First attempt at ripping out old system

This breaks test_addition[u32], which is a good thing to chase next.

phasm/codestyle.py

@@ -86,14 +86,8 @@ 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)
 
@@ -104,7 +98,7 @@ def expression(inp: ourlang.Expression) -> str:
         ) + ', )'
 
     if isinstance(inp, ourlang.VariableReference):
-        return str(inp.name)
+        return str(inp.variable.name)
 
     if isinstance(inp, ourlang.UnaryOp):
         if (
@@ -193,8 +187,8 @@ def function(inp: ourlang.Function) -> str:
         result += '@imported\n'
 
     args = ', '.join(
-        f'{x}: {type_(y)}'
-        for x, y in inp.posonlyargs
+        f'{p.name}: {type_(p.type)}'
+        for p in inp.posonlyargs
     )
 
     result += f'def {inp.name}({args}) -> {type_(inp.returns)}:\n'

phasm/compiler.py

@@ -131,36 +131,28 @@ 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):
+        stp = typing.simplify(inp.type_var)
+        if stp is None:
+            raise NotImplementedError(f'Constants with type {inp.type_var}')
 
-    if isinstance(inp, ourlang.ConstantUInt32):
-        wgn.i32.const(inp.value)
-        return
+        if stp == 'u8':
+            # No native u8 type - treat as i32, with caution
+            wgn.i32.const(inp.value)
+            return
 
-    if isinstance(inp, ourlang.ConstantUInt64):
-        wgn.i64.const(inp.value)
-        return
+        if stp in ('i32', 'u32'):
+            wgn.i32.const(inp.value)
+            return
 
-    if isinstance(inp, ourlang.ConstantInt32):
-        wgn.i32.const(inp.value)
-        return
+        if stp in ('i64', 'u64'):
+            wgn.i64.const(inp.value)
+            return
 
-    if isinstance(inp, ourlang.ConstantInt64):
-        wgn.i64.const(inp.value)
-        return
-
-    if isinstance(inp, ourlang.ConstantFloat32):
-        wgn.f32.const(inp.value)
-        return
-
-    if isinstance(inp, ourlang.ConstantFloat64):
-        wgn.f64.const(inp.value)
-        return
+        raise NotImplementedError(f'Constants with type {stp}')
 
     if isinstance(inp, ourlang.VariableReference):
-        wgn.add_statement('local.get', '${}'.format(inp.name))
+        wgn.add_statement('local.get', '${}'.format(inp.variable.name))
         return
 
     if isinstance(inp, ourlang.BinaryOp):
@@ -450,7 +442,7 @@ def function_argument(inp: ourlang.FunctionParam) -> wasm.Param:
     """
     Compile: function argument
     """
-    return (inp[0], type_(inp[1]), )
+    return (inp.name, type_(inp.type), )
 
 def import_(inp: ourlang.Function) -> wasm.Import:
     """

phasm/exceptions.py

@@ -6,3 +6,6 @@ class StaticError(Exception):
     """
     An error found during static analysis
     """
+
+class TypingError(Exception):
+    pass

phasm/ourlang.py

@@ -21,18 +21,22 @@ from .typing import (
     TypeTuple, TypeTupleMember,
     TypeStaticArray, TypeStaticArrayMember,
     TypeStruct, TypeStructMember,
+
+    TypeVar,
 )
 
 class Expression:
     """
     An expression within a statement
     """
-    __slots__ = ('type', )
+    __slots__ = ('type', 'type_var', )
 
     type: TypeBase
+    type_var: Optional[TypeVar]
 
     def __init__(self, type_: TypeBase) -> None:
         self.type = type_
+        self.type_var = None
 
 class Constant(Expression):
     """
@@ -40,88 +44,15 @@ class Constant(Expression):
     """
     __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_)
-        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_)
+    def __init__(self, value: Union[int, float]) -> None:
         self.value = value
 
 class ConstantTuple(Constant):
@@ -130,9 +61,9 @@ class ConstantTuple(Constant):
     """
     __slots__ = ('value', )
 
