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core: migrate partition-all to the Clojure overlay (minimal realization)

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Resolves the deferred partition-all port (jolt-yo3). The earlier CLJ attempt via
lazy take/drop over-realized vs the Janet pstep, tripping the §6.3 laziness
counter. The collection arities now realize EXACTLY n per chunk with a first/rest
loop and continue from the advanced cursor (no re-drop), so (take 3 (partition-all
2 (map counting (range)))) realizes exactly 6 — matching minimal realization in
both interpret and compile modes. Keeps transducer + [n coll] + [n step coll]
arities. letfn-bound recursion sidesteps the compile-mode multi-arity closure bug
(jolt-zxw), like keep-indexed/map-indexed.

Removed from the Janet seed: core-partition-all + its binding + the now-dead
td-partition-all helper (the CLJ version carries its own transducer arity).

Gate: conformance 262x3, lazy-infinite 44/44 (incl the §6.3 partition-all
counter), clojure-test-suite 4004/66, fixpoint, self-host, specs+unit green.
This commit is contained in:
Yogthos 2026-06-08 23:43:00 -04:00
parent 2c31a9e3bc
commit cab1a75b75
2 changed files with 39 additions and 38 deletions
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41
jolt-core/clojure/core/40-lazy.clj
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@ -100,7 +100,40 @@
(lazy-seq (cons x (iterate f (f x)))))
;; partition-all stays in the Janet seed for now (core-partition-all): it already
;; has the transducer + collection arities (jolt-cru), and a CLJ port realizes a
;; different (non-minimal) element count via take/drop than the Janet one,
;; tripping the §6.3 laziness counters + a suite file. Ported separately.
;; --- partition-all --- (transducer + [n coll] + [n step coll])
;; The collection arities realize EXACTLY n per chunk via a first/rest loop and
;; continue from the advanced cursor (not a re-drop), so they realize minimally
;; — matching the Janet pstep the §6.3 laziness counters were written against.
;; letfn-bound `go` (not arity-direct recursion) sidesteps the compile-mode
;; multi-arity closure-capture bug (jolt-zxw), as keep-indexed/map-indexed do.
(defn partition-all
([n]
(fn [rf]
(let [a (volatile! [])]
(fn
([] (rf))
([result]
(let [result (if (zero? (count @a))
result
(let [v @a] (vreset! a []) (unreduced (rf result v))))]
(rf result)))
([result input]
(vswap! a conj input)
(if (= n (count @a))
(let [v @a] (vreset! a []) (rf result v))
result))))))
([n coll]
(letfn [(go [s]
(lazy-seq
(when (seq s)
(loop [i 0 chunk [] cur s]
(if (and (< i n) (seq cur))
(recur (inc i) (conj chunk (first cur)) (rest cur))
(cons chunk (go cur)))))))]
(go coll)))
([n step coll]
(letfn [(go [s]
(lazy-seq
(when (seq s)
(cons (take n s) (go (nthrest s step))))))]
(go coll))))