phasm/codestyle.py

@@ -97,6 +97,9 @@ def expression(inp: ourlang.Expression) -> str:
             or inp.operator in ourlang.WEBASSEMBLY_BUILDIN_BYTES_OPS):
             return f'{inp.operator}({expression(inp.right)})'
 
+        if inp.operator == 'cast':
+            return f'{type_(inp.type)}({expression(inp.right)})'
+
         return f'{inp.operator}{expression(inp.right)}'
 
     if isinstance(inp, ourlang.BinaryOp):

phasm/compiler.py

@@ -219,6 +219,11 @@ def expression(wgn: WasmGenerator, inp: ourlang.Expression) -> None:
                     wgn.i32.load()
                     return
 
+        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
+                return
+
         raise NotImplementedError(expression, inp.type, inp.operator)
 
     if isinstance(inp, ourlang.FunctionCall):

phasm/parser.py

@@ -380,6 +380,20 @@ class OurVisitor:
                 'sqrt',
                 self.visit_Module_FunctionDef_expr(module, function, our_locals, exp_type, 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]),
+            )
         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}')
@@ -398,14 +412,9 @@ class OurVisitor:
             # 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 not isinstance(exp_type, TypeUInt8):
-                _raise_static_error(node, f'Cannot make {node.func.id} result in {exp_type} - not implemented yet')
-
             if 3 != len(node.args):
                 _raise_static_error(node, f'Function {node.func.id} requires 3 arguments but {len(node.args)} are given')
 
-            t_u8 = module.types['u8']
-
             # TODO: This is not generic
             subnode = node.args[0]
             if not isinstance(subnode, ast.Name):
@@ -415,6 +424,19 @@ class OurVisitor:
             if subnode.id not in module.functions:
                 _raise_static_error(subnode, 'Reference to undefined function')
             func = module.functions[subnode.id]
+            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])}')
+
+            t_u8 = module.types['u8']
+
+            if t_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,

tests/integration/test_builtins.py

@@ -63,3 +63,18 @@ def testEntry(a: bytes, b: bytes) -> u8:
 
     result = suite.run_code(b'\x55\x0F', b'\x33\x80')
     assert 233 == result.returned_value
+
+@pytest.mark.integration_test
+def test_foldl_3():
+    code_py = """
+def xor(l: u32, r: u8) -> u32:
+    return l ^ u32(r)
+
+@exported
+def testEntry(a: bytes) -> u32:
+    return foldl(xor, 0, a)
+"""
+    suite = Suite(code_py)
+
+    result = suite.run_code(b'\x55\x0F\x33\x80')
+    assert 233 == result.returned_value