Add getIterator

Author: dsyme

RELEASE_NOTES.md

@@ -1,3 +1,11 @@
+### 1.15.0 - 30.03.2015
+* Add AsyncSeq.getIterator (unblocks use of AsyncSeq in FSharpx.Async)
+
+### 1.14 - 30.03.2015
+* Cancellable AsyncSeq.toBlockingSeq
+* Fix AsyncSeq.scanAsync to also return first state
+* Add a signature file
+
 ### 1.13 - 27.03.2015
 * Renamed to FSharp.Control.AsyncSeq
 * Remove surface area

src/FSharp.Control.AsyncSeq/AssemblyInfo.fs

@@ -4,9 +4,9 @@ open System.Reflection
 [<assembly: AssemblyTitleAttribute("FSharp.Control.AsyncSeq")>]
 [<assembly: AssemblyProductAttribute("FSharp.Control.AsyncSeq")>]
 [<assembly: AssemblyDescriptionAttribute("Asynchronous sequences for F#")>]
-[<assembly: AssemblyVersionAttribute("1.13")>]
-[<assembly: AssemblyFileVersionAttribute("1.13")>]
+[<assembly: AssemblyVersionAttribute("1.15.0")>]
+[<assembly: AssemblyFileVersionAttribute("1.15.0")>]
 do ()
 
 module internal AssemblyVersionInformation =
-    let [<Literal>] Version = "1.13"
+    let [<Literal>] Version = "1.15.0"

src/FSharp.Control.AsyncSeq/AsyncSeq.fs

@@ -286,7 +286,7 @@ module AsyncSeq =
   let fold f (state:'State) (input : AsyncSeq<'T>) = 
     foldAsync (fun st v -> f st v |> async.Return) state input 
 
-  let rec scan f (state:'State) (input : AsyncSeq<'T>) = 
+  let scan f (state:'State) (input : AsyncSeq<'T>) = 
     scanAsync (fun st v -> f st v |> async.Return) state input 
 
   let map f (input : AsyncSeq<'T>) = 
@@ -649,7 +649,14 @@ module AsyncSeq =
 
   let distinctUntilChanged (s:AsyncSeq<'T>) : AsyncSeq<'T> =
     distinctUntilChangedWith ((=)) s
-        
+
+  let getIterator (s:AsyncSeq<'T>) = 
+      let curr = ref s
+      fun () -> 
+          async { let! v = curr.Value 
+                  match v with 
+                  | Nil -> return None
+                  | Cons (v,t) -> curr := t; return Some v } 
 
 
 

src/FSharp.Control.AsyncSeq/AsyncSeq.fsi

@@ -303,7 +303,8 @@ module AsyncSeq =
     /// Returns an async sequence which contains no contiguous duplicate elements.
     val distinctUntilChanged : s:AsyncSeq<'T> -> AsyncSeq<'T> when 'T : equality
 
-
+    /// Get a function that may be usesd as an async iterator for the sequence. This functionality may be replaced in later versions of this library.
+    val getIterator : s:AsyncSeq<'T> -> (unit -> Async<'T option>)
 
 /// An automatically-opened module tht contains the `asyncSeq` builder and an extension method 
 [<AutoOpen>]

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

@@ -365,3 +365,21 @@ let ``AsyncSeq.while should allow do at end``() =
         do! Async.Sleep 10
   }
   Assert.True(true)
+
+[<Test>]
+let ``AsyncSeq.getIterator should work``() =  
+  let s1 = [1..2] |> AsyncSeq.ofSeq
+  let i = AsyncSeq.getIterator s1
+  match i() |> Async.RunSynchronously with 
+  | None -> Assert.Fail("expected Some")
+  | Some v -> 
+    Assert.AreEqual(v,1)
+    match i() |> Async.RunSynchronously with 
+    | None -> Assert.Fail("expected Some")
+    | Some v -> 
+        Assert.AreEqual(v,2)
+        match i() |> Async.RunSynchronously with 
+        | None -> ()
+        | Some _ -> Assert.Fail("expected None")
+
+