Lift map/flt/fld closure-bind to native VM dispatch (PR A of ILO-45)#619
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PR A of ILO-45. Adds three new compiler arms in src/vm/mod.rs that emit native OP_CALL_DYN loops for the closure-bind ctx variants: - map fn ctx xs argc=2, per-iter call(item, ctx) - flt fn ctx xs argc=2, per-iter call(item, ctx), bool typecheck + LISTAPPEND - fld fn ctx xs init argc=3, per-iter call(acc, item, ctx) Removes the three arms from is_tree_bridge_eligible. Cranelift JIT and AOT inherit via the existing OP_CALL_DYN codegen (jit_call_dyn), so this fixes the closure-bind gap on JIT that examples/closure-bind.@ had been engine-skipping since PR 3c. Reg layout mirrors the existing 2-arg HOF arms: res + N contiguous arg slots, with the same contiguity assertions. Closure captures auto-append after the user args via the dispatcher's closure path at mod.rs:9785, matching the tree-walker's [item, ctx, ...captures] / [acc, item, ctx, ...captures] call_args order at runtime/mod.rs:5737 / :5958. srt 3 and rsrt 3 still bridge pending PR B's finalizer-opcode extension. ct 2/3 and rsrt 2 are PR C. Test plan: examples/closure-bind.@ now exercises map/flt/fld closure-bind across default / --vm / --jit. All four assertions match (main, prices- demo, above-demo, weighted-demo). Full suite green: 3348 unit tests pass.
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This was referenced May 22, 2026
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Summary
PR A of ILO-45 — first slice of the actual tree-walker eval-loop deletion. Lifts
map fn ctx xs/flt fn ctx xs/fld fn ctx xs initfrom tree-bridge dispatch to native VM dispatch viaOP_CALL_DYN. Cranelift inherits via the existingjit_call_dynhelper.The bridge for these three HOFs called
eval_body(the tree-walker's expression evaluator) per-element to run the user's closure-bind callback. After this PR they dispatch natively. Three down, five HOFs (srt 3,rsrt 2,rsrt 3,ct 2,ct 3) plus the non-HOF bridge entries to go before the eval loop can actually be deleted.Why now
PR #613 shipped the user-visible promise (no
Engine::Tree, no--run-tree, runtime renamed) but kepteval_bodyalive because the bridge for closure-bind HOFs called into it. This PR starts unwinding that dependency.ILO-234's "bridge is the right abstraction" framing held for non-HOF builtins (regex / fmt / fs / crypto / calendar — cheap round-trip, no eval involvement). For HOFs the round-trip goes through
call_function→eval_body, which is the load-bearing path that keeps the tree-walker alive. Lifting these natively is the only way to actually delete it.What's in the diff
Single commit, two files:
src/vm/mod.rscompile_call:(Builtin::Map, 3),(Builtin::Flt, 3),(Builtin::Fld, 4). Each emitsOP_FOREACHPREP/OP_CALL_DYN/OP_LISTAPPEND(or fld's accumulator refresh) in the same shape as the existing 2-arg arms. Reg layout: res + 2 or 3 contiguous arg slots. flt 3 keeps the bool typecheck + WRAPERR/PANIC_UNWRAP error path from flt 2.is_tree_bridge_eligible: dropped the three entries;Srt, 3andRsrt, 3retained pending PR B.examples/closure-bind.@engine-skip: jitdirective (closure-bind HOFs now work on JIT)above-demo(flt 3) andweighted-demo(fld 4) with assertable outputCranelift inherits via the existing OP_CALL_DYN codegen — no Cranelift changes needed.
Test plan
cargo test --release --features cranelift— full suite green, 3348+ unit tests pass, no regressionsexamples/closure-bind.@runs identically across default /--vm/--jitfor all four demo functionscargo test --release --features cranelift --test examples_enginespassesFollow-ups
srt 3/rsrt 2/rsrt 3— needsOP_SRT_BY_KEYdesc-flag extension or newOP_RSRT_BY_KEYct 2/ct 3— needs finalizer or inline counter loopeval_bodyreachability and lift any that need iteval_body/eval_stmt/eval_expr/Env/trampoline/ACTIVE_AST_PROGRAM(headline LoC win)