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

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


  • predicate
    Type: 'T -> bool

    The function to test the input elements.

  • list
    Type: 'T list

    The input list.

Return Value

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


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.


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])




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


Supported in: 3

See Also


Collections.List Module (F#)

Microsoft.FSharp.Collections Namespace (F#)