-    value: List[Constant]
+    value: List[ConstantPrimitive]
 
-    def __init__(self, type_: TypeTuple, value: List[Constant]) -> None:
+    def __init__(self, type_: TypeTuple, value: List[ConstantPrimitive]) -> None: # FIXME: Tuple of tuples?
         super().__init__(type_)
         self.value = value
 
@@ -142,9 +73,9 @@ class ConstantStaticArray(Constant):
     """
     __slots__ = ('value', )
 
-    value: List[Constant]
+    value: List[ConstantPrimitive]
 
-    def __init__(self, type_: TypeStaticArray, value: List[Constant]) -> None:
+    def __init__(self, type_: TypeStaticArray, value: List[ConstantPrimitive]) -> None: # FIXME: Arrays of arrays?
         super().__init__(type_)
         self.value = value
 
@@ -152,13 +83,13 @@ class VariableReference(Expression):
     """
     An variable reference expression within a statement
     """
-    __slots__ = ('name', )
+    __slots__ = ('variable', )
 
-    name: str
+    variable: 'FunctionParam' # also possibly local
 
-    def __init__(self, type_: TypeBase, name: str) -> None:
+    def __init__(self, type_: TypeBase, variable: 'FunctionParam') -> None:
         super().__init__(type_)
-        self.name = name
+        self.variable = variable
 
 class UnaryOp(Expression):
     """
@@ -348,13 +279,23 @@ class StatementIf(Statement):
         self.statements = []
         self.else_statements = []
 
-FunctionParam = Tuple[str, TypeBase]
+class FunctionParam:
+    __slots__ = ('name', 'type', 'type_var', )
+
+    name: str
+    type: TypeBase
+    type_var: Optional[TypeVar]
+
+    def __init__(self, name: str, type_: TypeBase) -> None:
+        self.name = name
+        self.type = type_
+        self.type_var = None
 
 class Function:
     """
     A function processes input and produces output
     """
-    __slots__ = ('name', 'lineno', 'exported', 'imported', 'statements', 'returns', 'posonlyargs', )
+    __slots__ = ('name', 'lineno', 'exported', 'imported', 'statements', 'returns', 'returns_type_var', 'posonlyargs', )
 
     name: str
     lineno: int
@@ -362,6 +303,7 @@ class Function:
     imported: bool
     statements: List[Statement]
     returns: TypeBase
+    returns_type_var: Optional[TypeVar]
     posonlyargs: List[FunctionParam]
 
     def __init__(self, name: str, lineno: int) -> None:
@@ -371,6 +313,7 @@ class Function:
         self.imported = False
         self.statements = []
         self.returns = TypeNone()
+        self.returns_type_var = None
         self.posonlyargs = []
 
 class StructConstructor(Function):
@@ -390,7 +333,7 @@ class StructConstructor(Function):
         self.returns = struct
 
         for mem in struct.members:
-            self.posonlyargs.append((mem.name, mem.type, ))
+            self.posonlyargs.append(FunctionParam(mem.name, mem.type, ))
 
         self.struct = struct
 
@@ -410,7 +353,7 @@ class TupleConstructor(Function):
         self.returns = tuple_
 
         for mem in tuple_.members:
-            self.posonlyargs.append((f'arg{mem.idx}', mem.type, ))
+            self.posonlyargs.append(FunctionParam(f'arg{mem.idx}', mem.type, ))
 
         self.tuple = tuple_
 
@@ -439,10 +382,10 @@ 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
 

phasm/parser.py

@@ -35,9 +35,7 @@ from .ourlang import (
     AccessBytesIndex, AccessStructMember, AccessTupleMember, AccessStaticArrayMember,
     BinaryOp,
     Constant,
-    ConstantFloat32, ConstantFloat64, ConstantInt32, ConstantInt64,
-    ConstantUInt8, ConstantUInt32, ConstantUInt64,
-    ConstantTuple, ConstantStaticArray,
+    ConstantPrimitive, ConstantTuple, ConstantStaticArray,
 
