Implements sum for Foldable types

Foldable take a TypeConstructor. The first argument must be a
NatNum.

TODO.md

@@ -12,9 +12,12 @@
 - Also, check the codes for FIXME and TODO
 - Allocation is done using pointers for members, is this desired?
 - See if we want to replace Fractional with Real, and add Rational, Irrationl, Algebraic, Transendental
+  - Implement q32? q64? Two i32/i64 divided?
 - Does Subscript do what we want? It's a language feature rather a normal typed thing. How would you implement your own Subscript-able type?
   - Clean up Subscript implementation - it's half implemented in the compiler. Makes more sense to move more parts to stdlib_types.
 - Have a set of rules or guidelines for the constraint comments, they're messy.
+- Do we need to store the placeholders on the expressions? They're only temporary while the type checker is running
+  - Might not even need to store them at all outside the generated constraints?
 
 - Parser is putting stuff in ModuleDataBlock
   - Surely the compiler should build data blocks

phasm/codestyle.py

@@ -6,7 +6,6 @@ It's intented to be a "any color, as long as it's black" kind of renderer
 from typing import Generator
 
 from . import ourlang, prelude
-from .type3.placeholders import TYPE3_ASSERTION_ERROR, Type3OrPlaceholder
 from .type3.types import Type3
 
 
@@ -18,12 +17,10 @@ def phasm_render(inp: ourlang.Module) -> str:
 
 Statements = Generator[str, None, None]
 
-def type3(inp: Type3OrPlaceholder) -> str:
+def type3(inp: Type3) -> str:
     """
     Render: type's name
     """
-    assert isinstance(inp, Type3), TYPE3_ASSERTION_ERROR
-
     if inp is prelude.none:
         return 'None'
 

phasm/compiler.py

@@ -2,18 +2,19 @@
 This module contains the code to convert parsed Ourlang into WebAssembly code
 """
 import struct
-from typing import Dict, List, Optional
+from typing import Dict, List, Optional, Union
 
 from . import codestyle, ourlang, prelude, wasm
 from .runtime import calculate_alloc_size, calculate_member_offset
 from .stdlib import alloc as stdlib_alloc
 from .stdlib import types as stdlib_types
 from .type3 import functions as type3functions
-from .type3 import placeholders as type3placeholders
 from .type3 import typeclasses as type3classes
 from .type3 import types as type3types
 from .wasmgenerator import Generator as WasmGenerator
 
+TYPE3_ASSERTION_ERROR = 'You must call phasm_type3 after calling phasm_parse before your program can be compiled'
+
 LOAD_STORE_TYPE_MAP = {
     'i8': 'i32', # Have to use an u32, since there is no native i8 type
     'u8': 'i32', # Have to use an u32, since there is no native u8 type
@@ -259,6 +260,10 @@ INSTANCES = {
     prelude.Promotable.methods['demote']: {
         'a=f32,b=f64': stdlib_types.f32_f64_demote,
     },
+    prelude.Foldable.methods['sum']: {
+        'a=i32,t=i32[4]': stdlib_types.static_array_i32_4_sum,
+        'a=i32,t=i32[5]': stdlib_types.static_array_i32_5_sum,
+    },
 }
 
 def phasm_compile(inp: ourlang.Module) -> wasm.Module:
@@ -268,14 +273,14 @@ def phasm_compile(inp: ourlang.Module) -> wasm.Module:
     """
     return module(inp)
 
-def type3(inp: type3placeholders.Type3OrPlaceholder) -> wasm.WasmType:
+def type3(inp: type3types.Type3) -> wasm.WasmType:
     """
     Compile: type
 
     Types are used for example in WebAssembly function parameters
     and return types.
     """
-    assert isinstance(inp, type3types.Type3), type3placeholders.TYPE3_ASSERTION_ERROR
+    assert inp is not None, TYPE3_ASSERTION_ERROR
 
     if inp == prelude.none:
         return wasm.WasmTypeNone()
@@ -327,7 +332,7 @@ def tuple_instantiation(wgn: WasmGenerator, inp: ourlang.TupleInstantiation) ->
     """
     Compile: Instantiation (allocation) of a tuple
     """
-    assert isinstance(inp.type3, type3types.Type3)
+    assert inp.type3 is not None, TYPE3_ASSERTION_ERROR
 
     args: list[type3types.Type3] = []
 
@@ -345,7 +350,7 @@ def tuple_instantiation(wgn: WasmGenerator, inp: ourlang.TupleInstantiation) ->
 
     comment_elements = ''
     for element in inp.elements:
-        assert isinstance(element.type3, type3types.Type3), type3placeholders.TYPE3_ASSERTION_ERROR
+        assert element.type3 is not None, TYPE3_ASSERTION_ERROR
         comment_elements += f'{element.type3.name}, '
 
     tmp_var = wgn.temp_var_i32('tuple_adr')
@@ -359,17 +364,11 @@ def tuple_instantiation(wgn: WasmGenerator, inp: ourlang.TupleInstantiation) ->
     # Store each element individually
     offset = 0
     for element, exp_type3 in zip(inp.elements, args, strict=True):
-        if isinstance(exp_type3, type3placeholders.PlaceholderForType):
-            assert exp_type3.resolve_as is not None
-            assert isinstance(exp_type3.resolve_as, type3types.Type3)
-            exp_type3 = exp_type3.resolve_as
-
         assert element.type3 == exp_type3
 
         if (prelude.InternalPassAsPointer, (exp_type3, )) in prelude.PRELUDE_TYPE_CLASS_INSTANCES_EXISTING:
             mtyp = 'i32'
         else:
-            assert isinstance(exp_type3, type3types.Type3), NotImplementedError('Tuple of applied types / structs')
             mtyp = LOAD_STORE_TYPE_MAP[exp_type3.name]
 
         wgn.add_statement('nop', comment='PRE')
@@ -392,7 +391,7 @@ def expression(wgn: WasmGenerator, inp: ourlang.Expression) -> None:
         raise Exception
 
