Async.map, bind, unit

Author: eulerfx

src/FSharpx.Async/Async.fs

@@ -8,10 +8,14 @@ open System.Threading
 
 // ----------------------------------------------------------------------------
 
-[<AutoOpen>]
-module AsyncExtensions = 
-    type Microsoft.FSharp.Control.Async with 
+module AsyncOps =
+      
+  let unit : Async<unit> = async.Return()
+ 
 
+[<AutoOpen>]
+module AsyncExtensions =             
+    type Microsoft.FSharp.Control.Async with       
       /// Creates an asynchronous workflow that runs the asynchronous workflow
       /// given as an argument at most once. When the returned workflow is 
       /// started for the second time, it reuses the result of the 
@@ -34,4 +38,16 @@ module AsyncExtensions =
           let ct = new System.Threading.CancellationTokenSource()
           Async.Start(op, ct.Token)
           { new IDisposable with 
-              member x.Dispose() = ct.Cancel() }
+              member x.Dispose() = ct.Cancel() }
+
+      /// An async computation which does nothing.
+      static member inline unit = AsyncOps.unit
+
+      /// Creates an async computation which maps a function f over the 
+      /// value produced by the specified asynchronous computation.
+      static member inline map f a = async.Bind(a, f >> async.Return)
+
+      /// Creates an async computation which binds the result of the specified 
+      /// async computation to the specified function. The computation produced 
+      /// by the specified function is returned.
+      static member inline bind f a = async.Bind(a, f)