Fix: You could assign structs to each other

As long as the arguments matched at least.

phasm/codestyle.py

@@ -63,7 +63,7 @@ def expression(inp: ourlang.Expression) -> str:
         ) + ', )'
 
     if isinstance(inp, ourlang.ConstantStruct):
-        return inp.struct_name + '(' + ', '.join(
+        return inp.struct_type3.name + '(' + ', '.join(
             expression(x)
             for x in inp.value
         ) + ')'

phasm/compiler.py

@@ -8,10 +8,18 @@ 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.functions import TypeVariable
-from .type3 import typeclasses as type3classes
-from .type3 import types as type3types
 from .type3.routers import NoRouteForTypeException, TypeApplicationRouter
+from .type3.typeclasses import Type3ClassMethod
+from .type3.types import (
+    IntType3,
+    Type3,
+    TypeApplication_Struct,
+    TypeApplication_TypeInt,
+    TypeApplication_TypeStar,
+    TypeConstructor_StaticArray,
+    TypeConstructor_Tuple,
+)
 from .wasmgenerator import Generator as WasmGenerator
 
 TYPE3_ASSERTION_ERROR = 'You must call phasm_type3 after calling phasm_parse before your program can be compiled'
@@ -37,7 +45,7 @@ def phasm_compile(inp: ourlang.Module) -> wasm.Module:
     """
     return module(inp)
 
-def type3(inp: type3types.Type3) -> wasm.WasmType:
+def type3(inp: Type3) -> wasm.WasmType:
     """
     Compile: type
 
@@ -98,18 +106,18 @@ def tuple_instantiation(wgn: WasmGenerator, inp: ourlang.TupleInstantiation) ->
     """
     assert inp.type3 is not None, TYPE3_ASSERTION_ERROR
 
-    args: tuple[type3types.Type3, ...]
+    args: tuple[Type3, ...]
 
-    if isinstance(inp.type3.application, type3types.TypeApplication_TypeStar):
+    if isinstance(inp.type3.application, TypeApplication_TypeStar):
         # Possibly paranoid assert. If we have a future variadic type,
         # does it also do this tuple instantation like this?
-        assert isinstance(inp.type3.application.constructor, type3types.TypeConstructor_Tuple)
+        assert isinstance(inp.type3.application.constructor, TypeConstructor_Tuple)
 
         args = inp.type3.application.arguments
-    elif isinstance(inp.type3.application, type3types.TypeApplication_TypeInt):
+    elif isinstance(inp.type3.application, TypeApplication_TypeInt):
         # Possibly paranoid assert. If we have a future type of kind * -> Int -> *,
         # does it also do this tuple instantation like this?
-        assert isinstance(inp.type3.application.constructor, type3types.TypeConstructor_StaticArray)
+        assert isinstance(inp.type3.application.constructor, TypeConstructor_StaticArray)
 
         sa_type, sa_len = inp.type3.application.arguments
 
@@ -162,7 +170,7 @@ def expression_subscript_bytes(
 
 def expression_subscript_static_array(
         attrs: tuple[WasmGenerator, ourlang.Subscript],
-        args: tuple[type3types.Type3, type3types.IntType3],
+        args: tuple[Type3, IntType3],
     ) -> None:
     wgn, inp = attrs
 
@@ -194,7 +202,7 @@ def expression_subscript_static_array(
 
 def expression_subscript_tuple(
         attrs: tuple[WasmGenerator, ourlang.Subscript],
-        args: tuple[type3types.Type3, ...],
+        args: tuple[Type3, ...],
     ) -> None:
     wgn, inp = attrs
 
@@ -292,16 +300,16 @@ def expression(wgn: WasmGenerator, inp: ourlang.Expression) -> None:
         expression(wgn, inp.left)
         expression(wgn, inp.right)
 
-        type_var_map: dict[type3functions.TypeVariable, type3types.Type3] = {}
+        type_var_map: dict[TypeVariable, Type3] = {}
 
         for type_var, arg_expr in zip(inp.operator.signature.args, [inp.left, inp.right, inp], strict=True):
             assert arg_expr.type3 is not None, TYPE3_ASSERTION_ERROR
 
-            if isinstance(type_var, type3types.Type3):
+            if isinstance(type_var, Type3):
                 # Fixed type, not part of the lookup requirements
                 continue
 
-            if isinstance(type_var, type3functions.TypeVariable):
+            if isinstance(type_var, TypeVariable):
                 type_var_map[type_var] = arg_expr.type3
                 continue
 
