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Patterns.UnionCaseTest Active Pattern (F#)

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

Recognizes expressions that represent an operation that tests whether a value is of a particular union case.

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

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


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


input Type: Expr

The input expression to match against.

Return Value

The formal return type is (Expr * UnionCaseInfo) option. The option indicates whether the input results in a match. In a pattern matching expression, the input is decomposed into a tuple of two elements. The first element is the expression that represents the target of the test and the second element is the UnionCaseInfo object that represents the union case.


This function is named UnionCaseTestPattern 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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