make AsyncSeq.mapi public

Author: enricosada

src/FSharp.Control.AsyncSeq/AsyncSeq.fsi

@@ -321,6 +321,13 @@ module AsyncSeq =
     /// be asked for the next element after the processing of an element completes).
     val mapiAsync : mapping:(int64 -> 'T -> Async<'U>) -> source:AsyncSeq<'T> -> AsyncSeq<'U>
 
+    /// Builds a new asynchronous sequence whose elements are generated by 
+    /// applying the specified function to all elements of the input sequence.
+    ///
+    /// The specified function is synchronous (and the input sequence will
+    /// be asked for the next element after the processing of an element completes).
+    val mapi : mapping:(int64 -> 'T -> 'U) -> source:AsyncSeq<'T> -> AsyncSeq<'U>
+
     [<System.Obsolete("Renamed to mapiAsync") >]
     val zipWithIndexAsync : mapping:(int64 -> 'T -> Async<'U>) -> source:AsyncSeq<'T> -> AsyncSeq<'U>
 

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

@@ -1378,6 +1378,20 @@ let ``AsyncSeq.unfoldAsync should be iterable in finite resources``() =
 
 
 
+[<Test>]
+let ``AsyncSeq.mapi should work`` () =
+  for i in 0..100 do
+    let ls = List.init i (fun x -> x + 100)
+    let expected =
+      ls
+      |> List.mapi (fun i x -> sprintf "%i_%i" i x)
+    let actual = 
+      ls 
+      |> AsyncSeq.ofSeq 
+      |> AsyncSeq.mapi (fun i x -> sprintf "%i_%i" i x)
+      |> AsyncSeq.toList
+    Assert.AreEqual(expected, actual)
+
 
 [<Test>]
 let ``AsyncSeq.take should work``() =