@@ -315,18 +323,18 @@ def expression(wgn: WasmGenerator, inp: ourlang.Expression) -> None:
         for arg in inp.arguments:
             expression(wgn, arg)
 
-        if isinstance(inp.function, type3classes.Type3ClassMethod):
+        if isinstance(inp.function, Type3ClassMethod):
             # FIXME: Duplicate code with BinaryOp
             type_var_map = {}
 
             for type_var, arg_expr in zip(inp.function.signature.args, inp.arguments + [inp], strict=True):
                 assert arg_expr.type3 is not None, TYPE3_ASSERTION_ERROR
 
-                if isinstance(type_var, type3types.Type3):
+                if isinstance(type_var, Type3):
                     # Fixed type, not part of the lookup requirements
                     continue
 
-                if isinstance(type_var, type3functions.TypeVariable):
+                if isinstance(type_var, TypeVariable):
                     type_var_map[type_var] = arg_expr.type3
                     continue
 
@@ -356,7 +364,7 @@ def expression(wgn: WasmGenerator, inp: ourlang.Expression) -> None:
     if isinstance(inp, ourlang.AccessStructMember):
         assert inp.struct_type3 is not None, TYPE3_ASSERTION_ERROR
 
-        assert isinstance(inp.struct_type3.application, type3types.TypeApplication_Struct)
+        assert isinstance(inp.struct_type3.application, TypeApplication_Struct)
 
         member_type = dict(inp.struct_type3.application.arguments)[inp.member]
 
@@ -739,7 +747,7 @@ def module(inp: ourlang.Module) -> wasm.Module:
     return result
 
 def _generate_struct_constructor(wgn: WasmGenerator, inp: ourlang.StructConstructor) -> None:
-    assert isinstance(inp.struct_type3.application, type3types.TypeApplication_Struct)
+    assert isinstance(inp.struct_type3.application, TypeApplication_Struct)
 
     st_args = inp.struct_type3.application.arguments
 

phasm/ourlang.py

@@ -98,21 +98,21 @@ class ConstantStruct(ConstantMemoryStored):
     """
     A Struct constant value expression within a statement
     """
-    __slots__ = ('struct_name', 'value', )
+    __slots__ = ('struct_type3', 'value', )
 
-    struct_name: str
+    struct_type3: Type3
     value: List[Union[ConstantPrimitive, ConstantBytes, ConstantTuple, 'ConstantStruct']]
 
-    def __init__(self, struct_name: str, value: List[Union[ConstantPrimitive, ConstantBytes, ConstantTuple, 'ConstantStruct']], data_block: 'ModuleDataBlock') -> None:
+    def __init__(self, struct_type3: Type3, value: List[Union[ConstantPrimitive, ConstantBytes, ConstantTuple, 'ConstantStruct']], data_block: 'ModuleDataBlock') -> None:
         super().__init__(data_block)
-        self.struct_name = struct_name
+        self.struct_type3 = struct_type3
         self.value = value
 
     def __repr__(self) -> str:
         # Do not repr the whole ModuleDataBlock
         # As this has a reference back to this constant for its data
         # which it needs to compile the data into the program
-        return f'ConstantStruct({repr(self.struct_name)}, {repr(self.value)}, @{repr(self.data_block.address)})'
+        return f'ConstantStruct({self.struct_type3!r}, {self.value!r}, @{self.data_block.address!r})'
 
 class VariableReference(Expression):
     """

phasm/parser.py

@@ -32,8 +32,8 @@ from .ourlang import (
     VariableReference,
 )
 from .prelude import PRELUDE_METHODS, PRELUDE_OPERATORS, PRELUDE_TYPES
-from .type3 import typeclasses as type3typeclasses
+from .type3.typeclasses import Type3ClassMethod
-from .type3 import types as type3types
+from .type3.types import IntType3, Type3
 
 
 def phasm_parse(source: str) -> Module:
@@ -226,7 +226,7 @@ class OurVisitor:
         _not_implemented(not node.keywords, 'ClassDef.keywords')
         _not_implemented(not node.decorator_list, 'ClassDef.decorator_list')
 
