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F# Core Library Reference

Microsoft.FSharp.Collections Namespace (F#)

Collections.List Module (F#)

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

List.average<^T> Function (F#)

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

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

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

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

List.empty<'T> Type Function (F#)

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

List.exists2<'T1,'T2> Function (F#)

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

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

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

List.fold<'T,'State> Function (F#)

List.fold2<'T1,'T2,'State> Function (F#)

List.foldBack<'T,'State> Function (F#)

List.foldBack2<'T1,'T2,'State> Function (F#)

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

List.forall2<'T1,'T2> Function (F#)

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

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

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

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

List.iter2<'T1,'T2> Function (F#)

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

List.iteri2<'T1,'T2> Function (F#)

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

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

List.map2<'T1,'T2,'U> Function (F#)

List.map3<'T1,'T2,'T3,'U> Function (F#)

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

List.mapi2<'T1,'T2,'U> Function (F#)

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

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

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

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

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

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

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

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

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

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

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

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

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

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

List.scan<'T,'State> Function (F#)

List.scanBack<'T,'State> Function (F#)

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

List.sortBy<'T,'Key> Function (F#)

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

List.sum<^T> Function (F#)

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

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

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

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

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

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

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

List.unzip<'T1,'T2> Function (F#)

List.unzip3<'T1,'T2,'T3> Function (F#)

List.zip<'T1,'T2> Function (F#)

List.zip3<'T1,'T2,'T3> Function (F#)

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

Visual Studio 2010

Visual Studio 2012

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

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

Silverlight

Supported in: 3

Reference

Collections.List Module (F#)

Microsoft.FSharp.Collections Namespace (F#)

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