open System.Text.RegularExpressions

// the definition of the active pattern
let (|Regex|_|) regexPattern input =
    // create and attempt match regular expression
    let regex = new Regex(regexPattern)
    let regexMatch = regex.Match(input)
    // return either Some or None
    if regexMatch.Success then
        Some regexMatch.Value
    else
        None

// function to print the results by pattern
// matching over different instances of the
// active pattern
let printInputWithType input =
    match input with
    | Regex "$true|false^" s -> printfn "Boolean: %s" s
    | Regex @"$-?\d+^" s -> printfn "Integer: %s" s
    | Regex "$-?\d+\.\d*^" s -> printfn "Floating point: %s" s
    | _ -> printfn "String: %s" input

// print the results    
printInputWithType "true"
printInputWithType "12"
printInputWithType "-12.1"