-        members: Dict[str, type3types.Type3] = {}
+        members: Dict[str, Type3] = {}
 
         for stmt in node.body:
             if not isinstance(stmt, ast.AnnAssign):
@@ -352,7 +352,7 @@ class OurVisitor:
 
     def visit_Module_FunctionDef_expr(self, module: Module, function: Function, our_locals: OurLocals, node: ast.expr) -> Expression:
         if isinstance(node, ast.BinOp):
-            operator: Union[str, type3typeclasses.Type3ClassMethod]
+            operator: Union[str, Type3ClassMethod]
 
             if isinstance(node.op, ast.Add):
                 operator = '+'
@@ -471,7 +471,7 @@ class OurVisitor:
         if not isinstance(node.func.ctx, ast.Load):
             _raise_static_error(node, 'Must be load context')
 
-        func: Union[Function, type3typeclasses.Type3ClassMethod]
+        func: Union[Function, Type3ClassMethod]
 
         if node.func.id in PRELUDE_METHODS:
             func = PRELUDE_METHODS[node.func.id]
@@ -584,7 +584,8 @@ class OurVisitor:
             if not isinstance(node.func.ctx, ast.Load):
                 _raise_static_error(node.func, 'Must be load context')
 
-            if node.func.id not in module.struct_definitions:
+            struct_def = module.struct_definitions.get(node.func.id)
+            if struct_def is None:
                 _raise_static_error(node.func, 'Undefined struct')
 
             if node.keywords:
@@ -600,7 +601,7 @@ class OurVisitor:
 
             data_block = ModuleDataBlock(struct_data)
             module.data.blocks.append(data_block)
-            return ConstantStruct(node.func.id, struct_data, data_block)
+            return ConstantStruct(struct_def.struct_type3, struct_data, data_block)
 
         _not_implemented(node.kind is None, 'Constant.kind')
 
@@ -617,7 +618,7 @@ class OurVisitor:
 
         raise NotImplementedError(f'{node.value} as constant')
 
-    def visit_type(self, module: Module, node: ast.expr) -> type3types.Type3:
+    def visit_type(self, module: Module, node: ast.expr) -> Type3:
         if isinstance(node, ast.Constant):
             if node.value is None:
                 return prelude.none
@@ -645,7 +646,7 @@ class OurVisitor:
 
             return prelude.static_array(
                 self.visit_type(module, node.value),
-                type3types.IntType3(node.slice.value),
+                IntType3(node.slice.value),
             )
 
         if isinstance(node, ast.Tuple):

phasm/type3/constraints.py

@@ -6,9 +6,19 @@ These need to be resolved before the program can be compiled.
 from typing import Any, Dict, Iterable, List, Optional, Tuple, Union
 
 from .. import ourlang, prelude
-from . import placeholders, typeclasses, types
+from .placeholders import PlaceholderForType, Type3OrPlaceholder
-from .placeholders import PlaceholderForType
 from .routers import NoRouteForTypeException, TypeApplicationRouter
+from .typeclasses import Type3Class
+from .types import (
+    IntType3,
+    Type3,
+    TypeApplication_Nullary,
+    TypeApplication_Struct,
+    TypeApplication_TypeInt,
+    TypeApplication_TypeStar,
+    TypeConstructor_Base,
+    TypeConstructor_Struct,
+)
 
 
 class Error:
@@ -34,13 +44,13 @@ class RequireTypeSubstitutes:
     typing of the program, so this constraint can be updated.
     """
 
-SubstitutionMap = Dict[placeholders.PlaceholderForType, types.Type3]
+SubstitutionMap = Dict[PlaceholderForType, Type3]
 
 NewConstraintList = List['ConstraintBase']
 
 CheckResult = Union[None, SubstitutionMap, Error, NewConstraintList, RequireTypeSubstitutes]
 
-HumanReadableRet = Tuple[str, Dict[str, Union[str, ourlang.Expression, types.Type3, placeholders.PlaceholderForType]]]
+HumanReadableRet = Tuple[str, Dict[str, Union[None, int, str, ourlang.Expression, Type3, PlaceholderForType]]]
 
 class Context:
     """
@@ -50,7 +60,7 @@ class Context:
     __slots__ = ('type_class_instances_existing', )
 
     # Constraint_TypeClassInstanceExists
-    type_class_instances_existing: set[tuple[typeclasses.Type3Class, tuple[Union[types.Type3, types.TypeConstructor_Base[Any], types.TypeConstructor_Struct], ...]]]
+    type_class_instances_existing: set[tuple[Type3Class, tuple[Union[Type3, TypeConstructor_Base[Any], TypeConstructor_Struct], ...]]]
 
     def __init__(self) -> None:
         self.type_class_instances_existing = set()
@@ -100,23 +110,23 @@ class SameTypeConstraint(ConstraintBase):
     """
     __slots__ = ('type_list', )
 
