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[Repo Assist] Perf/code: replace ref cells with mutable in ~30 API functions #295

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[Repo Assist] Perf/code: replace ref cells with mutable in ~30 API functions #295

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Perf/code: replace ref cells with mutable in ~30 API functions
github-actions[bot] Apr 1, 2026
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ci: trigger checks
github-actions[bot] Apr 1, 2026
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1 change: 1 addition & 0 deletions RELEASE_NOTES.md
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### 4.11.0

* Code/Performance: Modernised ~30 API functions to use `mutable` local variables instead of `ref` cells (`!`/`:=` operators). Affected: `tryLast`, `tryFirst`, `tryItem`, `compareWithAsync`, `reduceAsync`, `scanAsync`, `pairwise`, `windowed`, `pickAsync`, `tryPickAsync`, `tryFindIndex`, `tryFindIndexAsync`, `threadStateAsync`, `zipWithAsync`, `zipWithAsyncParallel`, `zipWithAsync3`, `allPairs`, `takeWhileAsync`, `takeUntilSignal`, `skipWhileAsync`, `skipWhileInclusiveAsync`, `skipUntilSignal`, `tryTail`, `splitAt`, `toArrayAsync`, `concatSeq`, `interleaveChoice`, `chunkBySize`, `chunkByAsync`, `mergeChoiceEnum`, `distinctUntilChangedWithAsync`, `emitEnumerator`, `removeAt`, `updateAt`, `insertAt`. This eliminates heap-allocated `ref`-cell objects for these variables, reducing GC pressure in hot paths, and modernises the code style to idiomatic F#.
* Performance: `mapiAsync` — replaced `asyncSeq`-builder + `collect` implementation with a direct optimised enumerator (`OptimizedMapiAsyncEnumerator`), eliminating `collect` overhead and bringing per-element cost in line with `mapAsync`. Benchmarks added in `AsyncSeqMapiBenchmarks`.
* Design parity with FSharp.Control.TaskSeq (#277, batch 2):
* Added `AsyncSeq.tryTail` — returns `None` if the sequence is empty; otherwise returns `Some` of the tail. Safe counterpart to `tail`. Mirrors `TaskSeq.tryTail`.
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