Extends the inference lattice with a parametric vector type {:vec ELEM} and
threads element types through the program:
- vector literals, conj/into, and range produce element-typed vectors;
- reduce/map/mapv/filter/filterv seed their closure's element (and reduce's
accumulator) param, so a lookup inside the closure over a vector-of-structs
specializes (the HOF-element-awareness piece);
- a var reference carries a VALUE type — a fn var is :truthy (non-nil, sealed
root), a def var carries its inferred init type (e.g. a color table is
{:vec :struct-map}); element-returning fns (rand-nth/first/nth/...) yield the
collection's element type. These let the dynamically-built scene's sphere
maps type as structs.
The inter-procedural fixpoint now also infers non-fn def value types, and the
recompile re-emits the WHOLE unit callee-first (reverse-topological) so a
caller re-embeds its recompiled, now-specialized callees and a call site
compiled after the pass links the whole chain.
Result on the ray tracer (no hints): the chain closes — hittables infers to
{:vec :struct-map}, hit-sphere's hittable param to :struct-map — and the render
goes 13.1s -> 12.8s. That is only ~3%, far short of the explicit hint's 1.22x.
The remaining gap is nested field access: a lookup RESULT like (:direction ray)
is :any, so (:r (:direction ray)) stays guarded, and the vec3 fns (called with
such values) can't be typed struct. The hint asserts the vec3 params directly
and propagates through inlining; matching it needs field-shape types
(ray.direction : vec3, vec3.r : number) — a structural extension (Phase 4).
Sound: a seeded full render produces an identical checksum (1915337);
conformance 335/335 x3 and the full jpm test pass; type-infer-phase3-test pins
the element-typing + HOF mechanism. Phase 2 (vector nth/count specialization)
was deprioritized — it is orthogonal to this benchmark.
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