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

Den Delimarsky|Last Updated: 8/18/2017
1 Contributor

Attempts to find the first element that satisfies a given predicate, and returns the index of the matching element.

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

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


// Signature:
Seq.tryFindIndex : ('T -> bool) -> seq<'T> -> int option

// Usage:
Seq.tryFindIndex predicate source


predicate Type: 'T ->bool

A function that evaluates to a Boolean when given an item in the sequence.

source Type: seq<'T>

The input sequence.


ArgumentNullExceptionThrown when the input sequence is null.

Return Value

Returns the index of the first element in the sequence that satisfies the given predicate, or None if no such element exists.


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


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

Version Information

F# Core Library Versions

Supported in: 2.0, 4.0, Portable

See Also

Collections.Seq Module (F#)

Microsoft.FSharp.Collections Namespace (F#)

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