List.partition<'T> Function (F#)

Splits the collection into two collections, containing the elements for which the given predicate returns true and false respectively.

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

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

// Signature:
List.partition : ('T -> bool) -> 'T list -> 'T list * 'T list

// Usage:
List.partition predicate list

Parameters

• predicate
  Type: 'T -> bool

  The function to test the input elements.

• list
  Type: 'T list

  The input list.

Return Value

A list containing the elements for which the predicate evaluated to false and a list containing the elements for which the predicate evaluated to true.

Remarks

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

Example

The following code example shows how to use List.partition.

let list1 = [ 1 .. 10 ]
let listEven, listOdd = List.partition (fun elem -> elem % 2 = 0) list1
printfn "Evens: %A\nOdds: %A" listEven listOdd

Output

Evens: [2; 4; 6; 8; 10]
Odds: [1; 3; 5; 7; 9]

Platforms

Windows 7, Windows Vista SP2, Windows XP SP3, Windows XP x64 SP2, Windows Server 2008 R2, Windows Server 2008 SP2, Windows Server 2003 SP2

Version Information

F# Runtime

Supported in: 2.0, 4.0

Silverlight

Supported in: 3

See Also

Reference

Collections.List Module (F#)

Microsoft.FSharp.Collections Namespace (F#)