-    type_list: List[placeholders.Type3OrPlaceholder]
+    type_list: List[Type3OrPlaceholder]
 
-    def __init__(self, *type_list: placeholders.Type3OrPlaceholder, comment: Optional[str] = None) -> None:
+    def __init__(self, *type_list: Type3OrPlaceholder, comment: Optional[str] = None) -> None:
         super().__init__(comment=comment)
 
         assert len(type_list) > 1
         self.type_list = [*type_list]
 
     def check(self) -> CheckResult:
-        known_types: List[types.Type3] = []
+        known_types: List[Type3] = []
         phft_list = []
         for typ in self.type_list:
-            if isinstance(typ, types.Type3):
+            if isinstance(typ, Type3):
                 known_types.append(typ)
                 continue
 
-            if isinstance(typ, placeholders.PlaceholderForType):
+            if isinstance(typ, PlaceholderForType):
                 if typ.resolve_as is not None:
                     known_types.append(typ.resolve_as)
                 else:
@@ -133,7 +143,7 @@ class SameTypeConstraint(ConstraintBase):
             if ktyp != first_type:
                 return Error(f'{ktyp:s} must be {first_type:s} instead', comment=self.comment)
 
-        if not placeholders:
+        if not phft_list:
             return None
 
         for phft in phft_list:
@@ -177,10 +187,10 @@ class SameTypeArgumentConstraint(ConstraintBase):
         tc_typ = self.tc_var.resolve_as
         arg_typ = self.arg_var.resolve_as
 
-        if isinstance(tc_typ.application, types.TypeApplication_Nullary):
+        if isinstance(tc_typ.application, TypeApplication_Nullary):
             return Error(f'{tc_typ:s} must be a constructed type instead')
 
-        if isinstance(tc_typ.application, types.TypeApplication_TypeStar):
+        if isinstance(tc_typ.application, TypeApplication_TypeStar):
             # Sure, it's a constructed type. But it's like a struct,
             # though without the way to implement type classes
             # Presumably, doing a naked `foo :: t a -> a`
@@ -190,7 +200,7 @@ class SameTypeArgumentConstraint(ConstraintBase):
 
         # FIXME: This feels sketchy. Shouldn't the type variable
         # have the exact same number as arguments?
-        if isinstance(tc_typ.application, types.TypeApplication_TypeInt):
+        if isinstance(tc_typ.application, TypeApplication_TypeInt):
             if tc_typ.application.arguments[0] == arg_typ:
                 return None
 
@@ -201,16 +211,16 @@ class SameTypeArgumentConstraint(ConstraintBase):
 class TupleMatchConstraint(ConstraintBase):
     __slots__ = ('exp_type', 'args', )
 
-    exp_type: placeholders.Type3OrPlaceholder
+    exp_type: Type3OrPlaceholder
-    args: list[placeholders.Type3OrPlaceholder]
+    args: list[Type3OrPlaceholder]
 
-    def __init__(self, exp_type: placeholders.Type3OrPlaceholder, args: Iterable[placeholders.Type3OrPlaceholder], comment: str):
+    def __init__(self, exp_type: Type3OrPlaceholder, args: Iterable[Type3OrPlaceholder], comment: str):
         super().__init__(comment=comment)
 
         self.exp_type = exp_type
         self.args = list(args)
 
-    def _generate_static_array(self, sa_args: tuple[types.Type3, types.IntType3]) -> CheckResult:
+    def _generate_static_array(self, sa_args: tuple[Type3, IntType3]) -> CheckResult:
         sa_type, sa_len = sa_args
 
         if sa_len.value != len(self.args):
@@ -221,7 +231,7 @@ class TupleMatchConstraint(ConstraintBase):
             for arg in self.args
         ]
 
-    def _generate_tuple(self, tp_args: tuple[types.Type3, ...]) -> CheckResult:
+    def _generate_tuple(self, tp_args: tuple[Type3, ...]) -> CheckResult:
         if len(tp_args) != len(self.args):
             return Error('Mismatch between applied types argument count', comment=self.comment)
 
@@ -236,7 +246,7 @@ class TupleMatchConstraint(ConstraintBase):
 
     def check(self) -> CheckResult:
         exp_type = self.exp_type
-        if isinstance(exp_type, placeholders.PlaceholderForType):
+        if isinstance(exp_type, PlaceholderForType):
             if exp_type.resolve_as is None:
                 return RequireTypeSubstitutes()
 