     if isinstance(inp, ourlang.ConstantPrimitive):
-        assert isinstance(inp.type3, type3types.Type3), type3placeholders.TYPE3_ASSERTION_ERROR
+        assert inp.type3 is not None, TYPE3_ASSERTION_ERROR
 
         if inp.type3 in (prelude.i8, prelude.u8, ):
             # No native u8 type - treat as i32, with caution
@@ -433,7 +432,7 @@ def expression(wgn: WasmGenerator, inp: ourlang.Expression) -> None:
             return
 
         if isinstance(inp.variable, ourlang.ModuleConstantDef):
-            assert isinstance(inp.type3, type3types.Type3), type3placeholders.TYPE3_ASSERTION_ERROR
+            assert inp.type3 is not None, TYPE3_ASSERTION_ERROR
 
             if (prelude.InternalPassAsPointer, (inp.type3, )) in prelude.PRELUDE_TYPE_CLASS_INSTANCES_EXISTING:
                 assert isinstance(inp.variable.constant, (ourlang.ConstantBytes, ourlang.ConstantStruct, ourlang.ConstantTuple, ))
@@ -443,28 +442,25 @@ def expression(wgn: WasmGenerator, inp: ourlang.Expression) -> None:
                 wgn.i32.const(address)
                 return
 
-            if isinstance(inp.type3, type3types.Type3):
             expression(wgn, inp.variable.constant)
             return
 
-            raise NotImplementedError(expression, inp)
-
         raise NotImplementedError(expression, inp.variable)
 
     if isinstance(inp, ourlang.BinaryOp):
         expression(wgn, inp.left)
         expression(wgn, inp.right)
 
-        assert isinstance(inp.type3, type3types.Type3), type3placeholders.TYPE3_ASSERTION_ERROR
+        assert inp.type3 is not None, TYPE3_ASSERTION_ERROR
 
-        type_var_map: Dict[type3functions.TypeVariable, type3types.Type3] = {}
+        type_var_map: Dict[Union[type3functions.TypeVariable, type3functions.TypeConstructorVariable], type3types.Type3] = {}
 
         for type_var, arg_expr in zip(inp.operator.signature.args, [inp.left, inp.right, inp], strict=True):
             if not isinstance(type_var, type3functions.TypeVariable):
                 # Fixed type, not part of the lookup requirements
                 continue
 
-            assert isinstance(arg_expr.type3, type3types.Type3), type3placeholders.TYPE3_ASSERTION_ERROR
+            assert arg_expr.type3 is not None, TYPE3_ASSERTION_ERROR
             type_var_map[type_var] = arg_expr.type3
 
         instance_key = ','.join(
@@ -488,12 +484,16 @@ def expression(wgn: WasmGenerator, inp: ourlang.Expression) -> None:
             type_var_map = {}
 
             for type_var, arg_expr in zip(inp.function.signature.args, inp.arguments + [inp], strict=True):
-                if not isinstance(type_var, type3functions.TypeVariable):
+                if isinstance(type_var, type3types.Type3):
                     # Fixed type, not part of the lookup requirements
                     continue
 
-                assert isinstance(arg_expr.type3, type3types.Type3), type3placeholders.TYPE3_ASSERTION_ERROR
+                if isinstance(type_var, (type3functions.TypeVariable, type3functions.TypeConstructorVariable, )):
+                    assert arg_expr.type3 is not None, TYPE3_ASSERTION_ERROR
                     type_var_map[type_var] = arg_expr.type3
+                    continue
+
+                raise NotImplementedError
 
             instance_key = ','.join(
                 f'{k.letter}={v.name}'
@@ -515,7 +515,7 @@ def expression(wgn: WasmGenerator, inp: ourlang.Expression) -> None:
         return
 
     if isinstance(inp, ourlang.Subscript):
-        assert isinstance(inp.varref.type3, type3types.Type3), type3placeholders.TYPE3_ASSERTION_ERROR
+        assert inp.varref.type3 is not None, TYPE3_ASSERTION_ERROR
 
         if inp.varref.type3 is prelude.bytes_:
             expression(wgn, inp.varref)
@@ -523,7 +523,7 @@ def expression(wgn: WasmGenerator, inp: ourlang.Expression) -> None:
             wgn.call(stdlib_types.__subscript_bytes__)
             return
 
-        assert isinstance(inp.varref.type3, type3types.Type3)
+        assert inp.varref.type3 is not None, TYPE3_ASSERTION_ERROR
 
         sa_args = prelude.static_array.did_construct(inp.varref.type3)
         if sa_args is not None:
@@ -549,7 +549,6 @@ def expression(wgn: WasmGenerator, inp: ourlang.Expression) -> None:
                 wgn.i32.mul()
                 wgn.i32.add()
 
-                assert isinstance(el_type, type3types.Type3), NotImplementedError('Tuple of applied types / structs')
                 mtyp = LOAD_STORE_TYPE_MAP[el_type.name]
 
                 wgn.add_statement(f'{mtyp}.load')
@@ -562,18 +561,17 @@ def expression(wgn: WasmGenerator, inp: ourlang.Expression) -> None:
 
                 offset = 0
                 for el_type in tp_args[0:inp.index.value]:
-                    assert isinstance(el_type, type3types.Type3), type3placeholders.TYPE3_ASSERTION_ERROR
+                    assert el_type is not None, TYPE3_ASSERTION_ERROR
                     offset += calculate_alloc_size(el_type)
 
                 el_type = tp_args[inp.index.value]
-                assert isinstance(el_type, type3types.Type3), type3placeholders.TYPE3_ASSERTION_ERROR
+                assert el_type is not None, TYPE3_ASSERTION_ERROR
 
                 expression(wgn, inp.varref)
 
                 if (prelude.InternalPassAsPointer, (el_type, )) in prelude.PRELUDE_TYPE_CLASS_INSTANCES_EXISTING:
                     mtyp = 'i32'
                 else:
-                    assert isinstance(el_type, type3types.Type3), NotImplementedError('Tuple of applied types / structs')
                     mtyp = LOAD_STORE_TYPE_MAP[el_type.name]
 
                 wgn.add_statement(f'{mtyp}.load', f'offset={offset}')
@@ -582,14 +580,13 @@ def expression(wgn: WasmGenerator, inp: ourlang.Expression) -> None:
         raise NotImplementedError(expression, inp, inp.varref.type3)
 
     if isinstance(inp, ourlang.AccessStructMember):
-        assert isinstance(inp.struct_type3, type3types.Type3), type3placeholders.TYPE3_ASSERTION_ERROR
+        assert inp.struct_type3 is not None, TYPE3_ASSERTION_ERROR
 
         st_args = prelude.struct.did_construct(inp.struct_type3)
         assert st_args is not None
 
         member_type = st_args[inp.member]
 
