builtins.groupBy: Drop ValueVectorMap#536
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Apply the same optimization to builtins.groupBy as to builtins.zipAttrsWith (162a34378c): instead of accumulating the groups in a std::map<Symbol, ValueVector> with traceable_allocator - which costs a GC_MALLOC_UNCOLLECTABLE() per distinct name plus traceable growth allocations for every per-group vector, all taking the global GC allocation lock - collect the (name, value) pairs into a plain std::vector and group them by stable-sorting on the name. The vector doesn't need to be visible to the GC since the values it points to are kept alive by the list in args[1] for the duration of the call. The shared machinery (the NameValue type, sorting/counting the names, and iterating over the per-name runs) is factored out into helpers used by both primops. This removes the last user of ValueVectorMap, so drop that typedef. Assisted-by: Claude Fable 5 <noreply@anthropic.com>
edolstra
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📝 WalkthroughWalkthroughThis change refactors ChangesGrouping helper refactor
Estimated code review effort: 2 (Simple) | ~15 minutes Related PRs: None identified. Suggested labels: refactor, libexpr Suggested reviewers: None identified. 🚥 Pre-merge checks | ✅ 5✅ Passed checks (5 passed)
✨ Finishing Touches📝 Generate docstrings
🧪 Generate unit tests (beta)
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edolstra
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cole-h
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Jul 6, 2026
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Motivation
Apply the same optimization to
builtins.groupByas tobuiltins.zipAttrsWithin #535, and factor out some shared code. This removes the need for theValueVectorMap.Context
Summary by CodeRabbit