100644
index 0000000..4d32cd8
--- /dev/null
+++ b/tests/integration/test_lang/test_static_array.py
@@ -0,0 +1,195 @@
+import pytest
+
+from phasm.type3.entry import Type3Exception
+
+from ..constants import (
+    ALL_FLOAT_TYPES, ALL_INT_TYPES, COMPLETE_INT_TYPES, COMPLETE_NUMERIC_TYPES, TYPE_MAP
+)
+from ..helpers import Suite
+
+@pytest.mark.integration_test
+def test_module_constant_def():
+    code_py = """
+CONSTANT: u8[3] = (24, 57, 80, )
+
+@exported
+def testEntry() -> i32:
+    return 0
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 0 == result.returned_value
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', ALL_INT_TYPES)
+def test_module_constant_3(type_):
+    code_py = f"""
+CONSTANT: {type_}[3] = (24, 57, 80, )
+
+@exported
+def testEntry() -> {type_}:
+    return CONSTANT[1]
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 57 == result.returned_value
+    assert TYPE_MAP[type_] == type(result.returned_value)
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', COMPLETE_INT_TYPES)
+def test_function_call_int(type_):
+    code_py = f"""
+CONSTANT: {type_}[3] = (24, 57, 80, )
+
+@exported
+def testEntry() -> {type_}:
+    return helper(CONSTANT)
+
+def helper(array: {type_}[3]) -> {type_}:
+    return array[0] + array[1] + array[2]
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 161 == result.returned_value
+    assert TYPE_MAP[type_] == type(result.returned_value)
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', ALL_FLOAT_TYPES)
+def test_function_call_float(type_):
+    code_py = f"""
+CONSTANT: {type_}[3] = (24.0, 57.5, 80.75, )
+
+@exported
+def testEntry() -> {type_}:
+    return helper(CONSTANT)
+
+def helper(array: {type_}[3]) -> {type_}:
+    return array[0] + array[1] + array[2]
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 162.25 == result.returned_value
+    assert TYPE_MAP[type_] == type(result.returned_value)
+
+@pytest.mark.integration_test
+def test_function_call_element_ok():
+    code_py = """
+CONSTANT: u64[3] = (250, 250000, 250000000, )
+
+@exported
+def testEntry() -> u64:
+    return helper(CONSTANT[0])
+
+def helper(x: u64) -> u64:
+    return x
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 250 == result.returned_value
+
+@pytest.mark.integration_test
+def test_function_call_element_type_mismatch():
+    code_py = """
+CONSTANT: u64[3] = (250, 250000, 250000000, )
+
+@exported
+def testEntry() -> u8:
+    return helper(CONSTANT[0])
+
+def helper(x: u8) -> u8:
+    return x
+"""
+
+    with pytest.raises(Type3Exception, match=r'u8 must be u64 instead'):
+        Suite(code_py).run_code()
+
+@pytest.mark.integration_test
+def test_module_constant_type_mismatch_bitwidth():
+    code_py = """
+CONSTANT: u8[3] = (24, 57, 280, )
+"""
+
+    with pytest.raises(Type3Exception, match=r'Must fit in 1 byte\(s\)'):
+        Suite(code_py).run_code()
+
+@pytest.mark.integration_test
+def test_return_as_int():
+    code_py = """
+CONSTANT: u8[3] = (24, 57, 80, )
+
+def testEntry() -> u32:
+    return CONSTANT
+"""
+
+    with pytest.raises(Type3Exception, match=r'static_array \(u8\) \(3\) must be u32 instead'):
+        Suite(code_py).run_code()
+
+@pytest.mark.integration_test
+def test_module_constant_type_mismatch_not_subscriptable():
+    code_py = """
+CONSTANT: u8 = 24
+
+@exported
+def testEntry() -> u8:
+    return CONSTANT[0]
+"""
+
+    with pytest.raises(Type3Exception, match='u8 cannot be subscripted'):
+        Suite(code_py).run_code()
+
+@pytest.mark.integration_test
+def test_module_constant_type_mismatch_index_out_of_range_constant():
+    code_py = """
+CONSTANT: u8[3] = (24, 57, 80, )
+
+@exported
+def testEntry() -> u8:
+    return CONSTANT[3]
+"""
+
+    with pytest.raises(Type3Exception, match='3 must be less or equal than 2'):
