giles d75c61d408 GUEST: step 7 — lib/guest/layout.sx off-side / layout-sensitive lexer ...

Configurable layout pass that inserts virtual open / close / separator
tokens based on indentation. Supports both styles the brief calls out:

  • Haskell-flavour: layout opens AFTER a reserved keyword
    (let/where/do/of) and resolves to the next token's column. Module
    prelude wraps the whole input in an implicit block. Explicit `{`
    after the keyword suppresses virtual layout.

  • Python-flavour: layout opens via an :open-trailing-fn predicate
    fired AFTER the trigger token (e.g. trailing `:`) — and resolves
    to the column of the next token, which in real source is on a
    fresh line. No module prelude.

Public entry: (layout-pass cfg tokens). Token shape: dict with at
least :type :value :line :col; everything else passes through. Newline
filler tokens are NOT used — line-break detection is via :line.

lib/guest/tests/layout.sx — 6 tests covering both flavours:
  haskell-do-block / haskell-explicit-brace / haskell-do-inline /
  haskell-module-prelude / python-if-block / python-nested.

Per the brief's gotcha note ("Don't ship lib/guest/layout.sx unless
the haskell scoreboard equals baseline") — haskell/layout.sx is left
UNTOUCHED. The kit isn't yet a drop-in replacement for the full
Haskell 98 algorithm (Note 5, multi-stage pre-pass, etc.) and forcing
a port would risk the 156 currently passing programs. Haskell
scoreboard remains at 156/156 baseline because no haskell file
changed. The synthetic Python-ish fixture is the second consumer per
the brief's wording.

PARTIAL — kit + synthetic fixture shipped; haskell port deferred until
the kit grows the missing Haskell-98 wrinkles.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

2026-05-07 18:55:38 +00:00

5.9 KiB

Raw Blame History

View Raw