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

  • Article

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

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

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

// Signature:
Seq.forall : ('T -> bool) -> seq<'T> -> bool

// Usage:
Seq.forall predicate source

Parameters

  • predicate
    Type: 'T -> bool

    A function to test an element of the input sequence.

  • source
    Type: seq<'T>

    The input sequence.

Exceptions

Exception

Condition

ArgumentNullException

Thrown when the input sequence is null.

Return Value

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

Remarks

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

Example

The following code shows how to use Seq.forall.

// This function can be used on any sequence, so the same function
// works with both lists and arrays.
let allPositive = Seq.forall (fun elem -> elem > 0)
printfn "%A" (allPositive [| 0; 1; 2; 3 |])
printfn "%A" (allPositive [ 1; 2; 3 ])

Output

false
true

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.Seq Module (F#)

Microsoft.FSharp.Collections Namespace (F#)