List.exists2<'T1,'T2> Function (F#)
Tests if any pair of corresponding elements of the lists satisfies the given predicate.
Namespace/Module Path: Microsoft.FSharp.Collections.List
Assembly: FSharp.Core (in FSharp.Core.dll)
// Signature:
List.exists2 : ('T1 -> 'T2 -> bool) -> 'T1 list -> 'T2 list -> bool
// Usage:
List.exists2 predicate list1 list2
Parameters
predicate
Type: 'T1 -> 'T2 ->boolThe function to test the input elements.
list1
Type: 'T1listThe first input list.
list2
Type: 'T2listThe second input list.
Return Value
true if any pair of elements satisfy the predicate. Otherwise, returns false.
Remarks
The predicate is applied to matching elements in the two collections up to the lesser of the two lengths of the collections. If any application returns true then the overall result is true and no further elements are tested.
This function is named Exists2 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 example illustrates the use of List.exists2.
// Use List.exists2 to compare elements in two lists.
// isEqualElement returns true if any elements at the same position in two supplied
// lists match.
let isEqualElement list1 list2 = List.exists2 (fun elem1 elem2 -> elem1 = elem2) list1 list2
let list1to5 = [ 1 .. 5 ]
let list5to1 = [ 5 .. -1 .. 1 ]
if (isEqualElement list1to5 list5to1) then
printfn "Lists %A and %A have at least one equal element at the same position." list1to5 list5to1
else
printfn "Lists %A and %A do not have an equal element at the same position." list1to5 list5to1
Output
Lists [1; 2; 3; 4; 5] and [5; 4; 3; 2; 1] have at least one equal element at the same position.
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