     FunctionCall,
     StructConstructor, TupleConstructor,
@@ -48,6 +46,7 @@ from .ourlang import (
     Statement,
     StatementIf, StatementPass, StatementReturn,
 
+    FunctionParam,
     ModuleConstantDef,
 )
 
@@ -60,7 +59,7 @@ def phasm_parse(source: str) -> Module:
     our_visitor = OurVisitor()
     return our_visitor.visit_Module(res)
 
-OurLocals = Dict[str, TypeBase]
+OurLocals = Dict[str, Union[FunctionParam]] # Also local variable and module constants?
 
 class OurVisitor:
     """
@@ -141,7 +140,7 @@ class OurVisitor:
             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),
             ))
@@ -210,18 +209,14 @@ class OurVisitor:
 
         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):
+            return ModuleConstantDef(
                 node.target.id,
                 node.lineno,
                 exp_type,
-                self.visit_Module_Constant(module, exp_type, node.value),
+                self.visit_Module_Constant(module, node.value),
                 None,
             )
-            return constant
 
         if isinstance(exp_type, TypeTuple):
             if not isinstance(node.value, ast.Tuple):
@@ -231,7 +226,7 @@ class OurVisitor:
                 _raise_static_error(node, 'Invalid number of tuple values')
 
             tuple_data = [
-                self.visit_Module_Constant(module, mem.type, arg_node)
+                self.visit_Module_Constant(module, arg_node)
                 for arg_node, mem in zip(node.value.elts, exp_type.members)
                 if isinstance(arg_node, ast.Constant)
             ]
@@ -259,7 +254,7 @@ class OurVisitor:
                 _raise_static_error(node, 'Invalid number of static array values')
 
             static_array_data = [
-                self.visit_Module_Constant(module, exp_type.member_type, arg_node)
+                self.visit_Module_Constant(module, arg_node)
                 for arg_node in node.value.elts
                 if isinstance(arg_node, ast.Constant)
             ]
@@ -297,7 +292,10 @@ 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(
@@ -409,7 +407,7 @@ class OurVisitor:
 
         if isinstance(node, ast.Constant):
             return self.visit_Module_Constant(
-                module, exp_type, node,
+                module, node,
             )
 
         if isinstance(node, ast.Attribute):
@@ -427,11 +425,11 @@ 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)}')
+                param = our_locals[node.id]
+                if exp_type != param.type:
+                    _raise_static_error(node, f'Expected {codestyle.type_(exp_type)}, {node.id} is actually {codestyle.type_(param.type)}')
 
-                return VariableReference(act_type, node.id)
+                return VariableReference(param.type, param)
 
             if node.id in module.constant_defs:
                 cdef = module.constant_defs[node.id]
@@ -541,10 +539,10 @@ class OurVisitor:
             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 func.returns.__class__ != func.posonlyargs[0].type.__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].type)}')
 
-            if module.types['u8'].__class__ != func.posonlyargs[1][1].__class__:
+            if module.types['u8'].__class__ != func.posonlyargs[1].type.__class__:
                 _raise_static_error(node, 'Only folding over bytes (u8) is supported at this time')
 
             return Fold(
@@ -560,16 +558,16 @@ 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 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, param.type, arg_expr)
+            for arg_expr, param in zip(node.args, func.posonlyargs)
         )
         return result
 
@@ -586,7 +584,9 @@ class OurVisitor:
         if not node.value.id in our_locals:
             _raise_static_error(node, f'Undefined variable {node.value.id}')
 
-        node_typ = our_locals[node.value.id]
+        param = our_locals[node.value.id]
+
+        node_typ = param.type
         if not isinstance(node_typ, TypeStruct):
             _raise_static_error(node, f'Cannot take attribute of non-struct {node.value.id}')
 