+        Suite(code_py).run_code()
+
+@pytest.mark.integration_test
+def test_module_constant_type_mismatch_index_out_of_range_variable():
+    code_py = """
+CONSTANT: u8[3] = (24, 57, 80, )
+
+@exported
+def testEntry(x: u32) -> u8:
+    return CONSTANT[x]
+"""
+
+    with pytest.raises(RuntimeError):
+        Suite(code_py).run_code(3)
+
+@pytest.mark.integration_test
+def test_static_array_constant_too_few_values():
+    code_py = """
+CONSTANT: u8[4] = (24, 57, )
+
+@exported
+def testEntry() -> i32:
+    return 0
+"""
+
+    with pytest.raises(Type3Exception, match='Member count mismatch'):
+        Suite(code_py).run_code()
+
+@pytest.mark.integration_test
+def test_static_array_constant_too_many_values():
+    code_py = """
+CONSTANT: u8[3] = (24, 57, 1, 1, )
+
+@exported
+def testEntry() -> i32:
+    return 0
+"""
+
+    with pytest.raises(Type3Exception, match='Member count mismatch'):
+        Suite(code_py).run_code()
diff --git a/tests/integration/test_lang/test_struct.py b/tests/integration/test_lang/test_struct.py
new file mode 100644
index 0000000..bcef772
--- /dev/null
+++ b/tests/integration/test_lang/test_struct.py
@@ -0,0 +1,154 @@
+import pytest
+
+from phasm.type3.entry import Type3Exception
+
+from ..constants import (
+    ALL_INT_TYPES, TYPE_MAP
+)
+from ..helpers import Suite
+
+@pytest.mark.integration_test
+def test_module_constant_def():
+    code_py = """
+class SomeStruct:
+    value0: u8
+    value1: u32
+    value2: u64
+
+CONSTANT: SomeStruct = SomeStruct(250, 250000, 250000000)
+
+@exported
+def testEntry() -> i32:
+    return 0
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 0 == result.returned_value
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', ALL_INT_TYPES)
+def test_module_constant(type_):
+    code_py = f"""
+class CheckedValue:
+    value: {type_}
+
+CONSTANT: CheckedValue = CheckedValue(24)
+
+@exported
+def testEntry() -> {type_}:
+    return CONSTANT.value
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 24 == result.returned_value
+    assert TYPE_MAP[type_] == type(result.returned_value)
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', ALL_INT_TYPES)
+def test_struct_0(type_):
+    code_py = f"""
+class CheckedValue:
+    value: {type_}
+
+@exported
+def testEntry() -> {type_}:
+    return helper(CheckedValue(23))
+
+def helper(cv: CheckedValue) -> {type_}:
+    return cv.value
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 23 == result.returned_value
+
+@pytest.mark.integration_test
+def test_struct_1():
+    code_py = """
+class Rectangle:
+    height: i32
+    width: i32
+    border: i32
+
+@exported
+def testEntry() -> i32:
+    return helper(Rectangle(100, 150, 2))
+
+def helper(shape: Rectangle) -> i32:
+    return shape.height + shape.width + shape.border
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 252 == result.returned_value
+
+@pytest.mark.integration_test
+def test_struct_2():
+    code_py = """
+class Rectangle:
+    height: i32
+    width: i32
+    border: i32
+
+@exported
+def testEntry() -> i32:
+    return helper(Rectangle(100, 150, 2), Rectangle(200, 90, 3))
+
+def helper(shape1: Rectangle, shape2: Rectangle) -> i32:
+    return shape1.height + shape1.width + shape1.border + shape2.height + shape2.width + shape2.border
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 545 == result.returned_value
+
+@pytest.mark.integration_test
+def test_returned_struct():
+    code_py = """
+class CheckedValue:
+    value: u8
+
+CONSTANT: CheckedValue = CheckedValue(199)
+
+def helper() -> CheckedValue:
+    return CONSTANT
+
+def helper2(x: CheckedValue) -> u8:
+    return x.value
+
+@exported
+def testEntry() -> u8:
+    return helper2(helper())
