List.mapi2<'T1,'T2,'U> Function (F#)
Like List.mapi, but mapping corresponding elements from two lists of equal length.
Namespace/Module Path: Microsoft.FSharp.Collections.List
Assembly: FSharp.Core (in FSharp.Core.dll)
// Signature:
List.mapi2 : (int -> 'T1 -> 'T2 -> 'U) -> 'T1 list -> 'T2 list -> 'U list
// Usage:
List.mapi2 mapping list1 list2
Parameters
mapping
Type: int -> 'T1 -> 'T2 -> 'UThe function to transform pairs of elements from the two lists and their index.
list1
Type: 'T1listThe first input list.
list2
Type: 'T2listThe second input list.
Return Value
The list of transformed elements.
Remarks
This function is named MapIndexed2 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 example illustrates the use of List.mapi2.
let list1 = [1; 2; 3]
let list2 = [4; 5; 6]
let listAddTimesIndex = List.mapi2 (fun i x y -> (x + y) * i) list1 list2
printfn "%A" listAddTimesIndex
Output
[0; 7; 18]
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