Map.tryFindKey<'Key,'T> Function (F#)
Returns the key of the first mapping in the collection that satisfies the given predicate, or returns None if no such element exists.
Namespace/Module Path: Microsoft.FSharp.Collections.Map
Assembly: FSharp.Core (in FSharp.Core.dll)
// Signature:
Map.tryFindKey : ('Key -> 'T -> bool) -> Map<'Key,'T> -> 'Key option (requires comparison)
// Usage:
Map.tryFindKey predicate table
Parameters
predicate
Type: 'Key -> 'T ->boolThe function to test the input elements.
table
Type: Map<'Key,'T>The input map.
Return Value
The first key for which the predicate returns true or None if the predicate evaluates to false for each key/value pair.
Remarks
This function is named TryFindKey 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 shows the use of the Map.tryFindKey function.
let map1 = [ for i in 1 .. 100 -> (i, i*i) ] |> Map.ofList
let result = Map.tryFindKey (fun key value -> key = value) map1
match result with
| Some key -> printfn "Found element with key %d." key
| None -> printfn "Did not find any element that matches the condition."
Output
Found element with key 1.
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