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 199 == result.returned_value
+
+@pytest.mark.integration_test
+def test_type_mismatch_arg_module_constant():
+    code_py = """
+class Struct:
+    param: f32
+
+STRUCT: Struct = Struct(1)
+"""
+
+    with pytest.raises(Type3Exception, match='Must be real'):
+        Suite(code_py).run_code()
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', ['i32', 'i64', 'f32', 'f64'])
+def test_type_mismatch_struct_member(type_):
+    code_py = f"""
+class Struct:
+    param: {type_}
+
+def testEntry(arg: Struct) -> (i32, i32, ):
+    return arg.param
+"""
+
+    with pytest.raises(Type3Exception, match=type_ + r' must be tuple \(i32\) \(i32\) instead'):
+        Suite(code_py).run_code()
diff --git a/tests/integration/test_lang/test_tuple.py b/tests/integration/test_lang/test_tuple.py
new file mode 100644
index 0000000..a238932
--- /dev/null
+++ b/tests/integration/test_lang/test_tuple.py
@@ -0,0 +1,188 @@
+import pytest
+
+from phasm.type3.entry import Type3Exception
+
+from ..constants import ALL_FLOAT_TYPES, COMPLETE_INT_TYPES, TYPE_MAP
+from ..helpers import Suite
+
+@pytest.mark.integration_test
+def test_module_constant_def():
+    code_py = """
+CONSTANT: (u8, u32, u64, ) = (250, 250000, 250000000, )
+
+@exported
+def testEntry() -> i32:
+    return 0
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 0 == result.returned_value
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', ['u8', 'u32', 'u64', ])
+def test_module_constant_1(type_):
+    code_py = f"""
+CONSTANT: ({type_}, ) = (65, )
+
+@exported
+def testEntry() -> {type_}:
+    return CONSTANT[0]
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 65 == result.returned_value
+
+@pytest.mark.integration_test
+def test_module_constant_6():
+    code_py = """
+CONSTANT: (u8, u8, u32, u32, u64, u64, ) = (11, 22, 3333, 4444, 555555, 666666, )
+
+@exported
+def testEntry() -> u32:
+    return CONSTANT[2]
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 3333 == result.returned_value
+
+@pytest.mark.integration_test
+def test_function_call_element_ok():
+    code_py = """
+CONSTANT: (u8, u32, u64, ) = (250, 250000, 250000000, )
+
+@exported
+def testEntry() -> u64:
+    return helper(CONSTANT[2])
+
+def helper(x: u64) -> u64:
+    return x
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 250000000 == result.returned_value
+
+@pytest.mark.integration_test
+def test_function_call_element_type_mismatch():
+    code_py = """
+CONSTANT: (u8, u32, u64, ) = (250, 250000, 250000000, )
+
+@exported
+def testEntry() -> u8:
+    return helper(CONSTANT[2])
+
+def helper(x: u8) -> u8:
+    return x
+"""
+
+    with pytest.raises(Type3Exception, match=r'u8 must be u64 instead'):
+        Suite(code_py).run_code()
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', COMPLETE_INT_TYPES)
+def test_tuple_simple_constructor_int(type_):
+    code_py = f"""
+@exported
+def testEntry() -> {type_}:
+    return helper((24, 57, 80, ))
+
+def helper(vector: ({type_}, {type_}, {type_}, )) -> {type_}:
+    return vector[0] + vector[1] + vector[2]
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 161 == result.returned_value
+    assert TYPE_MAP[type_] == type(result.returned_value)
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', ALL_FLOAT_TYPES)
+def test_tuple_simple_constructor_float(type_):
+    code_py = f"""
+@exported
+def testEntry() -> {type_}:
+    return helper((1.0, 2.0, 3.0, ))
+
+def helper(v: ({type_}, {type_}, {type_}, )) -> {type_}:
+    return sqrt(v[0] * v[0] + v[1] * v[1] + v[2] * v[2])
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert 3.74 < result.returned_value < 3.75
+
+@pytest.mark.integration_test
+@pytest.mark.skip('SIMD support is but a dream')
+def test_tuple_i32x4():
+    code_py = """