-        assert isinstance(member_type, type3types.Type3), NotImplementedError('Tuple of applied types / structs')
         mtyp = LOAD_STORE_TYPE_MAP[member_type.name]
 
         expression(wgn, inp.varref)
@@ -608,7 +605,7 @@ def expression_fold(wgn: WasmGenerator, inp: ourlang.Fold) -> None:
     """
     Compile: Fold expression
     """
-    assert isinstance(inp.type3, type3types.Type3), type3placeholders.TYPE3_ASSERTION_ERROR
+    assert inp.type3 is not None, TYPE3_ASSERTION_ERROR
 
     if inp.iter.type3 is not prelude.bytes_:
         raise NotImplementedError(expression_fold, inp, inp.iter.type3)
@@ -839,7 +836,7 @@ def module_data(inp: ourlang.ModuleData) -> bytes:
         data_list: List[bytes] = []
 
         for constant in block.data:
-            assert isinstance(constant.type3, type3types.Type3), (id(constant), type3placeholders.TYPE3_ASSERTION_ERROR)
+            assert constant.type3 is not None, TYPE3_ASSERTION_ERROR
 
             if isinstance(constant, ourlang.ConstantMemoryStored) and block is not constant.data_block:
                 # It's stored in a different block
@@ -960,6 +957,7 @@ def module(inp: ourlang.Module) -> wasm.Module:
         stdlib_types.__u32_pow2__,
         stdlib_types.__u8_rotl__,
         stdlib_types.__u8_rotr__,
+        stdlib_types.__sa_i32_sum__,
     ] + [
         function(x)
         for x in inp.functions.values()

phasm/ourlang.py

@@ -6,7 +6,6 @@ from typing import Dict, Iterable, List, Optional, Union
 
 from . import prelude
 from .type3.functions import FunctionSignature, TypeVariableContext
-from .type3.placeholders import PlaceholderForType, Type3OrPlaceholder
 from .type3.typeclasses import Type3ClassMethod
 from .type3.types import Type3
 
@@ -17,10 +16,10 @@ class Expression:
     """
     __slots__ = ('type3', )
 
-    type3: Type3OrPlaceholder
+    type3: Type3 | None
 
     def __init__(self) -> None:
-        self.type3 = PlaceholderForType([self])
+        self.type3 = None
 
 class Constant(Expression):
     """
@@ -198,10 +197,10 @@ class AccessStructMember(Expression):
     __slots__ = ('varref', 'struct_type3', 'member', )
 
     varref: VariableReference
-    struct_type3: Type3OrPlaceholder
+    struct_type3: Type3
     member: str
 
-    def __init__(self, varref: VariableReference,  struct_type3: Type3OrPlaceholder, member: str) -> None:
+    def __init__(self, varref: VariableReference,  struct_type3: Type3, member: str) -> None:
         super().__init__()
 
         self.varref = varref
@@ -284,7 +283,7 @@ class FunctionParam:
     __slots__ = ('name', 'type3', )
 
     name: str
-    type3: Type3OrPlaceholder
+    type3: Type3
 
     def __init__(self, name: str, type3: Type3) -> None:
         self.name = name

phasm/parser.py

@@ -163,8 +163,8 @@ class OurVisitor:
 
             arg_type = self.visit_type(module, arg.annotation)
 
-            # if isisntance(arg_type, TypeVariable):
-            #   arg_type = PlaceHolderForType()
+            # FIXME: Allow TypeVariable in the function signature
+            # This would also require FunctionParam to accept a placeholder
 
             function.signature.args.append(arg_type)
             function.posonlyargs.append(FunctionParam(

phasm/prelude/__init__.py

@@ -1,20 +1,27 @@
 """
 The prelude are all the builtin types, type classes and methods
 """
+from typing import Any, Union
 
-from ..type3.functions import TypeVariable
+from ..type3.functions import (
+    Constraint_TypeClassInstanceExists,
+    TypeConstructorVariable,
+    TypeVariable,
+)
 from ..type3.typeclasses import Type3Class
 from ..type3.types import (
+    IntType3,
     Type3,
+    TypeConstructor,
     TypeConstructor_StaticArray,
     TypeConstructor_Struct,
     TypeConstructor_Tuple,
 )
 
-PRELUDE_TYPE_CLASS_INSTANCES_EXISTING: set[tuple[Type3Class, tuple[Type3, ...]]] = set()
+PRELUDE_TYPE_CLASS_INSTANCES_EXISTING: set[tuple[Type3Class, tuple[Union[Type3, TypeConstructor[Any], TypeConstructor_Struct], ...]]] = set()
 
 
-def instance_type_class(cls: Type3Class, *typ: Type3) -> None:
+def instance_type_class(cls: Type3Class, *typ: Union[Type3, TypeConstructor[Any], TypeConstructor_Struct]) -> None:
     global PRELUDE_TYPE_CLASS_INSTANCES_EXISTING
 
     # TODO: Check for required existing instantiations
@@ -93,7 +100,7 @@ bytes_ = Type3('bytes')
 This is a runtime-determined length piece of memory that can be indexed at runtime.
 """
 
