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[repo-assist] Improve: replace ref cell with mutable in mergeAll #350

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[repo-assist] Improve: replace ref cell with mutable in mergeAll #350

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1 change: 1 addition & 0 deletions RELEASE_NOTES.md
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@
* Test coverage: Added tests for previously-untested public API functions `AsyncSeq.tryFirst`, `AsyncSeq.firstOrDefault`, `AsyncSeq.zipWithParallel`, `AsyncSeq.combineLatestWithAsync`, and `AsyncSeq.toObservable`. No functional changes.
* Fixed Fable CI build: `Microsoft.Bcl.AsyncInterfaces` was pinned to a specific version (`10.0.7`) that was older than the version resolved transitively via `System.Threading.Channels`, causing a `NU1605` package downgrade error that made Fable's project cracker fail during `dotnet fable`. The reference now uses `Version="*"` (matching `System.Threading.Channels`) so both resolve consistently. (#334)
* Tests: Added comprehensive tests for `AsyncSeq.zapp`, `AsyncSeq.zappAsync`, and `AsyncSeq.compareWithAsync`, which previously had no dedicated test coverage.
* Performance: Replaced the last remaining `ref` cell in `AsyncSeq.mergeAll`'s internal counter with a direct `mutable` local, matching the `ref`-to-`mutable` modernisation already applied elsewhere in the codebase. Eliminates a per-call heap allocation of a `Ref<int>` wrapper; no behavioral change.

### 4.17.0

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6 changes: 3 additions & 3 deletions src/FSharp.Control.AsyncSeq/AsyncSeq.fs
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Expand Up @@ -2682,8 +2682,8 @@ module AsyncSeq =
for i in 0 .. ss.Length - 1 do
let! task = Async.StartChildAsTask (ies.[i].MoveNext())
do tasks.[i] <- task
let fin = ref n
while fin.Value > 0 do
let mutable fin = n
while fin > 0 do
let! ti = Task.WhenAny (tasks) |> Async.AwaitTask
let i = Array.IndexOf (tasks, ti)
let v = ti.Result
Expand All @@ -2697,7 +2697,7 @@ module AsyncSeq =
| None ->
let t = System.Threading.Tasks.TaskCompletionSource()
tasks.[i] <- t.Task // result never gets set
fin.Value <- fin.Value - 1
fin <- fin - 1
}

let combineLatestWithAsync (f:'a -> 'b -> Async<'c>) (source1:AsyncSeq<'a>) (source2:AsyncSeq<'b>) : AsyncSeq<'c> =
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