Type AST migration (#140): replace string-based types with structured Type enum#168
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Type AST migration (#140): replace string-based types with structured Type enum#168
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Introduce BuiltinType, GenericType, FunctionType, and Type enums/structs in compiler/common.casa. Add parse_type_str (str -> Type) and Type.format (Type -> str) with round-trip test coverage for builtins, generics, nested generics, function types, type vars, and named types.
str::starts_with, str::ends_with, str::contains, and str::find take needle/prefix/suffix as the first parameter. The original calls passed them as the second, so 'fn[T -> U]' parsed as a single-string Generic blob (base='fn[T -> U]', params=[]) instead of a real Type::Function. Type::format round-trips it correctly so the bug stayed undetected, but Type::substitute cannot decompose the blob, breaking trait default method synthesis (e.g. Iterable::map for non-generic receivers).
…signature Final piece of the Type AST migration (#167). make_named_param and make_signature now take Type / List[Type] directly, eliminating internal parse_type_str round-trips. apply_type_subs_to_sig and resolve_trait_sig operate on Type values via Type::substitute and TRAIT_SELF_TYPE checks. Adds direct test for Type::substitute on Type::Function nodes — the round-trip tests previously masked decomposition failures.
…_sig Inline the if/else branches by reassigning typ_str/ret_str when self matches, then parse once at the end. Same behavior, less repetition.
Eliminate format/parse round-trip on the non-self branch by passing param.typ and ret as Type values, parsing type_var once up front. Reduces work proportional to (params + returns) per trait method synthesis call.
Eliminates three parse_type_str call sites in syntax.casa by parsing the function-type string once at construction in build_hidden_trait_methods, then passing Type values through make_named_param and Variable directly.
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Summary
Implements PRD #140. Replaces stringly-typed compiler internals with a structured
Typeenum (Unknown,Builtin,Generic,Function,TypeVar).Closes issues #161-#167.
Per-commit breakdown
976a730Type AST foundation: enum,parse_type_str,Type.format, round-trip testse7ef718MigrateParameter.typ: str → Typea658ef5MigrateVariable.typandMember.typtoTypec64f7d1MigrateSignature.return_types: List[str] → List[Type]606f79eMigrateTypedStack.types: List[str] → List[Type]2f59857AddTypemethods:base,type_params,is_type_var,substitute45f1b12Fix RPN argument order inparse_type_str(str helpers; see below)83de95eRemove internal string boundaries atmake_named_param/make_signatureBug discovered and fixed
parse_type_strpassedstarts_with/ends_with/contains/findarguments in the wrong RPN order, soparse_type_str("fn[T -> U]")returned aGeneric{base="fn[T -> U]", params=[]}blob instead of a realType::Function.Type::formatround-tripped it correctly so the bug was masked, butType::substitutecouldn't decompose the blob — broke trait default method synthesis (e.g.Counter.mapfromIterable::map). Direct substitute test added intest_type_ast.casaas a regression guard.Notes on Casa enum move-semantics
Casa enum values (
Type,Option[T]) are move-semantic: a named variable is consumed on first method call.resolve_trait_sigtherefore uses a format → check → re-parse pattern when it needs to compare aTypeagainstTRAIT_SELF_TYPEand reuse it.signature_matchessimilarly stays str-based.Test plan
tests/test_compiler.sh < /dev/null— 28/28 passtests/test_examples.sh— 40/40 pass