Map.filter<'Key,'T> Function (F#)
Creates a new map containing only the bindings for which the given predicate returns true.
Namespace/Module Path: Microsoft.FSharp.Collections.Map
Assembly: FSharp.Core (in FSharp.Core.dll)
// Signature:
Map.filter : ('Key -> 'T -> bool) -> Map<'Key,'T> -> Map<'Key,'T> (requires comparison)
// Usage:
Map.filter predicate table
Parameters
predicate
Type: 'Key -> 'T ->boolThe function to test the key/value pairs.
table
Type: Map<'Key,'T>The input map.
Return Value
The filtered map.
Remarks
This function is named Filter 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 how to use Map.filter.
printfn "Even numbers and their squares."
let map1 = Map.ofList [for i in 1 .. 10 -> (i, i*i)]
|> Map.filter (fun key _ -> key % 2 = 0)
|> Map.iter (fun key value -> printf "(%d, %d) " key value)
printfn ""
Output
Even numbers and their squares. (2, 4) (4, 16) (6, 36) (8, 64) (10, 100)
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