jolt/host/chez/lazy-bridge.ss
Yogthos fc6551f877 Chez Phase 2 (inc M): dynamic var binding (jolt-2o7x)
Add the dynamic-binding cluster on the Chez RT: a per-thread binding stack
(host/chez/dyn-binding.ss) backing binding / with-bindings* / var-set /
thread-bound? / with-local-vars / with-redefs / bound-fn* /
get-thread-bindings / alter-var-root + the __local-var seam.

Frames are stored innermost-first as identity-keyed alists of mutable
(cell . value) pairs, so var-set updates the current binding in place. The
two var-read paths — var-deref (compiled code) and jolt-var-get (var-get /
deref on a cell) — are chained onto the stack so a `binding` frame is seen
by every read, with a fast path when the stack is empty. var-cells now hash
by ns/name so a var works as a map key (with-redefs builds (hash-map (var f)
v); get-thread-bindings returns a var-keyed map).

Fix a latent bug exposed once with-in-str could bind *in*: seq? didn't
recognize a lazy-seq. predicates.ss's jolt-seq? predates the lazyseq record,
and unlike the native-op dispatchers it's reached via var-deref, so the
patch must re-def-var! the var, not just set! the top-level binding.

Note: with-bindings* over a hash-map literal now returns the correct Clojure
value where the seed returns a stale one — the seed's PHM can't find a var
key (which is why its `binding` uses array-map); on Chez frames look up by
cell identity.

Prelude corpus parity 1972 -> 2000, floor raised. Gate: _dynbind 24/24,
prelude corpus 0 divergences, full jpm test, conformance 355x3.
2026-06-18 18:29:55 -04:00

87 lines
4.6 KiB
Scheme

;; lazy-seq bridge (jolt-cf1q.3, jolt-dmw9) — make-lazy-seq / coll->cells.
;;
;; The `lazy-seq` macro (00-syntax.clj) expands to
;; (make-lazy-seq (fn* [] (coll->cells (do body))))
;; and `lazy-cat` to (concat (lazy-seq c) ...). make-lazy-seq / coll->cells are
;; seed natives (src/jolt/lazyseq.janet) with no Chez shim, so EVERY overlay fn
;; built on lazy-seq — repeat / iterate / cycle / dedupe / take-nth / keep /
;; interpose / reductions / tree-seq (-> flatten) / lazy-cat — resolved the call
;; to jolt-nil and hit the apply-jolt-nil crash bucket.
;;
;; Bridge to the cseq model (seq.ss): a `jolt-lazyseq` is a deferred seq — a 0-arg
;; thunk that, when forced once, yields a seq (cseq | nil). coll->cells coerces the
;; body result to a seq (= jolt-seq), so the thunk already returns a seq; jolt-seq
;; is extended to force a lazyseq. The one trap: (cons x (a-lazy-seq)) must NOT
;; force the tail (else (repeat x) = (lazy-seq (cons x (repeat x))) loops forever),
;; so jolt-cons defers a lazyseq tail into a lazy cseq cell.
;;
;; Loaded LAST (after host-table.ss): %ls-seq then captures the fully-extended
;; jolt-seq (sorted-aware), so a lazy body returning a sorted coll still seqs.
(define-record-type jolt-lazyseq
(fields (mutable thunk) (mutable val) (mutable realized?))
(nongenerative jolt-lazyseq-v1))
(define (jolt-make-lazy-seq thunk) (make-jolt-lazyseq thunk jolt-nil #f))
;; force once and memoize. The thunk is (fn [] (coll->cells body)); coll->cells
;; already coerced the body to a seq (cseq | nil) via the live jolt-seq, so the
;; result needs no further coercion (a nested lazyseq was forced by coll->cells).
(define (force-lazyseq x)
(if (jolt-lazyseq-realized? x)
(jolt-lazyseq-val x)
(let ((r (jolt-invoke (jolt-lazyseq-thunk x))))
(jolt-lazyseq-val-set! x r)
(jolt-lazyseq-realized?-set! x #t)
(jolt-lazyseq-thunk-set! x #f)
r)))
;; coll->cells: coerce the body result to the cell representation = a seq | nil.
(define (jolt-coll->cells c) (jolt-seq c))
;; extend jolt-seq to force a lazyseq (a lazyseq is seqable -> its realized seq).
(define %ls-seq jolt-seq)
(set! jolt-seq (lambda (x) (if (jolt-lazyseq? x) (force-lazyseq x) (%ls-seq x))))
;; (cons x lazyseq): keep the tail lazy — force it only when the cseq cell is
;; walked, so an infinite (repeat/iterate/cycle) stays productive.
(define %ls-cons jolt-cons)
(set! jolt-cons (lambda (x coll)
(if (jolt-lazyseq? coll)
(cseq-lazy x (lambda () (force-lazyseq coll)))
(%ls-cons x coll))))
;; A lazyseq is a NEW value type, so the dispatchers that DON'T route through
;; jolt-seq must learn it or a raw (unrealized) lazyseq escapes — e.g. the corpus
;; compares (= [1 3 5] (take-nth 2 …)) against the raw lazyseq, and jolt=2 would
;; see an unknown type and return false. Recognizing it as sequential is enough
;; for equality + hash (seq=? / seq-hash coerce via jolt-seq); count / empty? /
;; nth / the printers don't, so coerce those explicitly.
(define %ls-sequential? jolt-sequential?)
(set! jolt-sequential? (lambda (x) (or (jolt-lazyseq? x) (%ls-sequential? x))))
(define %ls-count jolt-count)
(set! jolt-count (lambda (x) (if (jolt-lazyseq? x) (%ls-count (jolt-seq x)) (%ls-count x))))
(define %ls-empty? jolt-empty?)
(set! jolt-empty? (lambda (x) (if (jolt-lazyseq? x) (%ls-empty? (jolt-seq x)) (%ls-empty? x))))
(define %ls-nth jolt-nth)
(set! jolt-nth (case-lambda
((coll i) (if (jolt-lazyseq? coll) (%ls-nth (jolt-seq coll) i) (%ls-nth coll i)))
((coll i d) (if (jolt-lazyseq? coll) (%ls-nth (jolt-seq coll) i d) (%ls-nth coll i d)))))
(define %ls-pr-str jolt-pr-str)
(set! jolt-pr-str (lambda (x) (if (jolt-lazyseq? x) (%ls-pr-str (jolt-seq x)) (%ls-pr-str x))))
(define %ls-pr-readable jolt-pr-readable)
(set! jolt-pr-readable (lambda (x) (if (jolt-lazyseq? x) (%ls-pr-readable (jolt-seq x)) (%ls-pr-readable x))))
(define %ls-str-render-one jolt-str-render-one)
(set! jolt-str-render-one (lambda (x) (if (jolt-lazyseq? x) (%ls-str-render-one (jolt-seq x)) (%ls-str-render-one x))))
;; seq? — a lazy seq IS a seq (predicates.ss's jolt-seq? predates the lazyseq
;; record). Unlike the native-op dispatchers above (called via a direct top-level
;; reference, so the set! is enough), seq? is reached through var-deref, which
;; reads the var-cell root — so the patched closure must be re-def-var!'d, not just
;; set!. (Exposed once dynamic binding let with-in-str/line-seq reach seq?.)
(define %ls-seq? jolt-seq?)
(set! jolt-seq? (lambda (x) (or (jolt-lazyseq? x) (%ls-seq? x))))
(def-var! "clojure.core" "seq?" jolt-seq?)
(def-var! "clojure.core" "make-lazy-seq" jolt-make-lazy-seq)
(def-var! "clojure.core" "coll->cells" jolt-coll->cells)