-def sa_on_create(typ: Type3) -> None:
+def sa_on_create(args: tuple[Type3, IntType3], typ: Type3) -> None:
     instance_type_class(InternalPassAsPointer, typ)
 
 static_array = TypeConstructor_StaticArray('static_array', on_create=sa_on_create)
@@ -106,7 +113,7 @@ It should be applied with one argument. It has a runtime-dynamic length
 of the same type repeated.
 """
 
-def tp_on_create(typ: Type3) -> None:
+def tp_on_create(args: tuple[Type3, ...], typ: Type3) -> None:
     instance_type_class(InternalPassAsPointer, typ)
 
 tuple_ = TypeConstructor_Tuple('tuple', on_create=tp_on_create)
@@ -143,6 +150,7 @@ PRELUDE_TYPES: dict[str, Type3] = {
 a = TypeVariable('a')
 b = TypeVariable('b')
 
+t = TypeConstructorVariable('t', [])
 
 InternalPassAsPointer = Type3Class('InternalPassAsPointer', [a], methods={}, operators={})
 """
@@ -286,6 +294,14 @@ Promotable = Type3Class('Promotable', [a, b], methods={
 
 instance_type_class(Promotable, f32, f64)
 
+Foldable = Type3Class('Foldable', [t], methods={
+    'sum': [t(a), a],
+}, operators={}, additional_context={
+    'sum': [Constraint_TypeClassInstanceExists(NatNum, [a])],
+})
+
+instance_type_class(Foldable, static_array)
+
 PRELUDE_TYPE_CLASSES = {
     'Eq': Eq,
     'Ord': Ord,
@@ -321,4 +337,5 @@ PRELUDE_METHODS = {
     **Sized_.methods,
     **Extendable.methods,
     **Promotable.methods,
+    **Foldable.methods,
 }

phasm/stdlib/types.py

@@ -384,6 +384,50 @@ def __u8_rotr__(g: Generator, x: i32, r: i32) -> i32:
 
     return i32('return') # To satisfy mypy
 
+@func_wrapper()
+def __sa_i32_sum__(g: Generator, adr: i32, arlen: i32) -> i32:
+    i32_size = 4
+
+    s = i32('s')
+    stop = i32('stop')
+
+    # stop = adr + ar_len * i32_size
+    g.local.get(adr)
+    g.local.get(arlen)
+    g.i32.const(i32_size)
+    g.i32.mul()
+    g.i32.add()
+    g.local.set(stop)
+
+    # sum = 0
+    g.i32.const(0)
+    g.local.set(s)
+
+    with g.loop():
+        # sum = sum + *adr
+        g.local.get(adr)
+        g.i32.load()
+        g.local.get(s)
+        g.i32.add()
+        g.local.set(s)
+
+        # adr = adr + i32_size
+        g.local.get(adr)
+        g.i32.const(i32_size)
+        g.i32.add()
+        g.local.tee(adr)
+
+        # loop if adr < stop
+        g.local.get(stop)
+        g.i32.lt_u()
+        g.br_if(0)
+
+    # return sum
+    g.local.get(s)
+    g.return_()
+
+    return i32('return') # To satisfy mypy
+
 ## ###
 ## class Eq
 
@@ -920,3 +964,11 @@ def f32_f64_promote(g: Generator) -> None:
 
 def f32_f64_demote(g: Generator) -> None:
     g.f32.demote_f64()
+
+def static_array_i32_4_sum(g: Generator) -> None:
+    g.i32.const(4)
+    g.add_statement('call $stdlib.types.__sa_i32_sum__')
+
+def static_array_i32_5_sum(g: Generator) -> None:
+    g.i32.const(5)
+    g.add_statement('call $stdlib.types.__sa_i32_sum__')

phasm/type3/constraints.py

@@ -3,10 +3,11 @@ 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, List, Optional, Tuple, Union
+from typing import Any, Dict, Iterable, List, Optional, Tuple, Union
 
 from .. import ourlang, prelude
 from . import placeholders, typeclasses, types
+from .placeholders import PlaceholderForType
 
 
 class Error:
@@ -48,7 +49,7 @@ class Context:
     __slots__ = ('type_class_instances_existing', )
 
     # Constraint_TypeClassInstanceExists
-    type_class_instances_existing: set[tuple[typeclasses.Type3Class, tuple[types.Type3, ...]]]
+    type_class_instances_existing: set[tuple[typeclasses.Type3Class, tuple[Union[types.Type3, types.TypeConstructor[Any], types.TypeConstructor_Struct], ...]]]
 
     def __init__(self) -> None:
         self.type_class_instances_existing = set()
@@ -157,7 +158,7 @@ class SameTypeConstraint(ConstraintBase):
         return f'SameTypeConstraint({args}, comment={repr(self.comment)})'
 
 class TupleMatchConstraint(ConstraintBase):
-    def __init__(self, exp_type: placeholders.Type3OrPlaceholder, args: List[placeholders.Type3OrPlaceholder], comment: str):
+    def __init__(self, exp_type: placeholders.Type3OrPlaceholder, args: Iterable[placeholders.Type3OrPlaceholder], comment: str):
         super().__init__(comment=comment)
 
         self.exp_type = exp_type
@@ -348,8 +349,12 @@ class LiteralFitsConstraint(ConstraintBase):
                     LiteralFitsConstraint(x, y)
                     for x, y in zip(tp_args, self.literal.value, strict=True)
                 )
+
+                # Generate placeholders so each Literal expression
+                # gets updated when we figure out the type of the
+                # expression the literal is used in
                 res.extend(
-                    SameTypeConstraint(x, y.type3)
+                    SameTypeConstraint(x, PlaceholderForType([y]))
                     for x, y in zip(tp_args, self.literal.value, strict=True)
                 )
 
