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AsyncBuilder.While Method (F#)

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

Implements the while keyword in asynchronous computation expressions.

Namespace/Module Path: Microsoft.FSharp.Control

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


// Signature:
member this.While : (unit -> bool) * Async<unit> -> Async<unit>

// Usage:
asyncBuilder.While (guard, computation)


guard Type: unit->bool

The function to determine when to stop executing computation.

computation Type: Async<unit>

The function to be executed. Equivalent to the body of a while expression.

Return Value

An asynchronous computation that behaves similarly to a while loop when run.


Creates an asynchronous computation that runs computation repeatedly until guard evaluates to false.

A cancellation check is performed whenever the computation is executed. The existence of this method permits the use of while in the async { ... } computation expression syntax.


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.AsyncBuilder Class (F#)

Microsoft.FSharp.Control Namespace (F#)

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