Closed-world (optimization mode): after a unit loads, infer-unit! runs a
whole-unit fixpoint over the call graph and recompiles. A fn's param types are
the lub of its in-unit call-site arg types; its return type is the lub of its
tail positions; iterated to a least fixpoint. Param types are RECOMPUTED FRESH
each iteration (not accumulated) because :any is the lattice top — joining an
early-iteration :any would poison the result permanently. Closures inherit the
enclosing tenv so captured locals keep their types (their own params shadow to
:any). A fn whose var escapes as a VALUE keeps :any params (its callers aren't
all visible). Each fn is then re-inferred with its param types seeded and
re-emitted; recompiled bodies are semantically identical, so correctness holds
regardless of order. Sound under source distribution + whole-program compile
(the consumer compiles all call sites together).
Plumbing: the portable pass (jolt.passes) gained inter-procedural primitives —
set-rtenv!, infer-body (types a body, collects its call sites), reinfer-def
(seeds param types), and escape tracking. The back end stashes each
single-fixed-arity defn's :def IR (:infer-ir); the evaluator triggers
infer-unit! after a unit loads (via an env hook, opt mode only).
Result and honest finding: the fixpoint correctly types scalar-flowing params
(ray-cast/hit-all/hit-sphere all get the ray param as :struct-map, no hint),
but the ray tracer does NOT speed up — its dominant lookups are on `hittable`,
the element of the `hittables` vector threaded through `reduce`, which stays
:any. Typing it needs collection-element types (vector<struct>) plus HOF-element
awareness (knowing reduce applies the closure to elements), which is beyond
inter-procedural param inference. The explicit ^:struct hint reaches it (it
types the reduce closure param directly), which is why the hinted run is 1.22x.
Verified: conformance 335/335 x3, full jpm test; new type-infer-phase1-test
pins the fixpoint, the escape gate, the seeded re-inference, and correctness.
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