+ (Value)Task.mapError

Author: gusty

src/FSharpPlus/Extensions/Task.fs

@@ -487,7 +487,7 @@ module Task =
     let inline recover ([<InlineIfLambda>]mapper: exn -> 'T) (source: Task<'T>) : Task<'T> =
         let source = nullArgCheck (nameof source) source
 
-        tryWith (fun () -> source) (mapper >> Task.FromResult)
+        tryWith (fun () -> source) (mapper >> Task.FromResult)    
     #else
     let inline recover (mapper: exn -> 'T) (source: Task<'T>) : Task<'T> =
         raiseIfNull "source" source
@@ -499,7 +499,17 @@ module Task =
     /// <param name="mapper">Mapping function from exception to exception.</param>
     /// <param name="source">The source task.</param>
     /// <returns>The resulting task.</returns>
+    #if !NET45
+    let inline mapError ([<InlineIfLambda>]mapper: exn -> exn) (source: Task<'T>) : Task<'T> =
+    #else
     let mapError (mapper: exn -> exn) (source: Task<'T>) : Task<'T> =
+    #endif
+        #if NET5_0_OR_GREATER
+        let tcsOptions' = TaskCreationOptions.RunContinuationsAsynchronously
+        #else
+        let tcsOptions' = ()
+        #endif
+
         #if !NET45
         let source = nullArgCheck (nameof source) source
         #else
@@ -511,7 +521,7 @@ module Task =
             | Faulted exn -> FromExceptions (AggregateException (mapper exn))
             | _           -> source
         else
-            let tcs = TaskCompletionSource<'T> tcsOptions
+            let tcs = TaskCompletionSource<'T> tcsOptions'
             let k = function
                 | Succeeded r -> tcs.SetResult r
                 | Faulted aex -> tcs.SetException (AggregateException (mapper aex)).InnerExceptions

src/FSharpPlus/Extensions/ValueTask.fs

@@ -407,7 +407,13 @@ module ValueTask =
             | Faulted exn -> FromExceptions (AggregateException (mapper exn))
             | _           -> source
         else
-            let tcs = TaskCompletionSource<'T> tcsOptions
+            #if NET5_0_OR_GREATER
+            let tcsOptions' = TaskCreationOptions.RunContinuationsAsynchronously
+            #else
+            let tcsOptions' = ()
+            #endif
+
+            let tcs = TaskCompletionSource<'T> tcsOptions'
             let k = function
                 | Succeeded r -> tcs.SetResult r
                 | Faulted aex -> tcs.SetException (AggregateException (mapper aex)).InnerExceptions