Add YieldFrom overload for seq<'T> in asyncSeq computation expression

src/FSharp.Control.AsyncSeq/AsyncSeq.fs

@@ -868,6 +868,9 @@
     member x.For (seq:AsyncSeq<'T>, action:'T -> AsyncSeq<'TResult>) =
       collect action seq
 
+    member x.YieldFrom (s:seq<'T>) =
+      ofSeq s
+
   let unfoldAsync (f:'State -> Async<('T * 'State) option>) (s:'State) : AsyncSeq<'T> =
     new UnfoldAsyncEnumerator<_, _>(f, s) :> _
 
@@ -2017,7 +2020,7 @@
 
   [<CompilerMessage("The result of groupBy must be consumed with a parallel combinator such as AsyncSeq.mapAsyncParallel. Sequential consumption will deadlock because sub-sequence completion depends on other sub-sequences being consumed concurrently.", 9999)>]
   let groupBy (p:'a -> 'k) (s:AsyncSeq<'a>) : AsyncSeq<'k * AsyncSeq<'a>> =
     groupByAsync (p >> async.Return) s
   #endif
   #endif
 

src/FSharp.Control.AsyncSeq/AsyncSeq.fsi

@@ -112,6 +112,9 @@ module AsyncSeq =
         /// Implements "yield!" for the asyncSeq computation builder.
         member YieldFrom : source:AsyncSeq<'T> -> AsyncSeq<'T>
 
+        /// Implements "yield!" for a synchronous sequence in the asyncSeq computation builder.
+        member YieldFrom : source:seq<'T> -> AsyncSeq<'T>
+
         /// Implements empty for the asyncSeq computation builder.
         member Zero : unit -> AsyncSeq<'T>
 

tests/FSharp.Control.AsyncSeq.Tests/AsyncSeqTests.fs

@@ -156,6 +156,26 @@
   Assert.True(([1;2;3] = a))
 
 
+[<Test>]
+let ``asyncSeq yield! seq works``() =
+  let items = seq { 1; 2; 3 }
+  let s = asyncSeq {
+    yield! items
+  }
+  let a = s |> AsyncSeq.toListSynchronously
+  Assert.True(([1;2;3] = a))
+
+[<Test>]
+let ``asyncSeq yield! seq combines with other yields``() =
+  let items = seq { 2; 3 }
+  let s = asyncSeq {
+    yield 1
+    yield! items
+    yield 4
+  }
+  let a = s |> AsyncSeq.toListSynchronously
+  Assert.True(([1;2;3;4] = a))
+
 [<Test>]
 let ``AsyncSeq.concatSeq works``() =
   let ls = [ [1;2] ; [3;4] ]
@@ -1830,7 +1850,7 @@
       let actual =
         ls
         |> AsyncSeq.ofSeq
         |> AsyncSeq.groupBy p
         |> AsyncSeq.mapAsyncParallel (snd >> AsyncSeq.toListAsync)
       Assert.AreEqual(expected, actual)
 
@@ -1839,7 +1859,7 @@
   let expected = asyncSeq { raise (exn("test")) }
   let actual =
     asyncSeq { raise (exn("test")) }
     |> AsyncSeq.groupBy (fun i -> i % 3)
     |> AsyncSeq.mapAsyncParallel (snd >> AsyncSeq.toListAsync)
   Assert.AreEqual(expected, actual)