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dedupe: add the 0-arg transducer arity (jolt-05i2)

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(into [] (dedupe) coll) / (sequence (dedupe) coll) threw an arity error — dedupe
was [coll]-only. Add the 0-arg stateful transducer (tracks [seen? prev] in a
volatile, no sentinel). Re-minted.
This commit is contained in:
Yogthos 2026-06-21 15:42:01 -04:00
parent f6937dd7df
commit 7d0e2f2b61
2 changed files with 168 additions and 156 deletions
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278
host/chez/seed/prelude.ss
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46
jolt-core/clojure/core/20-coll.clj
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@ -591,23 +591,35 @@
;; rand-int: random integer in [0, n). Uses Janet math/random.
;; Eager dedupe of consecutive equal elements (Jolt has no transducer arity yet).
(defn dedupe [coll]
(let [step (fn step [s prev]
(make-lazy-seq
(fn* []
(let [s (seq s)]
(if s
(let [x (first s)]
(if (= x prev)
(coll->cells (step (rest s) prev))
(coll->cells (cons x (step (rest s) x)))))
nil)))))]
(let [s (seq coll)]
(if s
(make-lazy-seq
(fn* [] (coll->cells (cons (first s) (step (rest s) (first s))))))
()))))
;; 0-arg: a stateful transducer (tracks [seen? prev] in a volatile, so no sentinel
;; value is needed). 1-arg: eager dedupe of consecutive equal elements.
(defn dedupe
([]
(fn [rf]
(let [pv (volatile! [false nil])]
(fn
([] (rf))
([result] (rf result))
([result input]
(let [[seen prior] @pv]
(vreset! pv [true input])
(if (and seen (= prior input)) result (rf result input))))))))
([coll]
(let [step (fn step [s prev]
(make-lazy-seq
(fn* []
(let [s (seq s)]
(if s
(let [x (first s)]
(if (= x prev)
(coll->cells (step (rest s) prev))
(coll->cells (cons x (step (rest s) x)))))
nil)))))]
(let [s (seq coll)]
(if s
(make-lazy-seq
(fn* [] (coll->cells (cons (first s) (step (rest s) (first s))))))
())))))
;; Internal helper for {:keys [...]} destructuring over a seq of k/v pairs —
;; canonical Clojure 1.11 shape (core.clj seq-to-map-for-destructuring):