refactor(Batching)!: Relax arbitrary arrays constraint

Author: bartelink

src/Equinox.Core/Batching.fs

@@ -18,16 +18,16 @@ type internal AsyncBatch<'Req, 'Res>() =
             // sadly there's no way to detect without a try/catch
             try queue.TryAdd(item)
             with :? InvalidOperationException -> false
-    let mutable attempt = Unchecked.defaultof<Lazy<Task<'Res[]>>>
+    let mutable attempt = Unchecked.defaultof<Lazy<Task<'Res>>>
 
     /// Attempt to add a request to the flight
     /// Succeeds during linger interval (which commences when the first caller triggers the workflow via AwaitResult)
     /// Fails if this flight has closed (caller should initialize a fresh Batch, potentially holding off until the current attempt completes)
-    member _.TryAdd(req, dispatch: Func<'Req[], CancellationToken, Task<'Res[]>>, lingerMs: int, limiter: System.Threading.SemaphoreSlim voption, ct) =
+    member _.TryAdd(req, dispatch: Func<'Req[], CancellationToken, Task<'Res>>, lingerMs: int, limiter: System.Threading.SemaphoreSlim voption, ct) =
         if not (tryEnqueue req) then false else
 
-        // Prepare a new instance, with cancellation under our control (it won't start until the Force triggers it though)
-        let newInstance: Lazy<Task<'Res[]>> = lazy task {
+        // Prepare a new instance, with cancellation under our control (it won't start until the .Value triggers it though)
+        let newInstance: Lazy<Task<'Res>> = lazy task {
             do! Task.Delay(lingerMs, ct)
             match limiter with ValueNone -> () | ValueSome s -> do! s.WaitAsync(ct)
             try queue.CompleteAdding()
@@ -45,12 +45,12 @@ type internal AsyncBatch<'Req, 'Res>() =
 /// Requests are added to pending batch during the wait period, which consists of two phases:
 /// 1. a defined linger period (min 1ms)
 /// 2. (optionally) a wait to acquire capacity on a limiter semaphore (e.g. one might have a limit on concurrent dispatches across a pool)
-type Batcher<'Req, 'Res> private (tryInclude: Func<AsyncBatch<_, _>, 'Req, CancellationToken, bool>) =
+type Batcher<'Req, 'Res> private (tryInclude: Func<AsyncBatch<'Req, 'Res>, 'Req, CancellationToken, bool>) =
     let mutable cell = AsyncBatch<'Req, 'Res>()
-    new(dispatch: Func<'Req[], CancellationToken, Task<'Res[]>>, lingerMs, limiter) =
+    new(dispatch: Func<'Req[], CancellationToken, Task<'Res>>, lingerMs, limiter) =
         if lingerMs < 1 then invalidArg (nameof(lingerMs)) "Minimum linger period is 1ms" // concurrent waiters need to add work to the batch across their threads
         Batcher(fun cell req ct -> cell.TryAdd(req, dispatch, lingerMs, limiter, ct = ct))
-    new(dispatch: 'Req[] -> Async<'Res[]>, ?linger : TimeSpan,
+    new(dispatch: 'Req[] -> Async<'Res>, ?linger: TimeSpan,
         // Extends the linger phase to include a period during which we await capacity on an externally managed Semaphore
         // The Batcher doesn't care, but a typical use is to enable limiting the number of concurrent in-flight dispatches
         ?limiter) =