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AndreasHassing/active_pattern_single_case_du_trick.fsx

Created May 5, 2019 08:57
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active_pattern_single_case_du_trick.fsx
let (|UpperCase|) (str: string) = str.ToUpper()
// This blows my mind!
// thanks: https://youtu.be/yE88l29NOZw?t=151
let usedInAFunctionSignature (UpperCase(upper)) =
printfn "%s" upper
let usedLikeAMethod str =
let upper = (|UpperCase|) str
printfn "%s" upper
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AndreasHassing commented May 5, 2019

Thanks @7sharp9! :)

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AndreasHassing commented May 5, 2019

Immensely useful to be able to use single case active pattern like this in the method signature - sort of like a function signature level converter.

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