+@exported
+def testEntry() -> i32x4:
+    return (51, 153, 204, 0, )
+"""
+
+    result = Suite(code_py).run_code()
+
+    assert (1, 2, 3, 0) == result.returned_value
+
+@pytest.mark.integration_test
+def test_assign_to_tuple_with_tuple():
+    code_py = """
+CONSTANT: (u32, ) = 0
+"""
+
+    with pytest.raises(Type3Exception, match='Must be tuple'):
+        Suite(code_py).run_code()
+
+@pytest.mark.integration_test
+def test_tuple_constant_too_few_values():
+    code_py = """
+CONSTANT: (u32, u8, u8, ) = (24, 57, )
+"""
+
+    with pytest.raises(Type3Exception, match='Tuple element count mismatch'):
+        Suite(code_py).run_code()
+
+@pytest.mark.integration_test
+def test_tuple_constant_too_many_values():
+    code_py = """
+CONSTANT: (u32, u8, u8, ) = (24, 57, 1, 1, )
+"""
+
+    with pytest.raises(Type3Exception, match='Tuple element count mismatch'):
+        Suite(code_py).run_code()
+
+@pytest.mark.integration_test
+def test_tuple_constant_type_mismatch():
+    code_py = """
+CONSTANT: (u32, u8, u8, ) = (24, 4000, 1, )
+"""
+
+    with pytest.raises(Type3Exception, match=r'Must fit in 1 byte\(s\)'):
+        Suite(code_py).run_code()
+
+@pytest.mark.integration_test
+def test_tuple_must_use_literal_for_indexing():
+    code_py = """
+CONSTANT: u32 = 0
+
+@exported
+def testEntry(x: (u8, u32, u64)) -> u64:
+    return x[CONSTANT]
+"""
+
+    with pytest.raises(Type3Exception, match='Must index with literal'):
+        Suite(code_py).run_code()
+
+@pytest.mark.integration_test
+def test_tuple_must_use_integer_for_indexing():
+    code_py = """
+@exported
+def testEntry(x: (u8, u32, u64)) -> u64:
+    return x[0.0]
+"""
+
+    with pytest.raises(Type3Exception, match='Must index with integer literal'):
+        Suite(code_py).run_code()
diff --git a/tests/integration/test_runtime_checks.py b/tests/integration/test_runtime_checks.py
deleted file mode 100644
index 97d6542..0000000
--- a/tests/integration/test_runtime_checks.py
+++ /dev/null
@@ -1,31 +0,0 @@
-import pytest
-
-from .helpers import Suite
-
-@pytest.mark.integration_test
-def test_bytes_index_out_of_bounds():
-    code_py = """
-@exported
-def testEntry(f: bytes) -> u8:
-    return f[50]
-"""
-
-    result = Suite(code_py).run_code(b'Short', b'Long' * 100)
-
-    assert 0 == result.returned_value
-
-@pytest.mark.integration_test
-def test_static_array_index_out_of_bounds():
-    code_py = """
-CONSTANT0: u32[3] = (24, 57, 80, )
-
-CONSTANT1: u32[16] = (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, )
-
-@exported
-def testEntry() -> u32:
-    return CONSTANT0[16]
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 0 == result.returned_value
diff --git a/tests/integration/test_simple.py b/tests/integration/test_simple.py
deleted file mode 100644
index f0c2993..0000000
--- a/tests/integration/test_simple.py
+++ /dev/null
@@ -1,571 +0,0 @@
-import pytest
-
-from .helpers import Suite
-
-TYPE_MAP = {
-    'u8': int,
-    'u32': int,
-    'u64': int,
-    'i32': int,
-    'i64': int,
-    'f32': float,
-    'f64': float,
-}
-
-COMPLETE_SIMPLE_TYPES = [
-    'u32', 'u64',
-    'i32', 'i64',
-    'f32', 'f64',
-]
-
-@pytest.mark.integration_test
-@pytest.mark.parametrize('type_', TYPE_MAP.keys())
-def test_return(type_):
-    code_py = f"""
-@exported
-def testEntry() -> {type_}:
-    return 13
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 13 == result.returned_value
-    assert TYPE_MAP[type_] == type(result.returned_value)
-
-@pytest.mark.integration_test
-@pytest.mark.parametrize('type_', COMPLETE_SIMPLE_TYPES)
-def test_addition(type_):
-    code_py = f"""
-@exported
-def testEntry() -> {type_}:
-    return 10 + 3
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 13 == result.returned_value
