diff --git a/phasm/compiler.py b/phasm/compiler.py
index 103f580..71ee949 100644
--- a/phasm/compiler.py
+++ b/phasm/compiler.py
@@ -63,6 +63,11 @@ def type3(inp: type3types.Type3OrPlaceholder) -> wasm.WasmType:
     if inp is type3types.f64:
         return wasm.WasmTypeFloat64()
 
+    if inp is type3types.bytes:
+        # bytes are passed as pointer
+        # And pointers are i32
+        return wasm.WasmTypeInt32()
+
     if isinstance(inp, type3types.StructType3):
         # Structs and tuples are passed as pointer
         # And pointers are i32
@@ -273,13 +278,13 @@ def expression(wgn: WasmGenerator, inp: ourlang.Expression) -> None:
                 wgn.add_statement(f'f64.{inp.operator}')
                 return
 
-        # TODO: Broken after new type system
-        # if isinstance(inp.type, typing.TypeInt32):
-        #     if inp.operator == 'len':
-        #         if isinstance(inp.right.type, typing.TypeBytes):
-        #             wgn.i32.load()
-        #             return
+        if inp.type3 is type3types.u32:
+            if inp.operator == 'len':
+                if inp.right.type3 is type3types.bytes:
+                    wgn.i32.load()
+                    return
 
+        # TODO: Broken after new type system
         # if inp.operator == 'cast':
         #     if isinstance(inp.type, typing.TypeUInt32) and isinstance(inp.right.type, typing.TypeUInt8):
         #         # Nothing to do, you can use an u8 value as a u32 no problem
diff --git a/phasm/type3/constraints.py b/phasm/type3/constraints.py
index 4f66018..c097771 100644
--- a/phasm/type3/constraints.py
+++ b/phasm/type3/constraints.py
@@ -154,6 +154,17 @@ class MustImplementTypeClassConstraint(ConstraintBase):
     type_class3: str
     type3: types.Type3OrPlaceholder
 
+    DATA = {
+        'u8': {'BitWiseOperation', 'BasicMathOperation'},
+        'u32': {'BitWiseOperation', 'BasicMathOperation'},
+        'u64': {'BitWiseOperation', 'BasicMathOperation'},
+        'i32': {'BasicMathOperation'},
+        'i64': {'BasicMathOperation'},
+        'bytes': {'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)
 
@@ -168,14 +179,7 @@ class MustImplementTypeClassConstraint(ConstraintBase):
         if isinstance(typ, types.PlaceholderForType):
             return RequireTypeSubstitutes()
 
-        if 'BitWiseOperation' == self.type_class3 and (typ is types.u8 or typ is types.u32 or typ is types.u64):
-            return None
-
-        if 'BasicMathOperation' == self.type_class3 and (
-                typ is types.u8 or typ is types.u32 or typ is types.u64
-                or typ is types.i32 or typ is types.i64
-                or typ is types.f32 or typ is types.f64
-            ):
+        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')
diff --git a/phasm/type3/constraintsgenerator.py b/phasm/type3/constraintsgenerator.py
index 1adb51b..2878bd1 100644
--- a/phasm/type3/constraintsgenerator.py
+++ b/phasm/type3/constraintsgenerator.py
@@ -15,6 +15,8 @@ from .constraints import (
     LiteralFitsConstraint, MustImplementTypeClassConstraint, SameTypeConstraint,
 )
 
+from . import types as type3types
+
 def phasm_type3_generate_constraints(inp: ourlang.Module) -> List[ConstraintBase]:
     ctx = Context()
 