@@ -254,34 +264,34 @@ class MustImplementTypeClassConstraint(ConstraintBase):
     __slots__ = ('context', 'type_class3', 'types', )
 
     context: Context
-    type_class3: Union[str, typeclasses.Type3Class]
+    type_class3: Union[str, Type3Class]
-    types: list[placeholders.Type3OrPlaceholder]
+    types: list[Type3OrPlaceholder]
 
     DATA = {
         'bytes': {'Foldable'},
     }
 
-    def __init__(self, context: Context, type_class3: Union[str, typeclasses.Type3Class], types: list[placeholders.Type3OrPlaceholder], comment: Optional[str] = None) -> None:
+    def __init__(self, context: Context, type_class3: Union[str, Type3Class], typ_list: list[Type3OrPlaceholder], comment: Optional[str] = None) -> None:
         super().__init__(comment=comment)
 
         self.context = context
         self.type_class3 = type_class3
-        self.types = types
+        self.types = typ_list
 
     def check(self) -> CheckResult:
-        typ_list: list[types.Type3 | types.TypeConstructor_Base[Any] | types.TypeConstructor_Struct] = []
+        typ_list: list[Type3 | TypeConstructor_Base[Any] | TypeConstructor_Struct] = []
         for typ in self.types:
-            if isinstance(typ, placeholders.PlaceholderForType) and typ.resolve_as is not None:
+            if isinstance(typ, PlaceholderForType) and typ.resolve_as is not None:
                 typ = typ.resolve_as
 
-            if isinstance(typ, placeholders.PlaceholderForType):
+            if isinstance(typ, PlaceholderForType):
                 return RequireTypeSubstitutes()
 
-            if isinstance(typ.application, (types.TypeApplication_Nullary, types.TypeApplication_Struct, )):
+            if isinstance(typ.application, (TypeApplication_Nullary, TypeApplication_Struct, )):
                 typ_list.append(typ)
                 continue
 
-            if isinstance(typ.application, (types.TypeApplication_TypeInt, types.TypeApplication_TypeStar)):
+            if isinstance(typ.application, (TypeApplication_TypeInt, TypeApplication_TypeStar)):
                 typ_list.append(typ.application.constructor)
                 continue
 
@@ -289,7 +299,7 @@ class MustImplementTypeClassConstraint(ConstraintBase):
 
         assert len(typ_list) == len(self.types)
 
-        if isinstance(self.type_class3, typeclasses.Type3Class):
+        if isinstance(self.type_class3, Type3Class):
             key = (self.type_class3, tuple(typ_list), )
             if key in self.context.type_class_instances_existing:
                 return None
@@ -324,12 +334,12 @@ class LiteralFitsConstraint(ConstraintBase):
     """
     __slots__ = ('type3', 'literal', )
 
-    type3: placeholders.Type3OrPlaceholder
+    type3: Type3OrPlaceholder
     literal: Union[ourlang.ConstantPrimitive, ourlang.ConstantBytes, ourlang.ConstantTuple, ourlang.ConstantStruct]
 
     def __init__(
             self,
-            type3: placeholders.Type3OrPlaceholder,
+            type3: Type3OrPlaceholder,
             literal: Union[ourlang.ConstantPrimitive, ourlang.ConstantBytes, ourlang.ConstantTuple, ourlang.ConstantStruct],
             comment: Optional[str] = None,
         ) -> None:
@@ -338,7 +348,7 @@ class LiteralFitsConstraint(ConstraintBase):
         self.type3 = type3
         self.literal = literal
 
-    def _generate_static_array(self, sa_args: tuple[types.Type3, types.IntType3]) -> CheckResult:
+    def _generate_static_array(self, sa_args: tuple[Type3, IntType3]) -> CheckResult:
         if not isinstance(self.literal, ourlang.ConstantTuple):
             return Error('Must be tuple', comment=self.comment)
 
@@ -364,7 +374,7 @@ class LiteralFitsConstraint(ConstraintBase):
 
         return res
 
-    def _generate_struct(self, st_args: tuple[tuple[str, types.Type3], ...]) -> CheckResult:
+    def _generate_struct(self, st_args: tuple[tuple[str, Type3], ...]) -> CheckResult:
         if not isinstance(self.literal, ourlang.ConstantStruct):
             return Error('Must be struct')
 
@@ -382,13 +392,19 @@ class LiteralFitsConstraint(ConstraintBase):
         # gets updated when we figure out the type of the
         # expression the literal is used in
         res.extend(
-            SameTypeConstraint(x_t, PlaceholderForType([y]), comment=f'{self.literal.struct_name}.{x_n}')
+            SameTypeConstraint(x_t, PlaceholderForType([y]), comment=f'{self.literal.struct_type3.name}.{x_n}')
             for (x_n, x_t, ), y in zip(st_args, self.literal.value, strict=True)
         )
 
