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

Returns the sum of the results generated by applying the function to each element of the sequence.

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

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

// Signature:
Seq.sumBy : ('T -> ^U) -> seq<'T> -> ^U (requires ^U with static member (+) and ^U with static member Zero)

// Usage:
Seq.sumBy projection source

Parameters

• projection
  Type: 'T -> ^U

  A function to transform items from the input sequence into the quantity that will be summed.

• source
  Type: seq<'T>

  The input sequence.

Return Value

The sum of the results of applying the projection function to each element of the sequence.

Remarks

The generated elements are summed using the + operator and Zero property associated with the generated type.

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

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#)