@@ -598,7 +598,7 @@ class OurVisitor:
             _raise_static_error(node, f'Expected {codestyle.type_(exp_type)}, {node.value.id}.{member.name} is actually {codestyle.type_(member.type)}')
 
         return AccessStructMember(
-            VariableReference(node_typ, node.value.id),
+            VariableReference(node_typ, param),
             member,
         )
 
@@ -614,8 +614,9 @@ class OurVisitor:
 
         varref: Union[ModuleConstantReference, 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]
+            node_typ = param.type
+            varref = VariableReference(param.type, param)
         elif node.value.id in module.constant_defs:
             constant_def = module.constant_defs[node.value.id]
             node_typ = constant_def.type
@@ -642,12 +643,15 @@ class OurVisitor:
             )
 
         if isinstance(node_typ, TypeTuple):
-            if not isinstance(slice_expr, ConstantUInt32):
+            if not isinstance(slice_expr, ConstantPrimitive):
                 _raise_static_error(node, 'Must subscript using a constant index')
 
             idx = slice_expr.value
 
-            if len(node_typ.members) <= idx:
+            if not isinstance(idx, int):
+                _raise_static_error(node, 'Must subscript using a constant integer index')
+
+            if not (0 <= idx < len(node_typ.members)):
                 _raise_static_error(node, f'Index {idx} out of bounds for tuple {node.value.id}')
 
             tuple_member = node_typ.members[idx]
@@ -666,7 +670,7 @@ class OurVisitor:
             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):
+            if not isinstance(slice_expr, ConstantPrimitive):
                 return AccessStaticArrayMember(
                     varref,
                     node_typ,
@@ -675,7 +679,10 @@ class OurVisitor:
 
             idx = slice_expr.value
 
-            if len(node_typ.members) <= idx:
+            if not isinstance(idx, int):
+                _raise_static_error(node, 'Must subscript using an integer index')
+
+            if not (0 <= idx < len(node_typ.members)):
                 _raise_static_error(node, f'Index {idx} out of bounds for static array {node.value.id}')
 
             static_array_member = node_typ.members[idx]
@@ -688,73 +695,15 @@ class OurVisitor:
 
         _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}')
-
-            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}')
+        raise NotImplementedError(f'{node.value} as constant')
 
     def visit_type(self, module: Module, node: ast.expr) -> TypeBase:
         if isinstance(node, ast.Constant):