@@ -37,6 +39,21 @@ def expression(ctx: Context, inp: ourlang.Expression) -> Generator[ConstraintBas
             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
+
+        raise NotImplementedError(expression, inp, inp.operator)
+
     if isinstance(inp, ourlang.BinaryOp):
         if inp.operator in ('|', '&', '^', ):
             yield from expression(ctx, inp.left)
@@ -47,6 +64,17 @@ def expression(ctx: Context, inp: ourlang.Expression) -> Generator[ConstraintBas
                 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.type3,
+                comment=f'({inp.operator}) :: a -> u64 -> a')
+            yield SameTypeConstraint(type3types.u64, inp.right.type3,
+                comment=f'({inp.operator}) :: a -> u64 -> a')
+            return
+
         if inp.operator in ('+', '-', '*', '/', ):
             yield from expression(ctx, inp.left)
             yield from expression(ctx, inp.right)
diff --git a/phasm/type3/entry.py b/phasm/type3/entry.py
index 8f77634..c1b68e3 100644
--- a/phasm/type3/entry.py
+++ b/phasm/type3/entry.py
@@ -76,6 +76,9 @@ def phasm_type3(inp: ourlang.Module, verbose: bool = False) -> None:
         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
diff --git a/phasm/type3/types.py b/phasm/type3/types.py
index 7ff91e1..a91cab1 100644
--- a/phasm/type3/types.py
+++ b/phasm/type3/types.py
@@ -215,6 +215,11 @@ f64 = Type3('f64')
 A 32-bits IEEE 754 float, of 64 bits width.
 """
 
+bytes = Type3('bytes')
+"""
+This is a runtime-determined length piece of memory that can be indexed at runtime.
+"""
+
 static_array = Type3('static_array')
 """
 This is a fixed length piece of memory that can be indexed at runtime.
@@ -241,4 +246,5 @@ LOOKUP_TABLE: Dict[str, Type3] = {
     'i64': i64,
     'f32': f32,
     'f64': f64,
+    'bytes': bytes,
 }
diff --git a/tests/integration/test_lang/test_bytes.py b/tests/integration/test_lang/test_bytes.py
index 45fc2a1..6df111a 100644
--- a/tests/integration/test_lang/test_bytes.py
+++ b/tests/integration/test_lang/test_bytes.py
@@ -20,13 +20,13 @@ def testEntry(f: bytes) -> bytes:
 def test_bytes_length():
     code_py = """
 @exported
-def testEntry(f: bytes) -> i32:
+def testEntry(f: bytes) -> u32:
     return len(f)
 """
 
-    result = Suite(code_py).run_code(b'This is another test')
+    result = Suite(code_py).run_code(b'This yet is another test')
 
-    assert 20 == result.returned_value
+    assert 24 == result.returned_value
 
 @pytest.mark.integration_test
 def test_bytes_index():
diff --git a/tests/integration/test_lang/test_primitives.py b/tests/integration/test_lang/test_primitives.py
index ff2db0c..640a898 100644
--- a/tests/integration/test_lang/test_primitives.py
+++ b/tests/integration/test_lang/test_primitives.py
@@ -468,7 +468,7 @@ def testEntry() -> i32:
     return helper()
 """
 
-    with pytest.raises(Type3Exception, match=r'i32.*i64'):
+    with pytest.raises(Type3Exception, match=r'i64 must be i32 instead'):
         Suite(code_py).run_code()
 
 @pytest.mark.integration_test
diff --git a/tests/integration/test_lang/test_struct.py b/tests/integration/test_lang/test_struct.py
index 35663c4..bb70323 100644
--- a/tests/integration/test_lang/test_struct.py
+++ b/tests/integration/test_lang/test_struct.py
@@ -99,5 +99,5 @@ def testEntry(arg: Struct) -> (i32, i32, ):
     return arg.param
 """
 
-    with pytest.raises(Type3Exception, match=r'\(i32, i32, \) must be ' + type_ + ' instead'):
+    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
index fd74a72..a08b382 100644
--- a/tests/integration/test_lang/test_tuple.py
+++ b/tests/integration/test_lang/test_tuple.py
@@ -112,7 +112,7 @@ def test_tuple_constant_type_mismatch():
 CONSTANT: (u32, u8, u8, ) = (24, 4000, 1, )
 """
 
-    with pytest.raises(Type3Exception, match='Must fit in 1 byte(s)'):
+    with pytest.raises(Type3Exception, match=r'Must fit in 1 byte\(s\)'):
         Suite(code_py).run_code()
 
 @pytest.mark.integration_test