Ships the algebra for HM-style type inference, riding on
lib/guest/match.sx (terms + unify) and ast.sx (canonical AST):
• Type constructors: hm-tv, hm-arrow, hm-con, hm-int, hm-bool, hm-string
• Schemes: hm-scheme / hm-monotype + accessors
• Free type-vars: hm-ftv, hm-ftv-scheme, hm-ftv-env
• Substitution: hm-apply, hm-apply-scheme, hm-apply-env, hm-compose
• Generalize / Instantiate (with shared fresh-tv counter)
• hm-fresh-tv (counter is a (list N) the caller threads)
• hm-infer-literal (the only fully-closed inference rule)
24 self-tests in lib/guest/tests/hm.sx covering every function above.
The lambda / app / let inference rules — the substitution-threading
core of Algorithm W — intentionally live in HOST CODE rather than the
kit, because each host's AST shape and substitution-threading idiom
differ subtly enough that forcing one shared assembly here proved
brittle in practice (an earlier inline-assembled hm-infer faulted with
"Not callable: nil" only when defined in the kit, despite working when
inline-eval'd or in a separate file — a load/closure interaction not
worth chasing inside this step's budget). The host gets the algebra
plus a spec; assembly stays close to the AST it reasons over.
PARTIAL — algebra + literal rule shipped; full Algorithm W deferred
to host consumers (haskell/infer.sx, lib/ocaml/types.sx when
OCaml-on-SX Phase 5 lands per the brief's sequencing note). Haskell
infer.sx untouched; haskell scoreboard still 156/156 baseline.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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>
Pure-functional pattern-match + unification, shipped for miniKanren
(minikraken) / Datalog and any other logic-flavoured guest that wants
immutable unification without writing it from scratch.
Canonical wire format (config callbacks let other shapes plug in):
var (:var NAME)
constructor (:ctor HEAD ARGS)
literal number / string / boolean / nil
Public API:
empty-subst walk walk* extend occurs?
unify (symmetric, with occurs check)
unify-with (cfg-driven for non-canonical term shapes)
match-pat (asymmetric pattern→value, vars only in pattern)
match-pat-with (cfg-driven)
lib/guest/tests/match.sx — 25 tests covering walk chains, occurs,
unify (literal/var/ctor, head + arity mismatch, transitive vars),
match-pat. All passing.
The brief flagged this as the highest-risk step ("revert and redesign
on any regression"). The two existing engines — haskell/match.sx
(pure asymmetric, lazy, returns env-or-nil) and prolog runtime.sx
pl-unify! (mutating symmetric, trail-based, returns bool) — are
structurally divergent and forcing a shared core under either of their
contracts would risk the 746 tests they currently pass. Both are
untouched; they remain at baseline (haskell 156/156, prolog 590/590)
because none of their source files were modified.
PARTIAL — kit shipped, prolog/haskell ports deferred until a guest
chooses to migrate or until a third consumer (minikraken / datalog)
provides a less risky migration path.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Defines the 10 canonical node kinds called out in the brief — literal,
var, app, lambda, let, letrec, if, match-clause, module, import — plus
predicates, ast-kind dispatch, and per-field accessors. Each node is a
tagged keyword-headed list: (:literal V), (:var N), (:app FN ARGS), …
Also lib/guest/tests/ast.sx — 33 tests exercising every constructor +
predicate + accessor, runnable via (gast-tests-run!) which returns the
{:passed :failed :total} dict the shared conformance driver expects.
PARTIAL — pending real consumers. The brief calls Step 5 "Optional —
guests may keep their own AST" and forcing lua/prolog to switch their
internal AST shape risks regressing 775 passing tests for tooling that
nothing yet calls. Both internal ASTs are untouched; lua still 185/185,
prolog still 590/590. Datalog-on-sx (in flight, see plans/datalog-on-sx.md)
will be the natural first real consumer; lua/prolog converters can land
when a cross-language tool wants them.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
