A type-aware audit (~190 collection expressions vs reference Clojure) found four
divergences the corpus missed — value-equality (= [0 1] '(0 1)) hides type and
laziness differences. Fixed, with type-predicate + over-infinite corpus rows that
pin them.
- partition-all [n coll] built vector chunks; JVM chunks are seqs. (The [n step
coll] arity was already correct, as is the partition-all transducer, whose
chunks are vectors in JVM too.) Now builds seq chunks.
- replace always returned a vector (mapv) and was eager; JVM is type-preserving —
a vector maps to a vector, any other seqable to a lazy seq.
- sequence eagerly realized its source (into-xform), so (first (sequence (map inc)
(range))) hung. Rewrote as a transformer iterator: pull one input at a time,
buffer the step outputs, emit lazily, run the completion to flush a stateful
xform. eduction builds on it (lazy, no longer an eager vector).
- mapcat and (apply concat coll-of-colls) hung over an infinite source because
jolt-apply seq->lists the trailing arg and mapcat seq->lists the map result.
Added lazy-concat-seq (lazily flatten a seq of colls); mapcat uses it directly,
and apply special-cases concat (its result is lazy) to route through it.
Docs: a cross-cutting return-type + laziness contract in docs/spec/09-core-library;
SPEC.md notes that = masks type/laziness so they need predicate / over-infinite
rows. EBNF is reader syntax only — unaffected.
Seed change (partition-all/replace/eduction are clojure.core overlay) -> re-mint;
selfhost holds. make test + shakesmoke + buildsmoke green, 0 new divergences.
Co-authored-by: Yogthos <yogthos@gmail.com>
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