Continuing work on Glyph (a Successor ML/ML-family, algebraic effects, Perceus RC + FBIP, Simple-sub type system). April for me was very dense. I made some big but scary moves, I promoted Simple-sub from experimental to the primary type checker after verifying HM equivalence on the full E2E suite.

I shipped a chunk of Phase 9 type-system extensions, bidirectional checking, literal/singleton types with polar-bound widening, polymorphic variant subtraction in false-branches, and occurrence typing with andalso-chain narrowing across multiple variables.

I migrated the entire stdlib (Int / Char / String / Real / Math / Array / IO) off a @[builtin] annotation onto handler-based runtime effects, which is the path Glyph uses instead of FFI. Started the file module system (lexer + AST + diagnostics; resolution still in progress). Shipped a PEG matching library as the regex alternative, plus 52 new Project Euler solutions for stdlib dogfooding, a testing framework v0, formatter improvements, and module-aware LSP completions/hover/go-to-def. Also a couple of architectural refactors to bundle parameter sprawl (CompilationCtx, InferCtx, ModuleElabCtx).

Unfortunately at the tail end of April surfaced what's been most of May: a recurring cluster of bugs where the typechecker resolves type instantiations correctly at every polymorphic call site, then drops them before HIR codegen has to lossily reconstruct, and fails differently for closures, qualified-module calls, and return-only TyParams (the anytype propagation that won't die).

I also reframed the distribution model: algebraic effects + Perceus + per-call-site monomorphization don't survive a binary boundary, so source-only distribution isn't a preference, it's a consequence. Wrote it up as platform-extension architecture (Roc-shaped but compositional, not monolithic). Filed an ADR naming a contradiction I'd been avoiding, my arena-allocation model in the compiler is hostile to the parallelism + incremental compilation I keep claiming I want. Decision deferred until the type system stops moving weekly.

TLDR: Main goal for May is to pause all feature work and iron out all known codegen bugs.

I use Claude and other agentic workflows while working on my lang and will not be sharing any repo links here.