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Shows how to use an active pattern that will try to determine the format of an input value.
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open System // definition of the active pattern let (|Bool|Int|Float|String|) input = // attempt to parse a bool let sucess, res = Boolean.TryParse input if sucess then Bool(res) else // attempt to parse an int let sucess, res = Int32.TryParse input if sucess then Int(res) else // attempt to parse a float (Double) let sucess, res = Double.TryParse input if sucess then Float(res) else String(input) // function to print the results by pattern // matching over the active pattern let printInputWithType input = match input with | Bool b -> printfn "Boolean: %b" b | Int i -> printfn "Integer: %i" i | Float f -> printfn "Floating point: %f" f | String s -> printfn "String: %s" s // print the results printInputWithType "true" printInputWithType "12" printInputWithType "-12.1"
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active pattern
active pattern
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