@@ -371,8 +376,12 @@ class LiteralFitsConstraint(ConstraintBase):
                     LiteralFitsConstraint(sa_type, y)
                     for y in self.literal.value
                 )
+
+                # Generate placeholders so each Literal expression
+                # gets updated when we figure out the type of the
+                # expression the literal is used in
                 res.extend(
-                    SameTypeConstraint(sa_type, y.type3)
+                    SameTypeConstraint(sa_type, PlaceholderForType([y]))
                     for y in self.literal.value
                 )
 
@@ -396,8 +405,12 @@ class LiteralFitsConstraint(ConstraintBase):
                 LiteralFitsConstraint(x, y)
                 for x, y in zip(st_args.values(), self.literal.value, strict=True)
             )
+
+            # Generate placeholders so each Literal expression
+            # gets updated when we figure out the type of the
+            # expression the literal is used in
             res.extend(
-                SameTypeConstraint(x_t, y.type3, comment=f'{self.literal.struct_name}.{x_n}')
+                SameTypeConstraint(x_t, PlaceholderForType([y]), comment=f'{self.literal.struct_name}.{x_n}')
                 for (x_n, x_t, ), y in zip(st_args.items(), self.literal.value, strict=True)
             )
 
@@ -421,20 +434,27 @@ 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', )
+    __slots__ = ('ret_type3', 'type3', 'index', 'index_phft', )
 
     ret_type3: placeholders.Type3OrPlaceholder
     type3: placeholders.Type3OrPlaceholder
     index: ourlang.Expression
-    index_type3: placeholders.Type3OrPlaceholder
+    index_phft: placeholders.Type3OrPlaceholder
 
-    def __init__(self, ret_type3: placeholders.Type3OrPlaceholder, type3: placeholders.Type3OrPlaceholder, index: ourlang.Expression, comment: Optional[str] = None) -> None:
+    def __init__(
+            self,
+            ret_type3: placeholders.PlaceholderForType,
+            type3: placeholders.PlaceholderForType,
+            index: ourlang.Expression,
+            index_phft: placeholders.PlaceholderForType,
+            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
+        self.index_phft = index_phft
 
     def check(self) -> CheckResult:
         exp_type = self.type3
@@ -451,7 +471,7 @@ class CanBeSubscriptedConstraint(ConstraintBase):
                 sa_type, sa_len = sa_args
 
                 result: List[ConstraintBase] = [
-                    SameTypeConstraint(prelude.u32, self.index_type3, comment='([]) :: Subscriptable a => a b -> u32 -> b'),
+                    SameTypeConstraint(prelude.u32, self.index_phft, comment='([]) :: Subscriptable a => a b -> u32 -> b'),
                     SameTypeConstraint(sa_type, self.ret_type3, comment='([]) :: Subscriptable a => a b -> u32 -> b'),
                 ]
 
@@ -478,13 +498,13 @@ class CanBeSubscriptedConstraint(ConstraintBase):
                     return Error('Tuple index out of range')
 
                 return [
-                    SameTypeConstraint(prelude.u32, self.index_type3, comment=f'Tuple subscript index {self.index.value}'),
+                    SameTypeConstraint(prelude.u32, self.index_phft, comment=f'Tuple subscript index {self.index.value}'),
                     SameTypeConstraint(tp_args[self.index.value], self.ret_type3, comment=f'Tuple subscript index {self.index.value}'),
                 ]
 
         if exp_type is prelude.bytes_:
             return [
-                SameTypeConstraint(prelude.u32, self.index_type3, comment='([]) :: bytes -> u32 -> u8'),
+                SameTypeConstraint(prelude.u32, self.index_phft, comment='([]) :: bytes -> u32 -> u8'),
                 SameTypeConstraint(prelude.u8, self.ret_type3, comment='([]) :: bytes -> u32 -> u8'),
             ]
 

phasm/type3/constraintsgenerator.py

@@ -19,6 +19,7 @@ from .constraints import (
     SameTypeConstraint,
     TupleMatchConstraint,
 )
+from .placeholders import PlaceholderForType
 
 ConstraintGenerator = Generator[ConstraintBase, None, None]
 
@@ -28,40 +29,50 @@ def phasm_type3_generate_constraints(inp: ourlang.Module) -> List[ConstraintBase
 
     return [*module(ctx, inp)]
 
-def constant(ctx: Context, inp: ourlang.Constant) -> ConstraintGenerator:
+def constant(ctx: Context, inp: ourlang.Constant, phft: placeholders.PlaceholderForType) -> ConstraintGenerator:
     if isinstance(inp, (ourlang.ConstantPrimitive, ourlang.ConstantBytes, ourlang.ConstantTuple, ourlang.ConstantStruct)):
         yield LiteralFitsConstraint(
-            inp.type3, inp,
+            phft, inp,
             comment='The given literal must fit the expected type'
         )
         return
 
     raise NotImplementedError(constant, inp)
 
-def expression(ctx: Context, inp: ourlang.Expression) -> ConstraintGenerator:
+def expression(ctx: Context, inp: ourlang.Expression, phft: placeholders.PlaceholderForType) -> ConstraintGenerator:
     if isinstance(inp, ourlang.Constant):
-        yield from constant(ctx, inp)
+        yield from constant(ctx, inp, phft)
         return
 
     if isinstance(inp, ourlang.VariableReference):
-        yield SameTypeConstraint(inp.variable.type3, inp.type3,
+        yield SameTypeConstraint(inp.variable.type3, phft,
             comment=f'typeOf("{inp.variable.name}") == typeOf({inp.variable.name})')
         return
 
     if isinstance(inp, ourlang.BinaryOp) or isinstance(inp, ourlang.FunctionCall):
-        signature = inp.operator.signature if isinstance(inp, ourlang.BinaryOp) else inp.function.signature
-        arguments = [inp.left, inp.right] if isinstance(inp, ourlang.BinaryOp) else inp.arguments
-
         func_name = f'({inp.operator.name})' if isinstance(inp, ourlang.BinaryOp) else inp.function.name
 
