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Operators.( <|| )<'T1,'T2,'U> Function (F#)

Den Delimarsky|Last Updated: 7/19/2016
1 Contributor

Apply a function to two values, the values being a pair on the right, the function on the left

Namespace/Module Path: Microsoft.FSharp.Core.Operators

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


// Signature:
( <|| ) : ('T1 -> 'T2 -> 'U) -> 'T1 * 'T2 -> 'U

// Usage:
func <|| (arg1, arg2)


func Type: 'T1 -> 'T2 -> 'U

The function.

arg1 Type: 'T1

The first argument.

arg2 Type: 'T2

The second argument.

Return Value

The function result.


The following example demonstrates the use of the <|| operator.

let append string1 string2 = string1 + "." + string2

let result1 = append <|| ("abc", "def")
printfn "append <|| (\"abc\", \"def\") gives %A" result1

let toUpper (string1:string) (string2:string) = string1.ToUpper(), string2.ToUpper()

// Reverse pipelines require parentheses.
let result2 = append <|| (toUpper <|| ("abc", "def"))

printfn "result2: %A" result2


append &lt;|| ("abc", "def") gives "abc.def"
result2: "ABC.DEF"


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

Core.Operators Module (F#)

Microsoft.FSharp.Core Namespace (F#)

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