(partition-all n) and (partition-by f) now return stateful transducers, so they
compose with into/sequence/transduce/comp (previously errored "called with 1
argument, expected 2"). Both buffer a window, emit on boundary, flush a partial
trailing window in the completion arity, and honor `reduced` (early stop drops
the in-progress window, no extra trailing partition) — matching Clojure.
partition-all: td-partition-all in core.janet (Janet, alongside the other td-*),
core-partition-all made variadic. partition-by: transducer arity added to the
overlay defn in Clojure with volatiles (stays with its lazy collection arity).
Gate: conformance 253x3 (+4 transducer cases incl comp + reduced), lazy-infinite
44/44, fixpoint, self-host, specs+unit green.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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