phasm/typer.py

@@ -0,0 +1,115 @@
+"""
+Type checks and enriches the given ast
+"""
+from . import ourlang
+
+from .typing import Context, TypeConstraintBitWidth, TypeConstraintPrimitive, TypeConstraintSigned, TypeVar
+
+def phasm_type(inp: ourlang.Module) -> None:
+    module(inp)
+
+def constant(ctx: 'Context', inp: ourlang.Constant) -> 'TypeVar':
+    if isinstance(inp, ourlang.ConstantPrimitive):
+        result = ctx.new_var()
+
+        if not isinstance(inp.value, int):
+            raise NotImplementedError('Float constants in new type system')
+
+        result.add_constraint(TypeConstraintPrimitive(TypeConstraintPrimitive.Primitive.INT))
+
+        # Need at least this many bits to store this constant value
+        result.add_constraint(TypeConstraintBitWidth(minb=len(bin(inp.value)) - 2))
+        # Don't dictate anything about signedness - you can use a signed
+        # constant in an unsigned variable if the bits fit
+        result.add_constraint(TypeConstraintSigned(None))
+
+        result.add_location(str(inp.value))
+
+        inp.type_var = result
+
+        return result
+
+    raise NotImplementedError(constant, inp)
+
+def expression(ctx: 'Context', inp: ourlang.Expression) -> 'TypeVar':
+    if isinstance(inp, ourlang.Constant):
+        return constant(ctx, inp)
+
+    if isinstance(inp, ourlang.VariableReference):
+        assert inp.variable.type_var is not None, inp
+        return inp.variable.type_var
+
+    if isinstance(inp, ourlang.BinaryOp):
+        if inp.operator not in ('+', '-', '|', '&', '^'):
+            raise NotImplementedError(expression, inp, inp.operator)
+
+        left = expression(ctx, inp.left)
+        right = expression(ctx, inp.right)
+        ctx.unify(left, right)
+        return left
+
+    if isinstance(inp, ourlang.FunctionCall):
+        assert inp.function.returns_type_var is not None
+        if inp.function.posonlyargs:
+            raise NotImplementedError
+
+        return inp.function.returns_type_var
+
+    raise NotImplementedError(expression, inp)
+
+def function(ctx: 'Context', inp: ourlang.Function) -> None:
+    if len(inp.statements) != 1 or not isinstance(inp.statements[0], ourlang.StatementReturn):
+        raise NotImplementedError('Functions with not just a return statement')
+    typ = expression(ctx, inp.statements[0].value)
+
+    assert inp.returns_type_var is not None
+    ctx.unify(inp.returns_type_var, typ)
+    return
+
+def module(inp: ourlang.Module) -> None:
+    ctx = Context()
+
+    for func in inp.functions.values():
+        func.returns_type_var = _convert_old_type(ctx, func.returns, f'{func.name}.(returns)')
+        for param in func.posonlyargs:
+            param.type_var = _convert_old_type(ctx, param.type, f'{func.name}.{param.name}')
+
+    for func in inp.functions.values():
+        function(ctx, func)
+
+from . import typing
+
+def _convert_old_type(ctx: Context, inp: typing.TypeBase, location: str) -> TypeVar:
+    result = ctx.new_var()
+
+    if isinstance(inp, typing.TypeUInt8):
+        result.add_constraint(TypeConstraintBitWidth(minb=8, maxb=8))
+        result.add_constraint(TypeConstraintSigned(False))
+        result.add_location(location)
+        return result
+
+    if isinstance(inp, typing.TypeUInt32):
+        result.add_constraint(TypeConstraintBitWidth(minb=32, maxb=32))
+        result.add_constraint(TypeConstraintSigned(False))
+        result.add_location(location)
+        return result
+
+    if isinstance(inp, typing.TypeUInt64):
+        result.add_constraint(TypeConstraintBitWidth(minb=64, maxb=64))
+        result.add_constraint(TypeConstraintSigned(False))
+        result.add_location(location)
+        return result
+
+    if isinstance(inp, typing.TypeInt32):
+        result.add_constraint(TypeConstraintBitWidth(minb=32, maxb=32))
+        result.add_constraint(TypeConstraintSigned(True))
+        result.add_location(location)
+        return result
+
+    if isinstance(inp, typing.TypeInt64):
+        result.add_constraint(TypeConstraintBitWidth(minb=64, maxb=64))
+        result.add_constraint(TypeConstraintSigned(True))
+        result.add_location(location)
+        return result
+
+    raise NotImplementedError(_convert_old_type, inp)

phasm/typing.py

@@ -1,7 +1,11 @@
 """
 The phasm type system
 """
-from typing import Optional, List
+from typing import Dict, Optional, List, Type
+
+import enum
+
+from .exceptions import TypingError
 