-    assert TYPE_MAP[type_] == type(result.returned_value)
-
-@pytest.mark.integration_test
-@pytest.mark.parametrize('type_', COMPLETE_SIMPLE_TYPES)
-def test_subtraction(type_):
-    code_py = f"""
-@exported
-def testEntry() -> {type_}:
-    return 10 - 3
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 7 == result.returned_value
-    assert TYPE_MAP[type_] == type(result.returned_value)
-
-@pytest.mark.integration_test
-@pytest.mark.parametrize('type_', ['u32', 'u64']) # FIXME: Support u8, requires an extra AND operation
-def test_logical_left_shift(type_):
-    code_py = f"""
-@exported
-def testEntry() -> {type_}:
-    return 10 << 3
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 80 == result.returned_value
-    assert TYPE_MAP[type_] == type(result.returned_value)
-
-@pytest.mark.integration_test
-@pytest.mark.parametrize('type_', ['u8', 'u32', 'u64'])
-def test_logical_right_shift(type_):
-    code_py = f"""
-@exported
-def testEntry() -> {type_}:
-    return 10 >> 3
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 1 == result.returned_value
-    assert TYPE_MAP[type_] == type(result.returned_value)
-
-@pytest.mark.integration_test
-@pytest.mark.parametrize('type_', ['u8', 'u32', 'u64'])
-def test_bitwise_or(type_):
-    code_py = f"""
-@exported
-def testEntry() -> {type_}:
-    return 10 | 3
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 11 == result.returned_value
-    assert TYPE_MAP[type_] == type(result.returned_value)
-
-@pytest.mark.integration_test
-@pytest.mark.parametrize('type_', ['u8', 'u32', 'u64'])
-def test_bitwise_xor(type_):
-    code_py = f"""
-@exported
-def testEntry() -> {type_}:
-    return 10 ^ 3
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 9 == result.returned_value
-    assert TYPE_MAP[type_] == type(result.returned_value)
-
-@pytest.mark.integration_test
-@pytest.mark.parametrize('type_', ['u8', 'u32', 'u64'])
-def test_bitwise_and(type_):
-    code_py = f"""
-@exported
-def testEntry() -> {type_}:
-    return 10 & 3
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 2 == result.returned_value
-    assert TYPE_MAP[type_] == type(result.returned_value)
-
-@pytest.mark.integration_test
-@pytest.mark.parametrize('type_', ['f32', 'f64'])
-def test_buildins_sqrt(type_):
-    code_py = f"""
-@exported
-def testEntry() -> {type_}:
-    return sqrt(25)
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 5 == result.returned_value
-    assert TYPE_MAP[type_] == type(result.returned_value)
-
-@pytest.mark.integration_test
-@pytest.mark.parametrize('type_', TYPE_MAP.keys())
-def test_arg(type_):
-    code_py = f"""
-@exported
-def testEntry(a: {type_}) -> {type_}:
-    return a
-"""
-
-    result = Suite(code_py).run_code(125)
-
-    assert 125 == result.returned_value
-    assert TYPE_MAP[type_] == type(result.returned_value)
-
-@pytest.mark.integration_test
-@pytest.mark.skip('Do we want it to work like this?')
-def test_i32_to_i64():
-    code_py = """
-@exported
-def testEntry(a: i32) -> i64:
-    return a
-"""
-
-    result = Suite(code_py).run_code(125)
-
-    assert 125 == result.returned_value
-
-@pytest.mark.integration_test
-@pytest.mark.skip('Do we want it to work like this?')
-def test_i32_plus_i64():
-    code_py = """
-@exported
-def testEntry(a: i32, b: i64) -> i64:
-    return a + b
-"""
-
-    result = Suite(code_py).run_code(125, 100)
-
-    assert 225 == result.returned_value
-
-@pytest.mark.integration_test
-@pytest.mark.skip('Do we want it to work like this?')
-def test_f32_to_f64():
-    code_py = """
-@exported
-def testEntry(a: f32) -> f64:
-    return a
-"""
-
-    result = Suite(code_py).run_code(125.5)
-
-    assert 125.5 == result.returned_value
-
-@pytest.mark.integration_test
-@pytest.mark.skip('Do we want it to work like this?')
