ProXPL v1.5.0 Update: Traits Implementation (Phase 2)

This update represents the completion of Phase 2 of the ProXPL roadmap, successfully establishing the parsing and static analysis foundations for Traits and Generics within the language.

Summary of Changes

1. Abstract Syntax Tree (AST) Enhancements

We expanded the core representations for traits and classes:

• TypeInfo: Added a methods field (StmtList*). The Type Checker can now natively track methods associated with a class or trait type directly in the symbol table, rather than having to reconstruct or search the AST for method bodies on the fly.
• FuncDeclStmt and ClassDeclStmt: These AST nodes were enriched with genericParams and genericBounds (as StringList*), preparing the compiler for constraints like <T: Comparable>.
• ast.c: Factory functions createFuncDeclStmt and createClassDeclStmt were updated to initialize and store these generic arguments properly.

2. Parser Implementations

We implemented parser logic to parse generic arguments cleanly:

• Updated funcDecl and classDecl inside parser.c to look for generic tokens bounded by < and >.
• The parser can now pull out type variable names and map them against optional trait bounds following a colon (:).
• These parsed bounds are then passed to the enhanced AST factory functions mentioned above.

3. Type Checker Enforcement

The bulk of this update is centered on validating trait adherence during the compilation phase:

• Trait Adherence: In STMT_CLASS_DECL, if a class declares it implements a set of interfaces, the Type Checker now retrieves each trait's expected methods (using the updated TypeInfo symbols). It then iterates over those requirements, verifying that the class body contains a function definition matching the required method name. A type error is generated if the class fails to satisfy the contract.
• Bound Resolution: In both STMT_CLASS_DECL and STMT_FUNC_DECL, the generic bounds parsed out are checked against the symbol table. The Type Checker issues an error if a constraint references a trait that does not exist or if it points to a standard type rather than a trait/interface.
• Symbol Persistence: STMT_TRAIT_DECL and STMT_CLASS_DECL bodies have been modified so they register their methods onto their TypeInfo definitions immediately during the first pass.

Impact

This release fundamentally changes how polymorphism will be handled in ProXPL. By shifting to a robust constraint-checking architecture, the compiler can now guarantee structural and nominal type adherence prior to bytecode generation, pushing us significantly closer to our "Type Fortress" goals for v1.5.0.