+        arguments = [inp.left, inp.right] if isinstance(inp, ourlang.BinaryOp) else inp.arguments
+
+        arg_placeholders = {
+            arg_expr: PlaceholderForType([arg_expr])
+            for arg_expr in arguments
+        }
+        arg_placeholders[inp] = phft
+
+        for call_arg in arguments:
+            yield from expression(ctx, call_arg, arg_placeholders[call_arg])
+
+        signature = inp.operator.signature if isinstance(inp, ourlang.BinaryOp) else inp.function.signature
         type_var_map = {
             x: placeholders.PlaceholderForType([])
             for x in signature.args
             if isinstance(x, functions.TypeVariable)
+            or isinstance(x, functions.TypeConstructorVariable)
         }
 
-        for call_arg in arguments:
-            yield from expression(ctx, call_arg)
+        for arg_expr in arguments:
+            yield from expression(ctx, arg_expr, arg_placeholders[arg_expr])
 
         for constraint in signature.context.constraints:
             if isinstance(constraint, functions.Constraint_TypeClassInstanceExists):
@@ -81,11 +92,11 @@ def expression(ctx: Context, inp: ourlang.Expression) -> ConstraintGenerator:
                 comment = f'The type of the value passed to argument {arg_no} of function {func_name} should match the type of that argument'
 
             if isinstance(sig_part, functions.TypeVariable):
-                yield SameTypeConstraint(type_var_map[sig_part], arg_expr.type3, comment=comment)
+                yield SameTypeConstraint(type_var_map[sig_part], arg_placeholders[arg_expr], comment=comment)
                 continue
 
             if isinstance(sig_part, type3types.Type3):
-                yield SameTypeConstraint(sig_part, arg_expr.type3, comment=comment)
+                yield SameTypeConstraint(sig_part, arg_placeholders[arg_expr], comment=comment)
                 continue
 
             raise NotImplementedError(sig_part)
@@ -94,11 +105,12 @@ def expression(ctx: Context, inp: ourlang.Expression) -> ConstraintGenerator:
     if isinstance(inp, ourlang.TupleInstantiation):
         r_type = []
         for arg in inp.elements:
-            yield from expression(ctx, arg)
-            r_type.append(arg.type3)
+            arg_phft = PlaceholderForType([arg])
+            yield from expression(ctx, arg, arg_phft)
+            r_type.append(arg_phft)
 
         yield TupleMatchConstraint(
-            inp.type3,
+            phft,
             r_type,
             comment='The type of a tuple is a combination of its members'
         )
@@ -106,10 +118,13 @@ def expression(ctx: Context, inp: ourlang.Expression) -> ConstraintGenerator:
         return
 
     if isinstance(inp, ourlang.Subscript):
-        yield from expression(ctx, inp.varref)
-        yield from expression(ctx, inp.index)
+        varref_phft = PlaceholderForType([inp.varref])
+        index_phft = PlaceholderForType([inp.index])
 
-        yield CanBeSubscriptedConstraint(inp.type3, inp.varref.type3, inp.index)
+        yield from expression(ctx, inp.varref, varref_phft)
+        yield from expression(ctx, inp.index, index_phft)
+
+        yield CanBeSubscriptedConstraint(phft, varref_phft, inp.index, index_phft)
         return
 
     if isinstance(inp, ourlang.AccessStructMember):
@@ -117,33 +132,40 @@ def expression(ctx: Context, inp: ourlang.Expression) -> ConstraintGenerator:
         st_args = prelude.struct.did_construct(inp.struct_type3)
         assert st_args is not None  # FIXME: See test_struct.py::test_struct_not_accessible
 
-        yield from expression(ctx, inp.varref)
-        yield SameTypeConstraint(st_args[inp.member], inp.type3,
+        yield from expression(ctx, inp.varref, PlaceholderForType([inp.varref]))  # TODO
+        yield SameTypeConstraint(st_args[inp.member], phft,
             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)
+        base_phft = PlaceholderForType([inp.base])
+        iter_phft = PlaceholderForType([inp.iter])
 
-        yield SameTypeConstraint(inp.func.posonlyargs[0].type3, inp.func.returns_type3, inp.base.type3, inp.type3,
+        yield from expression(ctx, inp.base, base_phft)
+        yield from expression(ctx, inp.iter, iter_phft)
+
+        yield SameTypeConstraint(inp.func.posonlyargs[0].type3, inp.func.returns_type3, base_phft, phft,
             comment='foldl :: Foldable t => (b -> a -> b) -> b -> t a -> b')
-        yield MustImplementTypeClassConstraint(ctx, 'Foldable', [inp.iter.type3])
+        yield MustImplementTypeClassConstraint(ctx, 'Foldable', [iter_phft])
 
         return
 
     raise NotImplementedError(expression, inp)
 
 def statement_return(ctx: Context, fun: ourlang.Function, inp: ourlang.StatementReturn) -> ConstraintGenerator:
-    yield from expression(ctx, inp.value)
+    phft = PlaceholderForType([inp.value])
 
-    yield SameTypeConstraint(fun.returns_type3, inp.value.type3,
+    yield from expression(ctx, inp.value, phft)
+
+    yield SameTypeConstraint(fun.returns_type3, phft,
         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)
+    test_phft = PlaceholderForType([inp.test])
 
-    yield SameTypeConstraint(inp.test.type3, prelude.bool_,
+    yield from expression(ctx, inp.test, test_phft)
+
+    yield SameTypeConstraint(test_phft, prelude.bool_,
         comment='Must pass a boolean expression to if')
 
     for stmt in inp.statements:
@@ -173,8 +195,10 @@ def function(ctx: Context, inp: ourlang.Function) -> ConstraintGenerator:
         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,
+    phft = PlaceholderForType([inp.constant])
+
+    yield from constant(ctx, inp.constant, phft)
+    yield SameTypeConstraint(inp.type3, phft,
         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:

phasm/type3/entry.py

@@ -115,8 +115,6 @@ def phasm_type3(inp: ourlang.Module, verbose: bool = False) -> None:
     # 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:

phasm/type3/functions.py

@@ -34,6 +34,25 @@ class TypeVariable:
     def __repr__(self) -> str:
         return f'TypeVariable({repr(self.letter)})'
 