+        res.append(SameTypeConstraint(
+            self.literal.struct_type3,
+            self.type3,
+            comment='Struct types must match',
+        ))
+
         return res
 
-    def _generate_tuple(self, tp_args: tuple[types.Type3, ...]) -> CheckResult:
+    def _generate_tuple(self, tp_args: tuple[Type3, ...]) -> CheckResult:
         if not isinstance(self.literal, ourlang.ConstantTuple):
             return Error('Must be tuple', comment=self.comment)
 
@@ -432,7 +448,7 @@ class LiteralFitsConstraint(ConstraintBase):
             'f64': None,
         }
 
-        if isinstance(self.type3, placeholders.PlaceholderForType):
+        if isinstance(self.type3, PlaceholderForType):
             if self.type3.resolve_as is None:
                 return RequireTypeSubstitutes()
 
@@ -490,65 +506,59 @@ class CanBeSubscriptedConstraint(ConstraintBase):
     """
     A value that is subscipted, i.e. a[0] (tuple) or a[b] (static array)
     """
-    __slots__ = ('ret_type3', 'type3', 'index', 'index_phft', )
+    __slots__ = ('ret_type3', 'type3', 'index_type3', 'index_const', )
 
-    ret_type3: placeholders.Type3OrPlaceholder
+    ret_type3: PlaceholderForType
-    type3: placeholders.Type3OrPlaceholder
+    type3: PlaceholderForType
-    index: ourlang.Expression
+    index_type3: PlaceholderForType
-    index_phft: placeholders.Type3OrPlaceholder
+    index_const: int | None
 
     def __init__(
             self,
-            ret_type3: placeholders.PlaceholderForType,
+            ret_type3: PlaceholderForType,
-            type3: placeholders.PlaceholderForType,
+            type3: PlaceholderForType,
-            index: ourlang.Expression,
+            index_type3: PlaceholderForType,
-            index_phft: placeholders.PlaceholderForType,
+            index_const: int | None,
             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
+        self.index_const = index_const
 
     def _generate_bytes(self) -> CheckResult:
         return [
-            SameTypeConstraint(prelude.u32, self.index_phft, comment='([]) :: bytes -> u32 -> u8'),
+            SameTypeConstraint(prelude.u32, self.index_type3, comment='([]) :: bytes -> u32 -> u8'),
             SameTypeConstraint(prelude.u8, self.ret_type3, comment='([]) :: bytes -> u32 -> u8'),
         ]
 
-    def _generate_static_array(self, sa_args: tuple[types.Type3, types.IntType3]) -> CheckResult:
+    def _generate_static_array(self, sa_args: tuple[Type3, IntType3]) -> CheckResult:
         sa_type, sa_len = sa_args
 
-        if isinstance(self.index, ourlang.ConstantPrimitive):
+        if self.index_const is not None and (self.index_const < 0 or sa_len.value <= self.index_const):
-            assert isinstance(self.index.value, int)
-
-            if self.index.value < 0 or sa_len.value <= self.index.value:
             return Error('Tuple index out of range')
 
         return [
-            SameTypeConstraint(prelude.u32, self.index_phft, comment='([]) :: Subscriptable a => a b -> u32 -> b'),
+            SameTypeConstraint(prelude.u32, self.index_type3, comment='([]) :: Subscriptable a => a b -> u32 -> b'),
             SameTypeConstraint(sa_type, self.ret_type3, comment='([]) :: Subscriptable a => a b -> u32 -> b'),
         ]
 
-    def _generate_tuple(self, tp_args: tuple[types.Type3, ...]) -> CheckResult:
+    def _generate_tuple(self, tp_args: tuple[Type3, ...]) -> CheckResult:
         # We special case tuples to allow for ease of use to the programmer
         # e.g. rather than having to do `fst a` and `snd a` and only have to-sized tuples
         # we use a[0] and a[1] and allow for a[2] and on.
 
