Consider standard functions based on Wlaschin example

[nicholasjhenry]

https://fsharpforfunandprofit.com/posts/recipe-part2/#the-railway-track-functions-complete-code

module EmailAddress =
type _T = EmailAddress of string
// create with continuation
let createWithCont success failure (s:string) =
if System.Text.RegularExpressions.Regex.IsMatch(s,@"^\S+@\S+\.\S+$")
then success (EmailAddress s)
else failure "Email address must contain an @ sign"
// create directly
let create s =
let success e = Some e
let failure _ = None
createWithCont success failure s
// unwrap with continuation
let apply f (EmailAddress e) = f e
// unwrap directly
let value e = apply id e

Result

// aka bimap 
let doubleMap successFunc failureFunc twoTrackInput =
match twoTrackInput with
| Success s -> Success (successFunc s)
| Failure f -> Failure (failureFunc f)