List.collect<'T,'U> Function (F#)

For each element of the list, applies the given function. Concatenates all the results and returns the combined list.

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

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

// Signature:
List.collect : ('T -> 'U list) -> 'T list -> 'U list

// Usage:
List.collect mapping list


  • mapping
    Type: 'T -> 'U list

    The function to transform each input element into a sublist to be concatenated.

  • list
    Type: 'T list

    The input list.

Return Value

The concatenation of the resulting sublists.


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


The following code example illustrates the use of List.collect.

let list1 = [10; 20; 30]
let collectList = List.collect (fun x -> [for i in 1..3 -> x * i]) list1
printfn "%A" collectList


[1; 2; 3; 2; 4; 6; 3; 6; 9]


Windows 7, Windows Vista SP2, Windows XP SP3, Windows XP x64 SP2, Windows Server 2008 R2, Windows Server 2008 SP2, Windows Server 2003 SP2

Version Information

F# Runtime

Supported in: 2.0, 4.0


Supported in: 3

See Also


Collections.List Module (F#)

Microsoft.FSharp.Collections Namespace (F#)