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

Returns the elements of the sequence up to a specified count.

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

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

// Signature:
Seq.take : int -> seq<'T> -> seq<'T>

// Usage:
Seq.take count source

count

Type: int

The number of items to take.

source

Type: seq<'T>

The input sequence.

Exception

Condition

ArgumentException

Thrown when the input sequence is empty.

ArgumentNullException

Thrown when the input sequence is null.

InvalidOperationException

Thrown when count exceeds the number of elements in the sequence.

The result sequence.

Seq.truncate returns as many items as the sequence contains instead of throwing an exception.

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

The following example demonstrates the use of Seq.take and contrasts the behavior with Seq.truncate.

let mySeq = seq { for i in 1 .. 10 -> i*i }
let truncatedSeq = Seq.truncate 5 mySeq
let takenSeq = Seq.take 5 mySeq

let truncatedSeq2 = Seq.truncate 20 mySeq
let takenSeq2 = Seq.take 20 mySeq

let printSeq seq1 = Seq.iter (printf "%A ") seq1; printfn "" 

// Up to this point, the sequences are not evaluated. 
// The following code causes the sequences to be evaluated.
truncatedSeq |> printSeq
truncatedSeq2 |> printSeq
takenSeq |> printSeq
// The following line produces a run-time error (in printSeq):
takenSeq2 |> printSeq
1 4 9 16 25 
1 4 9 16 25 36 49 64 81 100 
1 4 9 16 25 
1 4 9 16 25 36 49 64 81 100

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

F# Core Library Versions

Supported in: 2.0, 4.0, Portable

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