+class TypeConstructorVariable:
+    """
+    Types constructor variable are used in function definition.
+
+    They are a lot like TypeVariable, except that they represent a
+    type constructor rather than a type directly.
+    """
+    __slots__ = ('letter', 'args', )
+
+    def __init__(self, letter: str, args: Iterable[TypeVariable]) -> None:
+        self.letter = letter
+        self.args = list(args)
+
+    def __call__(self, tvar: TypeVariable) -> 'TypeConstructorVariable':
+        return TypeConstructorVariable(self.letter, self.args + [tvar])
+
+    def __repr__(self) -> str:
+        return f'TypeConstructorVariable({self.letter!r}, {self.args!r})'
+
 class ConstraintBase:
     __slots__ = ()
 
@@ -41,9 +60,9 @@ class Constraint_TypeClassInstanceExists(ConstraintBase):
     __slots__ = ('type_class3', 'types', )
 
     type_class3: 'Type3Class'
-    types: list[TypeVariable]
+    types: list[Union[TypeVariable, TypeConstructorVariable]]
 
-    def __init__(self, type_class3: 'Type3Class', types: Iterable[TypeVariable]) -> None:
+    def __init__(self, type_class3: 'Type3Class', types: Iterable[Union[TypeVariable, TypeConstructorVariable]]) -> None:
         self.type_class3 = type_class3
         self.types = list(types)
 
@@ -52,27 +71,22 @@ class Constraint_TypeClassInstanceExists(ConstraintBase):
         assert len(self.type_class3.args) == len(self.types)
 
 class TypeVariableContext:
-    __slots__ = ('variables', 'constraints', )
+    __slots__ = ('constraints', )
 
-    variables: set[TypeVariable]
     constraints: list[ConstraintBase]
 
-    def __init__(self) -> None:
-        self.variables = set()
-        self.constraints = []
+    def __init__(self, constraints: Iterable[ConstraintBase] = ()) -> None:
+        self.constraints = list(constraints)
 
     def __copy__(self) -> 'TypeVariableContext':
-        result = TypeVariableContext()
-        result.variables.update(self.variables)
-        result.constraints.extend(self.constraints)
-        return result
+        return TypeVariableContext(self.constraints)
 
 class FunctionSignature:
     __slots__ = ('context', 'args', )
 
     context: TypeVariableContext
-    args: List[Union['Type3', TypeVariable]]
+    args: List[Union['Type3', TypeVariable, TypeConstructorVariable]]
 
-    def __init__(self, context: TypeVariableContext, args: Iterable[Union['Type3', TypeVariable]]) -> None:
+    def __init__(self, context: TypeVariableContext, args: Iterable[Union['Type3', TypeVariable, TypeConstructorVariable]]) -> None:
         self.context = context.__copy__()
         self.args = list(args)

phasm/type3/placeholders.py

@@ -7,14 +7,13 @@ from typing import Any, Iterable, List, Optional, Protocol, Union
 
 from .types import Type3
 
-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'
+    type3: Type3 | None
     """
     The type to update
     """

phasm/type3/typeclasses.py

@@ -2,7 +2,9 @@ from typing import Dict, Iterable, List, Mapping, Optional, Union
 
 from .functions import (
     Constraint_TypeClassInstanceExists,
+    ConstraintBase,
     FunctionSignature,
+    TypeConstructorVariable,
     TypeVariable,
     TypeVariableContext,
 )
@@ -26,7 +28,7 @@ class Type3Class:
     __slots__ = ('name', 'args', 'methods', 'operators', 'inherited_classes', )
 
     name: str
-    args: List[TypeVariable]
+    args: List[Union[TypeVariable, TypeConstructorVariable]]
     methods: Dict[str, Type3ClassMethod]
     operators: Dict[str, Type3ClassMethod]
     inherited_classes: List['Type3Class']
@@ -34,10 +36,11 @@ class Type3Class:
     def __init__(
             self,
             name: str,
-            args: Iterable[TypeVariable],
-            methods: Mapping[str, Iterable[Union[Type3, TypeVariable]]],
-            operators: Mapping[str, Iterable[Union[Type3, TypeVariable]]],
+            args: Iterable[Union[TypeVariable, TypeConstructorVariable]],
+            methods: Mapping[str, Iterable[Union[Type3, TypeVariable, TypeConstructorVariable]]],
+            operators: Mapping[str, Iterable[Union[Type3, TypeVariable, TypeConstructorVariable]]],
             inherited_classes: Optional[List['Type3Class']] = None,
+            additional_context: Optional[Mapping[str, Iterable[ConstraintBase]]] = None,
         ) -> None:
         self.name = name
         self.args = list(args)
@@ -55,5 +58,12 @@ class Type3Class:
         }
         self.inherited_classes = inherited_classes or []
 
+        if additional_context:
+            for func_name, constraint_list in additional_context.items():
+                func = self.methods.get(func_name) or self.operators.get(func_name)
+                assert func is not None  # type hint
+
+                func.signature.context.constraints.extend(constraint_list)
+
     def __repr__(self) -> str:
         return self.name

phasm/type3/types.py

@@ -106,7 +106,7 @@ class TypeConstructor(Generic[T]):
     The name of the type constructor
     """
 
-    on_create: Callable[[Type3], None]
+    on_create: Callable[[T, Type3], None]
     """
     Who to let know if a type is created
     """
@@ -122,7 +122,7 @@ class TypeConstructor(Generic[T]):
     Sometimes we need to know the key that created a type.
     """
 
-    def __init__(self, name: str, on_create: Callable[[Type3], None]) -> None:
+    def __init__(self, name: str, on_create: Callable[[T, Type3], None]) -> None:
         self.name = name
         self.on_create = on_create
 
