integrate master

Author: dsyme

README.md

@@ -1,7 +1,7 @@
 [![Issue Stats](http://issuestats.com/github/fsprojects/FSharp.Control.AsyncSeq/badge/issue)](http://issuestats.com/github/fsprojects/FSharp.Control.AsyncSeq)
 [![Issue Stats](http://issuestats.com/github/fsprojects/FSharp.Control.AsyncSeq/badge/pr)](http://issuestats.com/github/fsprojects/FSharp.Control.AsyncSeq)
-[![Build status](https://ci.appveyor.com/api/projects/status/k7lyn5rqeuqagyi2/branch/master?svg=true)](https://ci.appveyor.com/project/SteffenForkmann/asyncseq/branch/master)
-[![Build status](https://travis-ci.org/fsprojects/FSharp.Control.AsyncSeq.svg?branch=master)](https://travis-ci.org/fsprojects/AsyncSeq)
+[![Build status](https://ci.appveyor.com/api/projects/status/22wknie0x5c2jfuo/branch/master?svg=true)](https://ci.appveyor.com/project/SteffenForkmann/fsharp-control-asyncseq/branch/master)
+[![Build status](https://travis-ci.org/fsprojects/FSharp.Control.AsyncSeq.svg?branch=master)](https://travis-ci.org/fsprojects/FSharp.Control.AsyncSeq)
 
 # FSharp.Control.AsyncSeq [![NuGet Status](http://img.shields.io/nuget/v/FSharp.Control.AsyncSeq.svg?style=flat)](https://www.nuget.org/packages/FSharp.Control.AsyncSeq/)
 

src/FSharp.Control.AsyncSeq/AsyncSeq.fs

@@ -136,7 +136,7 @@ module AsyncSeq =
     //     do! something
     //
     // because F# translates body as Bind(something, fun () -> Return())
-    member x.Return() = empty
+    member x.Return _ = empty
     member x.YieldFrom(s) = s
     member x.Zero () = empty
     member x.Bind (inp:Async<'T>, body : 'T -> AsyncSeq<'U>) : AsyncSeq<'U> = 
@@ -255,14 +255,16 @@ module AsyncSeq =
     | Nil -> return def
     | Cons(h, _) -> return h }
 
-  let rec scanAsync f (state:'State) (input : AsyncSeq<'T>) = asyncSeq {
-    let! v = input
-    match v with
-    | Nil -> ()
-    | Cons(h, t) ->
+  let scanAsync f (state:'TState) (input : AsyncSeq<'T>) =    
+    let rec go f state s = asyncSeq {
+      let! v = s
+      match v with
+      | Nil -> ()
+      | Cons(h, t) ->
         let! v = f state h
         yield v
-        yield! t |> scanAsync f v }
+        yield! t |> go f v }
+    asyncSeq { yield state ; yield! go f state input }
 
   let iterAsync f (input : AsyncSeq<'T>) = async {
     for itm in input do 

src/FSharp.Control.AsyncSeq/AsyncSeq.fsi

@@ -59,7 +59,7 @@ module AsyncSeq =
         member For : seq:AsyncSeq<'T> * action:('T -> AsyncSeq<'TResult>) -> AsyncSeq<'TResult>
 
         /// Implements "return" for the asyncSeq computation builder.
-        member Return : unit -> AsyncSeq<'T>
+        member Return : 'unit -> AsyncSeq<'T> 
 
         /// Implements "try-finally" for the asyncSeq computation builder.
         member TryFinally : body:AsyncSeq<'T> * compensation:(unit -> unit) -> AsyncSeq<'T>

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

@@ -153,7 +153,16 @@ let ``AsyncSeq.scanAsync``() =
   let f i a = i + a
   let z = 0
   let actual = ls |> AsyncSeq.ofSeq |> AsyncSeq.scanAsync (fun i a -> f i a |> async.Return) z
-  let expected = ls |> Seq.scan f z |> Seq.skip 1 |> AsyncSeq.ofSeq
+  let expected = ls |> List.scan f z |> AsyncSeq.ofSeq
+  Assert.True(EQ expected actual)
+
+[<Test>]
+let ``AsyncSeq.scanAsync on empty should emit initial state``() =
+  let ls = List.empty
+  let f i a = i + a
+  let z = 0
+  let actual = ls |> AsyncSeq.ofSeq |> AsyncSeq.scanAsync (fun i a -> f i a |> async.Return) z
+  let expected = ls |> List.scan f z |> AsyncSeq.ofSeq
   Assert.True(EQ expected actual)
 
 
@@ -291,7 +300,6 @@ let ``AsyncSeq.skipUntil should skip everything with never signal``() =
   let actual = [1;2;3;4] |> AsyncSeq.ofSeq |> AsyncSeq.skipUntil AsyncOps.never
   Assert.True(EQ AsyncSeq.empty actual)
 
-
 [<Test>]
 let ``AsyncSeq.toBlockingSeq should work length 1``() =
   let s = asyncSeq { yield 1 } |> AsyncSeq.toBlockingSeq  |> Seq.toList
@@ -349,3 +357,11 @@ let ``AsyncSeq.toBlockingSeq should be cancellable``() =
   System.Threading.Thread.Sleep(1000) // wait for task cancellation to be effective
   Assert.AreEqual(cancelCount.Value, 1)
 
+[<Test>]
+let ``AsyncSeq.while should allow do at end``() =  
+  let s1 = asyncSeq {
+    while false do 
+        yield 1
+        do! Async.Sleep 10
+  }
+  Assert.True(true)