 class TypeBase:
     """
@@ -200,3 +204,176 @@ class TypeStruct(TypeBase):
             x.type.alloc_size()
             for x in self.members
         )
+
+## NEW STUFF BELOW
+
+class TypingNarrowProtoError(TypingError):
+    pass
+
+class TypingNarrowError(TypingError):
+    def __init__(self, l: 'TypeVar', r: 'TypeVar', msg: str) -> None:
+        super().__init__(
+            f'Cannot narrow types {l} and {r}: {msg}'
+        )
+
+class TypeConstraintBase:
+    def narrow(self, other: 'TypeConstraintBase') -> 'TypeConstraintBase':
+        raise NotImplementedError('narrow', self, other)
+
+class TypeConstraintPrimitive(TypeConstraintBase):
+    __slots__ = ('primitive', )
+
+    class Primitive(enum.Enum):
+        INT = 0
+        FLOAT = 1
+
+    primitive: Primitive
+
+    def __init__(self, primitive: Primitive) -> None:
+        self.primitive = primitive
+
+    def narrow(self, other: 'TypeConstraintBase') -> 'TypeConstraintPrimitive':
+        if not isinstance(other, TypeConstraintPrimitive):
+            raise Exception('Invalid comparison')
+
+        if self.primitive != other.primitive:
+            raise TypingNarrowProtoError('Primitive does not match')
+
+        return TypeConstraintPrimitive(self.primitive)
+
+    def __repr__(self) -> str:
+        return f'Primitive={self.primitive.name}'
+
+class TypeConstraintSigned(TypeConstraintBase):
+    __slots__ = ('signed', )
+
+    signed: Optional[bool]
+
+    def __init__(self, signed: Optional[bool]) -> None:
+        self.signed = signed
+
+    def narrow(self, other: 'TypeConstraintBase') -> 'TypeConstraintSigned':
+        if not isinstance(other, TypeConstraintSigned):
+            raise Exception('Invalid comparison')
+
+        if other.signed is None:
+            return TypeConstraintSigned(self.signed)
+        if self.signed is None:
+            return TypeConstraintSigned(other.signed)
+
+        if self.signed is not other.signed:
+            raise TypingNarrowProtoError('Signed does not match')
+
+        return TypeConstraintSigned(self.signed)
+
+    def __repr__(self) -> str:
+        return f'Signed={self.signed}'
+
+class TypeConstraintBitWidth(TypeConstraintBase):
+    __slots__ = ('minb', 'maxb', )
+
+    minb: int
+    maxb: int
+
+    def __init__(self, *, minb: int = 1, maxb: int = 64) -> None:
+        assert minb is not None or maxb is not None
+        assert maxb <= 64 # For now, support up to 64 bits values
+
+        self.minb = minb
+        self.maxb = maxb
+
+    def narrow(self, other: 'TypeConstraintBase') -> 'TypeConstraintBitWidth':
+        if not isinstance(other, TypeConstraintBitWidth):
+            raise Exception('Invalid comparison')
+
+        if self.minb > other.maxb:
+            raise TypingNarrowProtoError('Min bitwidth exceeds other max bitwidth')
+
+        if other.minb > self.maxb:
+            raise TypingNarrowProtoError('Other min bitwidth exceeds max bitwidth')
+
+        return TypeConstraintBitWidth(
+            minb=max(self.minb, other.minb),
+            maxb=min(self.maxb, other.maxb),
+        )
+
+    def __repr__(self) -> str:
+        return f'BitWidth={self.minb}..{self.maxb}'
+
+class TypeVar:
+    def __init__(self, ctx: 'Context') -> None:
+        self.context = ctx
+        self.constraints: Dict[Type[TypeConstraintBase], TypeConstraintBase] = {}
+        self.locations: List[str] = []
+
+    def add_constraint(self, newconst: TypeConstraintBase) -> None:
+        if newconst.__class__ in self.constraints:
+            self.constraints[newconst.__class__] = self.constraints[newconst.__class__].narrow(newconst)
+        else:
+            self.constraints[newconst.__class__] = newconst
+
+    def add_location(self, ref: str) -> None:
+        self.locations.append(ref)
+
+    def __repr__(self) -> str:
+        return (
+            'TypeVar<'
+            + '; '.join(map(repr, self.constraints.values()))
+            + '; locations: '
+            + ', '.join(self.locations)
+            + '>'
+        )
+
+class Context:
+    def new_var(self) -> TypeVar:
+        return TypeVar(self)
+
+    def unify(self, l: 'TypeVar', r: 'TypeVar') -> None:
+        newtypevar = self.new_var()
+
+        try:
+            for const in l.constraints.values():
+                newtypevar.add_constraint(const)
+            for const in r.constraints.values():
+                newtypevar.add_constraint(const)
+        except TypingNarrowProtoError as ex:
+            raise TypingNarrowError(l, r, str(ex)) from None
+
+        newtypevar.locations.extend(l.locations)
+        newtypevar.locations.extend(r.locations)
+
+        # Make pointer locations to the constraints and locations
+        # so they get linked together throughout the unification
+
+        l.constraints = newtypevar.constraints
+        l.locations = newtypevar.locations
+
+        r.constraints = newtypevar.constraints
+        r.locations = newtypevar.locations
+
+        return
+
+def simplify(inp: TypeVar) -> Optional[str]:
+    tc_prim = inp.constraints.get(TypeConstraintPrimitive)
+    tc_bits = inp.constraints.get(TypeConstraintBitWidth)
+    tc_sign = inp.constraints.get(TypeConstraintSigned)
+
+    if tc_prim is None:
+        return None
+
+    assert isinstance(tc_prim, TypeConstraintPrimitive) # type hint
+    primitive = tc_prim.primitive
+    if primitive is TypeConstraintPrimitive.Primitive.INT:
+        if tc_bits is None or tc_sign is None:
+            return None
+
+        assert isinstance(tc_bits, TypeConstraintBitWidth) # type hint
+        assert isinstance(tc_sign, TypeConstraintSigned) # type hint
+
+        if tc_sign.signed is None or tc_bits.minb != tc_bits.maxb or tc_bits.minb not in (8, 32, 64):
+            return None
+
+        base = 'i' if tc_sign.signed else 'u'
+        return f'{base}{tc_bits.minb}'
+
+    return None