@@ -152,7 +152,7 @@ class TypeConstructor(Generic[T]):
         if result is None:
             self._cache[key] = result = Type3(self.make_name(key))
             self._reverse_cache[result] = key
-            self.on_create(result)
+            self.on_create(key, result)
 
         return result
 

tests/integration/helpers.py

@@ -5,7 +5,6 @@ from typing import Any, Generator, Iterable, List, TextIO, Union
 from phasm import compiler, prelude
 from phasm.codestyle import phasm_render
 from phasm.runtime import calculate_alloc_size
-from phasm.type3 import placeholders as type3placeholders
 from phasm.type3 import types as type3types
 
 from . import runners
@@ -65,9 +64,6 @@ class Suite:
             runner.interpreter_dump_memory(sys.stderr)
 
             for arg, arg_typ in zip(args, func_args, strict=True):
-                assert not isinstance(arg_typ, type3placeholders.PlaceholderForType), \
-                    'Cannot call polymorphic function from outside'
-
                 if arg_typ in (prelude.u8, prelude.u32, prelude.u64, ):
                     assert isinstance(arg, int)
                     wasm_args.append(arg)
@@ -88,7 +84,6 @@ class Suite:
                     wasm_args.append(adr)
                     continue
 
-                assert isinstance(arg_typ, type3types.Type3)
                 sa_args = prelude.static_array.did_construct(arg_typ)
                 if sa_args is not None:
                         adr = _allocate_memory_stored_value(runner, arg_typ, arg)
@@ -222,8 +217,6 @@ def _allocate_memory_stored_value(
 
             offset = adr
             for val_el_val, val_el_typ in zip(val, tp_args, strict=True):
-                assert not isinstance(val_el_typ, type3placeholders.PlaceholderForType)
-
                 offset += _write_memory_stored_value(runner, offset, val_el_typ, val_el_val)
             return adr
 
@@ -240,8 +233,6 @@ def _allocate_memory_stored_value(
 
         offset = adr
         for val_el_name, val_el_typ in st_args.items():
-            assert not isinstance(val_el_typ, type3placeholders.PlaceholderForType)
-
             val_el_val = val[val_el_name]
             offset += _write_memory_stored_value(runner, offset, val_el_typ, val_el_val)
         return adr
@@ -299,8 +290,6 @@ def _load_memory_stored_returned_value(
 
         return _load_bytes_from_address(runner, ret_type3, wasm_value)
 
-    assert isinstance(ret_type3, type3types.Type3) # Type hint
-
     sa_args = prelude.static_array.did_construct(ret_type3)
     if sa_args is not None:
             assert isinstance(wasm_value, int), wasm_value
@@ -366,8 +355,6 @@ def _unpack(runner: runners.RunnerBase, typ: type3types.Type3, inp: bytes) -> An
         assert len(inp) == 4
         adr = struct.unpack('<I', inp)[0]
 
-        assert isinstance(typ, type3types.Type3)
-
         sa_args = prelude.static_array.did_construct(typ)
         if sa_args is not None:
             sa_type, sa_len = sa_args
@@ -404,9 +391,6 @@ def _split_read_bytes(all_bytes: bytes, split_sizes: Iterable[int]) -> Generator
 def _load_static_array_from_address(runner: runners.RunnerBase, sub_typ: type3types.Type3, len_typ: type3types.IntType3, adr: int) -> Any:
     sys.stderr.write(f'Reading 0x{adr:08x} {sub_typ:s} {len_typ:s}\n')
 
-    assert not isinstance(sub_typ, type3placeholders.PlaceholderForType)
-    assert isinstance(len_typ, type3types.IntType3)
-
     sa_len = len_typ.value
 
     arg_size_1 = calculate_alloc_size(sub_typ, is_member=True)

tests/integration/test_lang/test_foldable.py

@@ -0,0 +1,55 @@
+import pytest
+
+from phasm.type3.entry import Type3Exception
+
+from ..helpers import Suite
+
+
+@pytest.mark.integration_test
+def test_foldable_sum():
+    code_py = """
+@exported
+def testEntry(x: i32[5]) -> i32:
+    return sum(x)
+"""
+
+    result = Suite(code_py).run_code((4, 5, 6, 7, 8, ))
+
+    assert 30 == result.returned_value
+
+@pytest.mark.integration_test
+def test_foldable_sum_not_natnum():
+    code_py = """
+class Foo:
+    bar: i32
+
+@exported
+def testEntry(x: Foo[4]) -> Foo:
+    return sum(x)
+"""
+
+    with pytest.raises(Type3Exception, match='Missing type class instantation: NatNum Foo'):
+        Suite(code_py).run_code()
+
+
+@pytest.mark.integration_test
+def test_foldable_invalid_return_type():
+    code_py = """
+@exported
+def testEntry(x: i32[5]) -> f64:
+    return sum(x)
+"""
+
+    with pytest.raises(Type3Exception, match='f64 must be i32 instead'):
+        Suite(code_py).run_code((4, 5, 6, 7, 8, ))
+
+@pytest.mark.integration_test
+def test_foldable_not_foldable():
+    code_py = """
+@exported
+def testEntry(x: i32) -> i32:
+    return sum(x)
+"""
+
+    with pytest.raises(Type3Exception, match='Missing type class instantation: Foldable i32'):
+        Suite(code_py).run_code()

tests/integration/test_lang/test_literals.py

@@ -6,7 +6,20 @@ from ..helpers import Suite
 
 
 @pytest.mark.integration_test
-def test_expr_constant_literal_does_not_fit():
+def test_expr_constant_literal_does_not_fit_module_constant():
+    code_py = """
+CONSTANT: u8 = 1000
+
+@exported
+def testEntry() -> u8:
+    return CONSTANT
+"""
+
+    with pytest.raises(Type3Exception, match=r'Must fit in 1 byte\(s\)'):
+        Suite(code_py).run_code()
+
+@pytest.mark.integration_test
+def test_expr_constant_literal_does_not_fit_return():
     code_py = """
 @exported
 def testEntry() -> u8: