Export (0) Print
Expand All
Expand Minimize

List.reduce<'T> Function (F#)

Applies a function to each element of the collection, threading an accumulator argument through the computation. This function first applies the function to the first two elements of the list. Then, it passes this result into the function along with the third element and so on. Finally, it returns the final result. If the input function is f and the elements are i0...iN, then it computes f (... (f i0 i1) i2 ...) iN.

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

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

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

// Usage:
List.reduce reduction list

reduction

Type: 'T -> 'T -> 'T

The function to reduce two list elements to a single element.

list

Type: 'T list

The input list.

Exception

Condition

ArgumentException

Thrown when the list is empty.

The final reduced value.

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

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

let sumAList list =
    try
        List.reduce (fun acc elem -> acc + elem) list
    with
       | :? System.ArgumentException as exc -> 0

let resultSum = sumAList [2; 4; 10]
printfn "%d " resultSum

Output

16

Windows 8, Windows 7, Windows Server 2012, Windows Server 2008 R2

F# Core Library Versions

Supported in: 2.0, 4.0, Portable

Show:
© 2014 Microsoft