writeonce/docs/stories/language-runtime-database/05-language-surface.md

Iteration 5 — language surface (Haxe-parity adoptions)

Format: product/story-iteration-template. Part of Story — one language, one runtime, one database, one binary.

Goals

• The language grows from milestone grammar to a daily-driver surface: the systems-track verdict table's every adopt row — switch expressions, typedef records with ?fields, ?T optionals with null-narrowing, enum payload variants, try/catch/throw over traps, static members, abstract newtypes, using extensions, use modules, is, pub / pub(read), #if build flags, string interpolation, loop control.
• Every reject row (inheritance, Dynamic, cast, macros, FFI…) refuses with a diagnostic citing doctrine — the language's boundaries are as deliberate as its features.

Acceptance Criteria

• What to achieve?
  • Given the verdict table in the systems-track spec,
  • when the corpus runs,
  • then every adopt row has at least one golden fixture and one must-fail fixture passing, and every reject row that would parse produces its doctrine-citing diagnostic.
• What to achieve?
  • Given a switch over a union missing one variant and lacking default,
  • when it compiles,
  • then the diagnostic names exactly the missing variants.
• What to achieve?
  • Given the three fenced VM changes (catch frames, variant objects, boxed scalar optionals),
  • when they land,
  • then the format doc is updated in the same change and all prior trap fixtures still pass byte-for-byte.

Out Of Scope

• Stdlib modules and program mode (iteration 6).
• Any new VM capability beyond the three fenced changes.

Info

• Normative table: docs/superpowers/specs/2026-08-01-systems-track-design.md Part 1.
• Order inside the plan matters: modules first (everything imports through them), data shapes before optionals, rejects last.

Proposed Solution

• Execute the existing plan: compiler/plan/2026-08-01-haxe-parity-language.md (nine tasks, each shipping its fixtures and error-catalog entries in the same task).