Map.pick<'Key,'T,'U> Function (F#)

项目
04/28/2015

Searches the map looking for the first element where the given function returns a Some value

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

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

// Signature:
Map.pick : ('Key -> 'T -> 'U option) -> Map<'Key,'T> -> 'U (requires comparison)

// Usage:
Map.pick chooser table

Parameters

chooser
Type: 'Key -> 'T -> 'Uoption

The function to generate options from the key/value pairs.
table
Type: Map<'Key,'T>

The input map.

Return Value

The first result.

Remarks

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

Example

The following code shows how to use Map.pick.

let map1 = [ for i in 1 .. 100 -> (i, 100 - i) ] |> Map.ofList
let result = Map.pick (fun key value -> if key = value then Some(key) else None) map1
printfn "Result where key and value are the same: %d" result

Output

Result where key and value are the same: 50

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

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