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Array.choose<'T,'U> Function (F#)

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

Applies the given function to each element of the array. Returns the array comprised of the results x for each element where the function returns Some(x).

Namespace/Module Path: Microsoft.FSharp.Collections.Array

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


// Signature:
Array.choose : ('T -> 'U option) -> 'T [] -> 'U []

// Usage:
Array.choose chooser array


chooser Type: 'T -> 'Uoption

The function to generate options from the elements.

array Type: 'T[]

The input array.

Return Value

The array of results.


This function is named Choose in compiled assemblies. If you are accessing the function from a language other than F#, or through reflection, use this name.


The following code demonstrates the use of Array.choose to perform an operation only on the even numbers in an array.

printfn "%A" (Array.choose (fun elem -> if elem % 2 = 0 then
                                            Some(float (elem*elem - 1))
                                            None) [| 1 .. 10 |])
[|3.0; 15.0; 35.0; 63.0; 99.0|]


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

Collections.Array Module (F#)

Microsoft.FSharp.Collections Namespace (F#)

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