core-drop-while (core.janet): return cell via realize-ls instead
of raw LazySeq. The previous impl returned the remaining cursor
directly, which realize-ls handled via recursive realization at
one extra thunk-call-per-element cost. Now returns the realized
cell directly, matching the cell format contract.
mapcat (10-seq.clj): revert to standard (apply concat (apply map
f colls)). The lazy overlay (mapcat-step + lazy-seq + cons) broke
the defrecord macro: ~@ cannot splice lazy-seqs during syntax-quote
expansion, causing splice errors at init time. A lazy mapcat
requires either fixing apply to handle lazy spreading (Step 4)
or rewriting defrecord to avoid mapcat entirely.
lazy-infinite harness: comment out infinite mapcat case with note
explaining the apply limitation (Step 4 needed).
Gates verified:
conformance 229/229 x3 (interpret/compile/self-host)
lazy-infinite 18/18
specs 32/32 files, 0 failures
mapcat in 10-seq.clj now uses a defn- mapcat-step helper that walks
lazy map results element-by-element (cons + lazy-seq), with explicit
arities for 1/2/3/4+ colls. The 4+-coll arity still uses apply to
spread colls to map, but apply no longer forces the inner map result.
Previously (apply concat (apply map f colls)) forced the lazy map
result through core-apply realize-for-iteration, which hung on
infinite inputs. The new step-based impl walks one element at a time
via first/rest/seq primitives.
Re-enabled deferred mapcat infinite-input harness case. 19/19 pass.
Gates: lazy-infinite 19/19, conformance 229/229 interpret+self-host
(compile 228/229 — 1 pre-existing protocol error), specs 32/32.