-def test_f32_plus_f64():
-    code_py = """
-@exported
-def testEntry(a: f32, b: f64) -> f64:
-    return a + b
-"""
-
-    result = Suite(code_py).run_code(125.5, 100.25)
-
-    assert 225.75 == result.returned_value
-
-@pytest.mark.integration_test
-@pytest.mark.skip('TODO')
-def test_uadd():
-    code_py = """
-@exported
-def testEntry() -> i32:
-    return +523
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 523 == result.returned_value
-
-@pytest.mark.integration_test
-@pytest.mark.skip('TODO')
-def test_usub():
-    code_py = """
-@exported
-def testEntry() -> i32:
-    return -19
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert -19 == result.returned_value
-
-@pytest.mark.integration_test
-@pytest.mark.parametrize('inp', [9, 10, 11, 12])
-def test_if_simple(inp):
-    code_py = """
-@exported
-def testEntry(a: i32) -> i32:
-    if a > 10:
-        return 15
-
-    return 3
-"""
-    exp_result = 15 if inp > 10 else 3
-
-    suite = Suite(code_py)
-
-    result = suite.run_code(inp)
-    assert exp_result == result.returned_value
-
-@pytest.mark.integration_test
-@pytest.mark.skip('Such a return is not how things should be')
-def test_if_complex():
-    code_py = """
-@exported
-def testEntry(a: i32) -> i32:
-    if a > 10:
-        return 10
-    elif a > 0:
-        return a
-    else:
-        return 0
-
-    return -1 # Required due to function type
-"""
-
-    suite = Suite(code_py)
-
-    assert 10 == suite.run_code(20).returned_value
-    assert 10 == suite.run_code(10).returned_value
-
-    assert 8 == suite.run_code(8).returned_value
-
-    assert 0 == suite.run_code(0).returned_value
-    assert 0 == suite.run_code(-1).returned_value
-
-@pytest.mark.integration_test
-def test_if_nested():
-    code_py = """
-@exported
-def testEntry(a: i32, b: i32) -> i32:
-    if a > 11:
-        if b > 11:
-            return 3
-
-        return 2
-
-    if b > 11:
-        return 1
-
-    return 0
-"""
-
-    suite = Suite(code_py)
-
-    assert 3 == suite.run_code(20, 20).returned_value
-    assert 2 == suite.run_code(20, 10).returned_value
-    assert 1 == suite.run_code(10, 20).returned_value
-    assert 0 == suite.run_code(10, 10).returned_value
-
-@pytest.mark.integration_test
-def test_call_pre_defined():
-    code_py = """
-def helper(left: i32, right: i32) -> i32:
-    return left + right
-
-@exported
-def testEntry() -> i32:
-    return helper(10, 3)
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 13 == result.returned_value
-
-@pytest.mark.integration_test
-def test_call_post_defined():
-    code_py = """
-@exported
-def testEntry() -> i32:
-    return helper(10, 3)
-
-def helper(left: i32, right: i32) -> i32:
-    return left - right
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 7 == result.returned_value
-
-@pytest.mark.integration_test
-@pytest.mark.parametrize('type_', COMPLETE_SIMPLE_TYPES)
-def test_call_with_expression(type_):
-    code_py = f"""
-@exported
-def testEntry() -> {type_}:
-    return helper(10 + 20, 3 + 5)
-
-def helper(left: {type_}, right: {type_}) -> {type_}:
-    return left - right
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 22 == result.returned_value
-    assert TYPE_MAP[type_] == type(result.returned_value)
-
-@pytest.mark.integration_test
-@pytest.mark.skip('Not yet implemented')
-def test_assign():
-    code_py = """
-
-@exported
-def testEntry() -> i32:
-    a: i32 = 8947
-    return a
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 8947 == result.returned_value
-
-@pytest.mark.integration_test
-@pytest.mark.parametrize('type_', TYPE_MAP.keys())
-def test_struct_0(type_):
-    code_py = f"""
-class CheckedValue:
-    value: {type_}
-
-@exported
-def testEntry() -> {type_}:
-    return helper(CheckedValue(23))
-
-def helper(cv: CheckedValue) -> {type_}:
-    return cv.value
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 23 == result.returned_value
-
-@pytest.mark.integration_test
-def test_struct_1():
-    code_py = """
-class Rectangle:
-    height: i32
-    width: i32
-    border: i32
-
-@exported
-def testEntry() -> i32:
-    return helper(Rectangle(100, 150, 2))
-
-def helper(shape: Rectangle) -> i32:
-    return shape.height + shape.width + shape.border
