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Chez Phase 1 (increment 3q): multimethod dispatch + late-bind

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host/chez/multimethods.ss implements the multimethod runtime: defmulti/defmethod
expand to defmulti-setup/defmethod-setup calls (+ get-method/methods/
remove-method/prefer-method/prefers). A jolt-multifn record carries its dispatch
fn and a jolt=-keyed method table; jolt-invoke dispatches it (exact match, then
isa?/hierarchy with prefer-method, then :default), reusing the overlay's
isa?/derive/make-hierarchy. The multifn's ns comes from a runtime chez-current-ns
(default user; the prelude load sets clojure.core for print-method/print-dup).

Two emit-side changes were needed:
- late-bind (:late-bind-unresolved? ctx flag, default OFF): defmulti expands to a
  bare-symbol setup call, so the analyzer doesn't intern the name and a forward
  reference '(area ...)' after '(defmulti area ...)' in one form was 'Unable to
  resolve symbol'. The strict compiler punts these to the interpreter; the Chez
  back end has none, so the flag lowers an unresolved symbol to a var-ref against
  the compile ns (open-world -e semantics). Set only by the Chez make-ctx /
  jolt-chez; the main compiler keeps strict resolution (host_iface late-bind?
  defaults nil).
- a :var call head now routes through jolt-invoke, since a late-bound var can hold
  a multifn (or keyword/coll IFn), not just a procedure. Transparent for
  procedures; the hot self-recursive call is a :local known-proc, stays direct.

Class-based dispatch ((class x)/String) deferred (needs deftype/class subsystem).

Parity 1506 -> 1530/2497, 0 new divergences. emit-test 302/302. Full janet gate
green (the analyzer flag is off there; suite flakiness under parallel load only).
This commit is contained in:
Yogthos 2026-06-18 01:24:01 -04:00
parent e51cc2e47e
commit 02139af0a1
10 changed files with 279 additions and 8 deletions
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11
src/jolt/host_iface.janet
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@ -171,6 +171,14 @@
(ns-intern (ctx-find-ns ctx ns-name) nm)
nil)
# Open-world (late-binding) analysis: when set on the ctx env, an unresolved
# symbol emits a var-ref against the compile ns (resolved at runtime) instead of
# punting to the interpreter. The Chez back end (host/chez/driver) sets it: it has
# no interpreter to punt to, and a forward reference to a runtime-interned var
# (e.g. defmulti's setup call) must lower to a var-deref. Off everywhere else, so
# the normal compiler keeps its strict 'Unable to resolve symbol' behavior.
(defn h-late-bind? [ctx] (truthy? (get (ctx :env) :late-bind-unresolved?)))
# ---------------------------------------------------------------------------
# Installation: bind these fns as vars in the `jolt.host` namespace so jolt-core
# can call them. Idempotent per context.
@ -270,7 +278,8 @@
"host-intern!" h-intern!
"inline-enabled?" h-inline-enabled? "inline-ir" h-inline-ir
"record-type?" h-record-type? "form-position" h-form-position
"record-ctor-key" h-record-ctor-key "record-shapes" h-record-shapes})
"record-ctor-key" h-record-ctor-key "record-shapes" h-record-shapes
"late-bind?" h-late-bind?})
(defn install! [ctx]
(def ns (ctx-find-ns ctx "jolt.host"))