-        if not isinstance(self.index, ourlang.ConstantPrimitive):
+        if self.index_const is None:
-            return Error('Must index with literal')
-
-        if not isinstance(self.index.value, int):
             return Error('Must index with integer literal')
 
-        if self.index.value < 0 or len(tp_args) <= self.index.value:
+        if self.index_const < 0 or len(tp_args) <= self.index_const:
             return Error('Tuple index out of range')
 
         return [
-            SameTypeConstraint(prelude.u32, self.index_phft, comment=f'Tuple subscript index {self.index.value}'),
+            SameTypeConstraint(prelude.u32, self.index_type3, comment='([]) :: Subscriptable a => a b -> u32 -> b'),
-            SameTypeConstraint(tp_args[self.index.value], self.ret_type3, comment=f'Tuple subscript index {self.index.value}'),
+            SameTypeConstraint(tp_args[self.index_const], self.ret_type3, comment=f'Tuple subscript index {self.index_const}'),
         ]
 
     GENERATE_ROUTER = TypeApplicationRouter['CanBeSubscriptedConstraint', CheckResult]()
@@ -557,12 +567,10 @@ class CanBeSubscriptedConstraint(ConstraintBase):
     GENERATE_ROUTER.add(prelude.tuple_, _generate_tuple)
 
     def check(self) -> CheckResult:
-        exp_type = self.type3
+        if self.type3.resolve_as is None:
-        if isinstance(exp_type, placeholders.PlaceholderForType):
-            if exp_type.resolve_as is None:
             return RequireTypeSubstitutes()
 
-            exp_type = exp_type.resolve_as
+        exp_type = self.type3.resolve_as
 
         try:
             return self.__class__.GENERATE_ROUTER(self, exp_type)
@@ -574,9 +582,9 @@ class CanBeSubscriptedConstraint(ConstraintBase):
             '{type3}[{index}]',
             {
                 'type3': self.type3,
-                'index': self.index,
+                'index': self.index_type3 if self.index_const is None else self.index_const,
             },
         )
 
     def __repr__(self) -> str:
-        return f'CanBeSubscriptedConstraint({repr(self.type3)}, {repr(self.index)}, comment={repr(self.comment)})'
+        return f'CanBeSubscriptedConstraint({self.ret_type3!r}, {self.type3!r}, {self.index_type3!r}, {self.index_const!r}, comment={repr(self.comment)})'

phasm/type3/constraintsgenerator.py

@@ -6,10 +6,6 @@ The constraints solver can then try to resolve all constraints.
 from typing import Generator, List
 
 from .. import ourlang, prelude
-from . import functions as functions
-from . import placeholders as placeholders
-from . import typeclasses as typeclasses
-from . import types as type3types
 from .constraints import (
     CanBeSubscriptedConstraint,
     ConstraintBase,
@@ -20,7 +16,14 @@ from .constraints import (
     SameTypeConstraint,
     TupleMatchConstraint,
 )
+from .functions import (
+    Constraint_TypeClassInstanceExists,
+    FunctionSignature,
+    TypeVariable,
+    TypeVariableApplication_Unary,
+)
 from .placeholders import PlaceholderForType
+from .types import Type3, TypeApplication_Struct
 
 ConstraintGenerator = Generator[ConstraintBase, None, None]
 
@@ -30,7 +33,7 @@ def phasm_type3_generate_constraints(inp: ourlang.Module) -> List[ConstraintBase
 
     return [*module(ctx, inp)]
 
-def constant(ctx: Context, inp: ourlang.Constant, phft: placeholders.PlaceholderForType) -> ConstraintGenerator:
+def constant(ctx: Context, inp: ourlang.Constant, phft: PlaceholderForType) -> ConstraintGenerator:
     if isinstance(inp, (ourlang.ConstantPrimitive, ourlang.ConstantBytes, ourlang.ConstantTuple, ourlang.ConstantStruct)):
         yield LiteralFitsConstraint(
             phft, inp,
@@ -63,7 +66,7 @@ def expression_function_call(ctx: Context, inp: ourlang.FunctionCall, phft: Plac
 def _expression_function_call(
         ctx: Context,
         func_name: str,
-        signature: functions.FunctionSignature,
+        signature: FunctionSignature,
         arguments: list[ourlang.Expression],
         return_expr: ourlang.Expression,
         return_phft: PlaceholderForType,
@@ -92,13 +95,13 @@ def _expression_function_call(
     # placeholder here. These don't need to update anything once
     # subsituted - that's done by arg_placeholders.
     type_var_map = {
-        x: placeholders.PlaceholderForType([])
+        x: PlaceholderForType([])
         for x in signature.args
-        if isinstance(x, functions.TypeVariable)
+        if isinstance(x, TypeVariable)
     }
 
     for constraint in signature.context.constraints:
-        if isinstance(constraint, functions.Constraint_TypeClassInstanceExists):
+        if isinstance(constraint, Constraint_TypeClassInstanceExists):
             yield MustImplementTypeClassConstraint(
                 ctx,
                 constraint.type_class3,
@@ -113,7 +116,7 @@ def _expression_function_call(
     # That is, given `foo :: t a -> a` we need to ensure
     # that both a's are the same.
     for sig_arg in signature.args:
-        if isinstance(sig_arg, type3types.Type3):
+        if isinstance(sig_arg, Type3):
             # Not a type variable at all
             continue
 