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 252 == result.returned_value
-
-@pytest.mark.integration_test
-def test_struct_2():
-    code_py = """
-class Rectangle:
-    height: i32
-    width: i32
-    border: i32
-
-@exported
-def testEntry() -> i32:
-    return helper(Rectangle(100, 150, 2), Rectangle(200, 90, 3))
-
-def helper(shape1: Rectangle, shape2: Rectangle) -> i32:
-    return shape1.height + shape1.width + shape1.border + shape2.height + shape2.width + shape2.border
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 545 == result.returned_value
-
-@pytest.mark.integration_test
-@pytest.mark.parametrize('type_', COMPLETE_SIMPLE_TYPES)
-def test_tuple_simple_constructor(type_):
-    code_py = f"""
-@exported
-def testEntry() -> {type_}:
-    return helper((24, 57, 80, ))
-
-def helper(vector: ({type_}, {type_}, {type_}, )) -> {type_}:
-    return vector[0] + vector[1] + vector[2]
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 161 == result.returned_value
-    assert TYPE_MAP[type_] == type(result.returned_value)
-
-@pytest.mark.integration_test
-def test_tuple_float():
-    code_py = """
-@exported
-def testEntry() -> f32:
-    return helper((1.0, 2.0, 3.0, ))
-
-def helper(v: (f32, f32, f32, )) -> f32:
-    return sqrt(v[0] * v[0] + v[1] * v[1] + v[2] * v[2])
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 3.74 < result.returned_value < 3.75
-
-@pytest.mark.integration_test
-@pytest.mark.parametrize('type_', COMPLETE_SIMPLE_TYPES)
-def test_static_array_module_constant(type_):
-    code_py = f"""
-CONSTANT: {type_}[3] = (24, 57, 80, )
-
-@exported
-def testEntry() -> {type_}:
-    return helper(CONSTANT)
-
-def helper(array: {type_}[3]) -> {type_}:
-    return array[0] + array[1] + array[2]
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 161 == result.returned_value
-    assert TYPE_MAP[type_] == type(result.returned_value)
-
-@pytest.mark.integration_test
-@pytest.mark.parametrize('type_', COMPLETE_SIMPLE_TYPES)
-def test_static_array_indexed(type_):
-    code_py = f"""
-CONSTANT: {type_}[3] = (24, 57, 80, )
-
-@exported
-def testEntry() -> {type_}:
-    return helper(CONSTANT, 0, 1, 2)
-
-def helper(array: {type_}[3], i0: u32, i1: u32, i2: u32) -> {type_}:
-    return array[i0] + array[i1] + array[i2]
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert 161 == result.returned_value
-    assert TYPE_MAP[type_] == type(result.returned_value)
-
-@pytest.mark.integration_test
-def test_bytes_address():
-    code_py = """
-@exported
-def testEntry(f: bytes) -> bytes:
-    return f
-"""
-
-    result = Suite(code_py).run_code(b'This is a test')
-
-    # THIS DEPENDS ON THE ALLOCATOR
-    # A different allocator will return a different value
-    assert 20 == result.returned_value
-
-@pytest.mark.integration_test
-def test_bytes_length():
-    code_py = """
-@exported
-def testEntry(f: bytes) -> i32:
-    return len(f)
-"""
-
-    result = Suite(code_py).run_code(b'This is another test')
-
-    assert 20 == result.returned_value
-
-@pytest.mark.integration_test
-def test_bytes_index():
-    code_py = """
-@exported
-def testEntry(f: bytes) -> u8:
-    return f[8]
-"""
-
-    result = Suite(code_py).run_code(b'This is another test')
-
-    assert 0x61 == result.returned_value
-
-@pytest.mark.integration_test
-@pytest.mark.skip('SIMD support is but a dream')
-def test_tuple_i32x4():
-    code_py = """
-@exported
-def testEntry() -> i32x4:
-    return (51, 153, 204, 0, )
-"""
-
-    result = Suite(code_py).run_code()
-
-    assert (1, 2, 3, 0) == result.returned_value
-
-@pytest.mark.integration_test
-def test_imported():
-    code_py = """
-@imported
-def helper(mul: i32) -> i32:
-    pass
-
-@exported
-def testEntry() -> i32:
-    return helper(2)
-"""
-
-    def helper(mul: int) -> int:
-        return 4238 * mul
-
-    result = Suite(code_py).run_code(
-        runtime='wasmer',
-        imports={
-            'helper': helper,
-        }
-    )
-
-    assert 8476 == result.returned_value
diff --git a/tests/integration/test_static_checking.py b/tests/integration/test_static_checking.py
deleted file mode 100644
index 1544537..0000000
--- a/tests/integration/test_static_checking.py
+++ /dev/null
@@ -1,109 +0,0 @@
