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

  • Article

Tests if all elements of the collection satisfy the given predicate.

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

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

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

// Usage:
List.forall predicate list

Parameters

  • predicate
    Type: 'T ->bool

    The function to test the input elements.

  • list
    Type: 'Tlist

    The input list.

Return Value

true if all of the elements satisfy the predicate. Otherwise, returns false.

Remarks

The predicate is applied to the elements of the input list. If any application returns false then the overall result is false and no further elements are tested. Otherwise, true is returned.

This function is named ForAll 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 illustrates the use of List.forall.

let isAllZeroes list = List.forall (fun elem -> elem = 0.0) list
printfn "%b" (isAllZeroes [0.0; 0.0])
printfn "%b" (isAllZeroes [0.0; 1.0])

Output

true
false

Platforms

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

Reference

Collections.List Module (F#)

Microsoft.FSharp.Collections Namespace (F#)