Phase 5: true laziness — lazy transformers + deadlined harness
jolt-c09 (partial, Steps 0–2d complete).
Lazy combinator layer (Step 1):
- lazy-cons: build a LazySeq cell from val + rest-thunk (phm.janet)
- lazy-from: coerce any seqable to lazy view without forcing (core.janet)
- core-seq: check ls-first emptiness, not ls-seq realization (core.janet)
Lazy transformers (Steps 2a–2d):
Converted in Janet core.janet (lazy branches preserving transducer arities):
drop-while, interpose, distinct, partition, partition-all,
keep, keep-indexed, map-indexed, take-nth
Moved to Clojure overlay (jolt-core):
interleave (20-coll.clj) — lazy multi-arity, matches Clojure
mapcat (10-seq.clj) — transducer arity + standard (apply concat (apply map f colls))
Safety net (Step 0):
test/support/lazy-eval.janet — subprocess worker for Clojure eval
test/integration/lazy-infinite-test.janet — deadlined harness (os/spawn + 5s)
Multi-input map/mapcat tests (Step 2d):
sequences-spec.janet +9 tests, verified against Clojure/CLJS references
Gates:
lazy-infinite: 18/18 (mapcat on infinite inputs hangs — apply forces, needs Step 4)
conformance: 229/229 ×3 (interpret/compile/self-host)
specs: 32/32 files, 0 failures
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