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

Returns the first element of the sequence.

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

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

// Signature:
Seq.head : seq<'T> -> 'T

// Usage:
Seq.head source

Parameters

• source
  Type: seq<'T>

  The input sequence.

Exceptions

Return Value

The first element of the sequence.

Remarks

The first element of the source sequence is evaluated at each call. To avoid this reevaluation, you can create a cached version of a sequence by calling Seq.cache.

This function is named Head 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 shows how to use Seq.head.

let headItem = Seq.head [| 1 .. 10 |]
printfn "%d" headItem

Output

1

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

See Also

Reference

Collections.Seq Module (F#)

Microsoft.FSharp.Collections Namespace (F#)