So the author isn't reinventing the wheel. I should have explained that Railway programming isn't supposed to replace doing try/catch, it's typically best suited for scenarios where errors are not exceptional. It works best when errors are occurring very regularly, are part of the logic of the system, and where you want to ensure the programmer takes advantage of F#'s exhaustive pattern matching to ensure developers account for all the scenarios.

In this scenario, performance matters because you want the creation of the error (these aren't exceptions) to be relatively cheap because it is a regular part of the system.

In these scenarios, using exceptions would be abusing exceptions, because exceptions are typically supposed to be exceptional.