List.tryFind<'T> Function (F#)
Returns the first element for which the given function returns true
. Returns None
if no such element exists.
Namespace/Module Path: Microsoft.FSharp.Collections.List
Assembly: FSharp.Core (in FSharp.Core.dll)
Syntax
// Signature:
List.tryFind : ('T -> bool) -> 'T list -> 'T option
// Usage:
List.tryFind predicate list
Parameters
predicate Type: 'T ->bool
The function to test the input elements.
list Type: 'Tlist
The input list.
Return Value
The first element for which the predicate returns true
, or None if every element evaluates to false
.
Remarks
This function is named TryFind
in compiled assemblies. If you are accessing the function from a language other than F#, or through reflection, use this name.
Example
let list1d = [1; 3; 7; 9; 11; 13; 15; 19; 22; 29; 36]
let isEven x = x % 2 = 0
match List.tryFind isEven list1d with
| Some value -> printfn "The first even value is %d." value
| None -> printfn "There is no even value in the list."
match List.tryFindIndex isEven list1d with
| Some value -> printfn "The first even value is at position %d." value
| None -> printfn "There is no even value in the list."
Output
The first even value is 22.
The first even value is at position 8.
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