perf: O(N²) → O(N) upvalue collection in closure handler#154
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davydog187 merged 1 commit intomainfrom Feb 27, 2026
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Replace list-append accumulation (`cells ++ [ref]`) with list-prepend (`[ref | cells]`) followed by a single `Enum.reverse/1` at the end of the reduce. Each `++` was O(N) in the current list length, making the full collection O(N²) for N upvalue descriptors. Prepend is O(1), so the full collection is now O(N). Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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Summary
Replace list-append accumulation (
cells ++ [ref]) with list-prepend ([ref | cells]) followed by a singleEnum.reverse/1in the:closureinstruction handler.Each
++was O(N) in the current accumulated list length, making the full upvalue collection O(N²) for N upvalue descriptors. Prepend is O(1), so the collection is now O(N).In practice closures rarely have more than a handful of upvalues, but this removes a pathological cost for any closure that captures many variables and is created repeatedly (e.g. inside a tight loop).
Test plan
🤖 Generated with Claude Code