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Patterns.IfThenElse Active Pattern (F#)

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

Recognizes expressions that represent conditionals.

Namespace/Module Path: Microsoft.FSharp.Quotations.Patterns

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


// Signature:
( |IfThenElse|_| ) : (input:Expr) -> (Expr * Expr * Expr) option


input Type: Expr

The input expression to match against.

Return Value

The formal return type is (Expr * Expr * Expr) option. The option determines whether there is a match. In a pattern matching expression, the input is decomposed upon a match into a tuple of three expressions. The first element is the test condition. The second element is the expression after the then keyword that is executed if the test condition is true. The third element is the expression after the else keyword.


This function is named IfThenElsePattern in the .NET Framework assembly. If you are accessing the member from a .NET Framework 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

Quotations.Patterns Module (F#)

Microsoft.FSharp.Quotations Namespace (F#)

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