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Async.FromBeginEnd<'Arg1,'Arg2,'T> Method (F#)

Den Delimarsky|Last Updated: 8/18/2017
1 Contributor

Creates an asynchronous computation in terms of a Begin/End pair of actions in the style used in CLI APIs.

Namespace/Module Path: Microsoft.FSharp.Control

Assembly: FSharp.Core (in FSharp.Core.dll)


// Signature:
static member FromBeginEnd : 'Arg1 * 'Arg2 * ('Arg1 * 'Arg2 * AsyncCallback * obj -> IAsyncResult) * (IAsyncResult -> 'T) * ?(unit -> unit) -> Async<'T>

// Usage:
Async.FromBeginEnd (arg1, arg2, beginAction, endAction)
Async.FromBeginEnd (arg1, arg2, beginAction, endAction, cancelAction = cancelAction)


arg1 Type: 'Arg1

The first argument for the operation.

arg2 Type: 'Arg2

The second argument for the operation.

beginAction Type: 'Arg1 * 'Arg2 * System.AsyncCallback * obj -> System.IAsyncResult

The function initiating a traditional CLI asynchronous operation.

endAction Type: System.IAsyncResult -> 'T

The function completing a traditional CLI asynchronous operation.

cancelAction Type: unit -> unit

An optional function to be executed when a cancellation is requested.

Return Value

Returns an asynchronous computation wrapping the given Begin/End functions.


This overload should be used if the operation is qualified by two arguments. For example, the following code creates an asynchronous computation for a web service call.


When the computation is run, beginFunc is executed, with a callback which represents the continuation of the computation. When the callback is invoked, the overall result is fetched using endFunc.

The computation will respond to cancellation while waiting for the completion of the operation. If a cancellation occurs, and cancelAction is specified, then it is executed, and the computation continues to wait for the completion of the operation. If cancelAction is not specified, then cancellation causes the computation to stop immediately, and subsequent invocations of the callback are ignored.

For an example, see Async.FromBeginEnd<'T> Method (F#).


Windows 8, Windows 7, Windows Server 2012, Windows Server 2008 R2

Version Information

F# Core Library Versions

Supported in: 2.0, 4.0, Portable

See Also

Control.Async Class (F#)

Microsoft.FSharp.Control Namespace (F#)

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