e434a7d352
The lazy-seq macro expands to (make-lazy-seq (fn* [] (coll->cells body))) and lazy-cat to (concat (lazy-seq c) ...); both seed natives were nil on the prelude, so every overlay fn built on lazy-seq — repeat/iterate/ cycle/dedupe/take-nth/keep/interpose/reductions/map-indexed/distinct/ interleave/tree-seq(->flatten)/partition-all/lazy-cat — hit apply-jolt-nil. lazy-bridge.ss bridges to the cseq model: a jolt-lazyseq is a deferred seq forced once by an extended jolt-seq; jolt-cons defers a lazyseq tail so an infinite (repeat/iterate/cycle) stays lazy. A lazyseq is a new value type, so the dispatchers that don't route through jolt-seq learn it (sequential? for =/hash, plus count/empty?/nth/printers) or a raw unrealized lazyseq escapes — the corpus compares (= [1 3 5] (take-nth …)) against it directly. seq.ss: jolt-concat is now fully lazy (the rest isn't forced until the first coll is exhausted), so a self-referential lazy-cat — fib = (lazy-cat [0 1] (map + (rest fib) fib)) — no longer memoizes its tail as empty by reading fib before its def binds. Prelude parity 1837 -> 1886, 0 new divergences. Floor raised to 1886.
78 lines
4.1 KiB
Scheme
78 lines
4.1 KiB
Scheme
;; lazy-seq bridge (jolt-cf1q.3, jolt-dmw9) — make-lazy-seq / coll->cells.
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;;
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;; The `lazy-seq` macro (00-syntax.clj) expands to
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;; (make-lazy-seq (fn* [] (coll->cells (do body))))
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;; and `lazy-cat` to (concat (lazy-seq c) ...). make-lazy-seq / coll->cells are
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;; seed natives (src/jolt/lazyseq.janet) with no Chez shim, so EVERY overlay fn
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;; built on lazy-seq — repeat / iterate / cycle / dedupe / take-nth / keep /
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;; interpose / reductions / tree-seq (-> flatten) / lazy-cat — resolved the call
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;; to jolt-nil and hit the apply-jolt-nil crash bucket.
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;;
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;; Bridge to the cseq model (seq.ss): a `jolt-lazyseq` is a deferred seq — a 0-arg
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;; thunk that, when forced once, yields a seq (cseq | nil). coll->cells coerces the
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;; body result to a seq (= jolt-seq), so the thunk already returns a seq; jolt-seq
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;; is extended to force a lazyseq. The one trap: (cons x (a-lazy-seq)) must NOT
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;; force the tail (else (repeat x) = (lazy-seq (cons x (repeat x))) loops forever),
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;; so jolt-cons defers a lazyseq tail into a lazy cseq cell.
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;;
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;; Loaded LAST (after host-table.ss): %ls-seq then captures the fully-extended
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;; jolt-seq (sorted-aware), so a lazy body returning a sorted coll still seqs.
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(define-record-type jolt-lazyseq
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(fields (mutable thunk) (mutable val) (mutable realized?))
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(nongenerative jolt-lazyseq-v1))
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(define (jolt-make-lazy-seq thunk) (make-jolt-lazyseq thunk jolt-nil #f))
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;; force once and memoize. The thunk is (fn [] (coll->cells body)); coll->cells
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;; already coerced the body to a seq (cseq | nil) via the live jolt-seq, so the
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;; result needs no further coercion (a nested lazyseq was forced by coll->cells).
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(define (force-lazyseq x)
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(if (jolt-lazyseq-realized? x)
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(jolt-lazyseq-val x)
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(let ((r (jolt-invoke (jolt-lazyseq-thunk x))))
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(jolt-lazyseq-val-set! x r)
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(jolt-lazyseq-realized?-set! x #t)
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(jolt-lazyseq-thunk-set! x #f)
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r)))
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;; coll->cells: coerce the body result to the cell representation = a seq | nil.
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(define (jolt-coll->cells c) (jolt-seq c))
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;; extend jolt-seq to force a lazyseq (a lazyseq is seqable -> its realized seq).
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(define %ls-seq jolt-seq)
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(set! jolt-seq (lambda (x) (if (jolt-lazyseq? x) (force-lazyseq x) (%ls-seq x))))
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;; (cons x lazyseq): keep the tail lazy — force it only when the cseq cell is
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;; walked, so an infinite (repeat/iterate/cycle) stays productive.
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(define %ls-cons jolt-cons)
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(set! jolt-cons (lambda (x coll)
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(if (jolt-lazyseq? coll)
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(cseq-lazy x (lambda () (force-lazyseq coll)))
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(%ls-cons x coll))))
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;; A lazyseq is a NEW value type, so the dispatchers that DON'T route through
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;; jolt-seq must learn it or a raw (unrealized) lazyseq escapes — e.g. the corpus
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;; compares (= [1 3 5] (take-nth 2 …)) against the raw lazyseq, and jolt=2 would
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;; see an unknown type and return false. Recognizing it as sequential is enough
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;; for equality + hash (seq=? / seq-hash coerce via jolt-seq); count / empty? /
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;; nth / the printers don't, so coerce those explicitly.
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(define %ls-sequential? jolt-sequential?)
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(set! jolt-sequential? (lambda (x) (or (jolt-lazyseq? x) (%ls-sequential? x))))
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(define %ls-count jolt-count)
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(set! jolt-count (lambda (x) (if (jolt-lazyseq? x) (%ls-count (jolt-seq x)) (%ls-count x))))
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(define %ls-empty? jolt-empty?)
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(set! jolt-empty? (lambda (x) (if (jolt-lazyseq? x) (%ls-empty? (jolt-seq x)) (%ls-empty? x))))
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(define %ls-nth jolt-nth)
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(set! jolt-nth (case-lambda
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((coll i) (if (jolt-lazyseq? coll) (%ls-nth (jolt-seq coll) i) (%ls-nth coll i)))
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((coll i d) (if (jolt-lazyseq? coll) (%ls-nth (jolt-seq coll) i d) (%ls-nth coll i d)))))
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(define %ls-pr-str jolt-pr-str)
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(set! jolt-pr-str (lambda (x) (if (jolt-lazyseq? x) (%ls-pr-str (jolt-seq x)) (%ls-pr-str x))))
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(define %ls-pr-readable jolt-pr-readable)
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(set! jolt-pr-readable (lambda (x) (if (jolt-lazyseq? x) (%ls-pr-readable (jolt-seq x)) (%ls-pr-readable x))))
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(define %ls-str-render-one jolt-str-render-one)
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(set! jolt-str-render-one (lambda (x) (if (jolt-lazyseq? x) (%ls-str-render-one (jolt-seq x)) (%ls-str-render-one x))))
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(def-var! "clojure.core" "make-lazy-seq" jolt-make-lazy-seq)
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(def-var! "clojure.core" "coll->cells" jolt-coll->cells)
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