tests/integration/runners.py

@@ -5,6 +5,7 @@ from typing import Any, Callable, Dict, Iterable, Optional, TextIO
 
 import ctypes
 import io
+import warnings
 
 import pywasm.binary
 import wasm3
@@ -13,6 +14,7 @@ import wasmtime
 
 from phasm.compiler import phasm_compile
 from phasm.parser import phasm_parse
+from phasm.typer import phasm_type
 from phasm import ourlang
 from phasm import wasm
 
@@ -40,6 +42,10 @@ class RunnerBase:
         Parses the Phasm code into an AST
         """
         self.phasm_ast = phasm_parse(self.phasm_code)
+        try:
+            phasm_type(self.phasm_ast)
+        except NotImplementedError as exc:
+            warnings.warn(f'phasm_type throws an NotImplementedError on this test: {exc}')
 
     def compile_ast(self) -> None:
         """

tests/integration/test_simple.py

@@ -304,6 +304,21 @@ def testEntry(a: i32, b: i32) -> i32:
     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_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 = """

tests/integration/test_type_checks.py

@@ -0,0 +1,31 @@
+import pytest
+
+from phasm.parser import phasm_parse
+from phasm.typer import phasm_type
+from phasm.exceptions import TypingError
+
+@pytest.mark.integration_test
+def test_constant_too_wide():
+    code_py = """
+def func_const() -> u8:
+    return 0xFFF
+"""
+
+    ast = phasm_parse(code_py)
+    with pytest.raises(TypingError, match='Other min bitwidth exceeds max bitwidth'):
+        phasm_type(ast)
+
+@pytest.mark.integration_test
+@pytest.mark.parametrize('type_', [32, 64])
+def test_signed_mismatch(type_):
+    code_py = f"""
+def func_const() -> u{type_}:
+    return 0
+
+def func_call() -> i{type_}:
+    return func_const()
+"""
+
+    ast = phasm_parse(code_py)
+    with pytest.raises(TypingError, match='Signed does not match'):
+        phasm_type(ast)