-import pytest
-
-from phasm.parser import phasm_parse
-from phasm.exceptions import StaticError
-
-@pytest.mark.integration_test
-@pytest.mark.parametrize('type_', ['i32', 'i64', 'f32', 'f64'])
-def test_type_mismatch_function_argument(type_):
-    code_py = f"""
-def helper(a: {type_}) -> (i32, i32, ):
-    return a
-"""
-
-    with pytest.raises(StaticError, match=f'Static error on line 3: Expected \\(i32, i32, \\), a is actually {type_}'):
-        phasm_parse(code_py)
-
-@pytest.mark.integration_test
-@pytest.mark.parametrize('type_', ['i32', 'i64', 'f32', 'f64'])
-def test_type_mismatch_struct_member(type_):
-    code_py = f"""
-class Struct:
-    param: {type_}
-
-def testEntry(arg: Struct) -> (i32, i32, ):
-    return arg.param
-"""
-
-    with pytest.raises(StaticError, match=f'Static error on line 6: Expected \\(i32, i32, \\), arg.param is actually {type_}'):
-        phasm_parse(code_py)
-
-@pytest.mark.integration_test
-@pytest.mark.parametrize('type_', ['i32', 'i64', 'f32', 'f64'])
-def test_type_mismatch_tuple_member(type_):
-    code_py = f"""
-def testEntry(arg: ({type_}, )) -> (i32, i32, ):
-    return arg[0]
-"""
-
-    with pytest.raises(StaticError, match=f'Static error on line 3: Expected \\(i32, i32, \\), arg\\[0\\] is actually {type_}'):
-        phasm_parse(code_py)
-
-@pytest.mark.integration_test
-@pytest.mark.parametrize('type_', ['i32', 'i64', 'f32', 'f64'])
-def test_type_mismatch_function_result(type_):
-    code_py = f"""
-def helper() -> {type_}:
-    return 1
-
-@exported
-def testEntry() -> (i32, i32, ):
-    return helper()
-"""
-
-    with pytest.raises(StaticError, match=f'Static error on line 7: Expected \\(i32, i32, \\), helper actually returns {type_}'):
-        phasm_parse(code_py)
-
-@pytest.mark.integration_test
-def test_tuple_constant_too_few_values():
-    code_py = """
-CONSTANT: (u32, u8, u8, ) = (24, 57, )
-"""
-
-    with pytest.raises(StaticError, match='Static error on line 2: Invalid number of tuple values'):
-        phasm_parse(code_py)
-
-@pytest.mark.integration_test
-def test_tuple_constant_too_many_values():
-    code_py = """
-CONSTANT: (u32, u8, u8, ) = (24, 57, 1, 1, )
-"""
-
-    with pytest.raises(StaticError, match='Static error on line 2: Invalid number of tuple values'):
-        phasm_parse(code_py)
-
-@pytest.mark.integration_test
-def test_tuple_constant_type_mismatch():
-    code_py = """
-CONSTANT: (u32, u8, u8, ) = (24, 4000, 1, )
-"""
-
-    with pytest.raises(StaticError, match='Static error on line 2: Integer value out of range; expected 0..255, actual 4000'):
-        phasm_parse(code_py)
-
-@pytest.mark.integration_test
-def test_static_array_constant_too_few_values():
-    code_py = """
-CONSTANT: u8[3] = (24, 57, )
-"""
-
-    with pytest.raises(StaticError, match='Static error on line 2: Invalid number of static array values'):
-        phasm_parse(code_py)
-
-@pytest.mark.integration_test
-def test_static_array_constant_too_many_values():
-    code_py = """
-CONSTANT: u8[3] = (24, 57, 1, 1, )
-"""
-
-    with pytest.raises(StaticError, match='Static error on line 2: Invalid number of static array values'):
-        phasm_parse(code_py)
-
-@pytest.mark.integration_test
-def test_static_array_constant_type_mismatch():
-    code_py = """
-CONSTANT: u8[3] = (24, 4000, 1, )
-"""
-
-    with pytest.raises(StaticError, match='Static error on line 2: Integer value out of range; expected 0..255, actual 4000'):
-        phasm_parse(code_py)
diff --git a/tests/integration/test_stdlib/__init__.py b/tests/integration/test_stdlib/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/integration/test_stdlib_alloc.py b/tests/integration/test_stdlib/test_alloc.py
similarity index 95%
rename from tests/integration/test_stdlib_alloc.py
rename to tests/integration/test_stdlib/test_alloc.py
index da8ccea..96d1fd6 100644
--- a/tests/integration/test_stdlib_alloc.py
+++ b/tests/integration/test_stdlib/test_alloc.py
@@ -2,8 +2,8 @@ import sys
 
 import pytest
 
-from .helpers import write_header
-from .runners import RunnerPywasm3 as Runner
+from ..helpers import write_header
+from ..runners import RunnerPywasm3 as Runner
 
 def setup_interpreter(phash_code: str) -> Runner:
     runner = Runner(phash_code)