Reimplements casting and foldl

Probably not 100% type checked yet.

Also, fixed logical right shift; standard says the type
is different.

phasm/compiler.py

@@ -297,11 +297,10 @@ def expression(wgn: WasmGenerator, inp: ourlang.Expression) -> None:
                     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
-        #         return
+        if inp.operator == 'cast':
+            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.type3, inp.operator)
 
@@ -397,10 +396,8 @@ def expression_fold(wgn: WasmGenerator, inp: ourlang.Fold) -> None:
     """
     assert isinstance(inp.type3, type3types.Type3), type3types.TYPE3_ASSERTION_ERROR
 
-    raise NotImplementedError('TODO: Broken after new type system')
-
-    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.type3(inp.type3)}_acu')

phasm/parser.py

@@ -563,8 +563,6 @@ 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')
 
-            raise NotImplementedError('TODO: Broken after new type system')
-
             return Fold(
                 Fold.Direction.LEFT,
                 func,

phasm/type3/constraints.py

@@ -147,6 +147,50 @@ class SameTypeConstraint(ConstraintBase):
 
         return f'SameTypeConstraint({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, smap: SubstitutionMap) -> CheckResult:
+        ftyp = self.from_type3
+        if isinstance(ftyp, types.PlaceholderForType) and ftyp in smap:
+            ftyp = smap[ftyp]
+
+        ttyp = self.to_type3
+        if isinstance(ttyp, types.PlaceholderForType) and ttyp in smap:
+            ttyp = smap[ttyp]
+
+        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
@@ -162,7 +206,7 @@ class MustImplementTypeClassConstraint(ConstraintBase):
         'u64': {'BitWiseOperation', 'BasicMathOperation'},
         'i32': {'BasicMathOperation'},
         'i64': {'BasicMathOperation'},
-        'bytes': {'Sized'},
+        'bytes': {'Foldable', 'Sized'},
         'f32': {'BasicMathOperation', 'FloatingPoint'},
         'f64': {'BasicMathOperation', 'FloatingPoint'},
     }

phasm/type3/constraintsgenerator.py

@@ -11,7 +11,7 @@ from .constraints import (
     Context,
 
     ConstraintBase,
-    CanBeSubscriptedConstraint,
+    CastableConstraint, CanBeSubscriptedConstraint,
     LiteralFitsConstraint, MustImplementTypeClassConstraint, SameTypeConstraint,
 )
 
@@ -52,6 +52,11 @@ def expression(ctx: Context, inp: ourlang.Expression) -> Generator[ConstraintBas
             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):
@@ -69,10 +74,8 @@ def expression(ctx: Context, inp: ourlang.Expression) -> Generator[ConstraintBas
             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')
+            yield SameTypeConstraint(inp.left.type3, inp.right.type3, inp.type3,
+                comment=f'({inp.operator}) :: a -> a -> a')
             return
 
         if inp.operator in ('+', '-', '*', '/', ):
@@ -112,6 +115,16 @@ def expression(ctx: Context, inp: ourlang.Expression) -> Generator[ConstraintBas
             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 function(ctx: Context, inp: ourlang.Function) -> Generator[ConstraintBase, None, None]:

tests/integration/test_lang/test_primitives.py

@@ -111,7 +111,9 @@ def testEntry() -> {type_}:
     return 10 >> 3
 """
 
-    result = Suite(code_py).run_code()
+    # 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)