@@ -121,7 +124,7 @@ def _expression_function_call(
             # Not a type variable for a type constructor
             continue
 
-        if not isinstance(sig_arg.application, functions.TypeVariableApplication_Unary):
+        if not isinstance(sig_arg.application, TypeVariableApplication_Unary):
             raise NotImplementedError(sig_arg.application)
 
         assert sig_arg.application.arguments in type_var_map  # When does this happen?
@@ -139,18 +142,18 @@ def _expression_function_call(
         else:
             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):
+        if isinstance(sig_part, TypeVariable):
             yield SameTypeConstraint(type_var_map[sig_part], arg_placeholders[arg_expr], comment=comment)
             continue
 
-        if isinstance(sig_part, type3types.Type3):
+        if isinstance(sig_part, Type3):
             yield SameTypeConstraint(sig_part, arg_placeholders[arg_expr], comment=comment)
             continue
 
         raise NotImplementedError(sig_part)
     return
 
-def expression(ctx: Context, inp: ourlang.Expression, phft: placeholders.PlaceholderForType) -> ConstraintGenerator:
+def expression(ctx: Context, inp: ourlang.Expression, phft: PlaceholderForType) -> ConstraintGenerator:
     if isinstance(inp, ourlang.Constant):
         yield from constant(ctx, inp, phft)
         return
@@ -190,11 +193,14 @@ def expression(ctx: Context, inp: ourlang.Expression, phft: placeholders.Placeho
         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)
+        if isinstance(inp.index, ourlang.ConstantPrimitive) and isinstance(inp.index.value, int):
+            yield CanBeSubscriptedConstraint(phft, varref_phft, index_phft, inp.index.value)
+        else:
+            yield CanBeSubscriptedConstraint(phft, varref_phft, index_phft, None)
         return
 
     if isinstance(inp, ourlang.AccessStructMember):
-        assert isinstance(inp.struct_type3.application, type3types.TypeApplication_Struct)  # FIXME: See test_struct.py::test_struct_not_accessible
+        assert isinstance(inp.struct_type3.application, TypeApplication_Struct)  # FIXME: See test_struct.py::test_struct_not_accessible
 
         mem_typ = dict(inp.struct_type3.application.arguments)[inp.member]
 

tests/integration/test_lang/test_struct.py

@@ -64,6 +64,36 @@ def helper(shape1: Rectangle, shape2: Rectangle) -> i32:
 
     assert 545 == result.returned_value
 
+@pytest.mark.integration_test
+def test_type_mismatch_struct_call_root():
+    code_py = """
+class CheckedValueBlue:
+    value: i32
+
+class CheckedValueRed:
+    value: i32
+
+CONST: CheckedValueBlue = CheckedValueRed(1)
+"""
+
+    with pytest.raises(Type3Exception, match='CheckedValueBlue must be CheckedValueRed instead'):
+        Suite(code_py).run_code()
+
+@pytest.mark.integration_test
+def test_type_mismatch_struct_call_nested():
+    code_py = """
+class CheckedValueBlue:
+    value: i32
+
+class CheckedValueRed:
+    value: i32
+
+CONST: (CheckedValueBlue, u32, ) = (CheckedValueRed(1), 16, )
+"""
+
+    with pytest.raises(Type3Exception, match='CheckedValueBlue must be CheckedValueRed instead'):
+        Suite(code_py).run_code()
+
 @pytest.mark.integration_test
 @pytest.mark.parametrize('type_', ['i32', 'i64', 'f32', 'f64'])
 def test_type_mismatch_struct_member(type_):

tests/integration/test_lang/test_subscriptable.py

@@ -64,7 +64,7 @@ def testEntry(x: (u8, u32, u64), y: u8) -> u64:
     return x[y]
 """
 
-    with pytest.raises(Type3Exception, match='Must index with literal'):
+    with pytest.raises(Type3Exception, match='Must index with integer literal'):
         Suite(code_py).run_code()
 
 @pytest.mark.integration_test