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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


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

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


Type: 'T list

The input list.




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

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



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

F# Core Library Versions

Supported in: 2.0, 4.0, Portable

© 2015 Microsoft