[yawaramin]

Yeah, but programming is the business of building little tools to help you build what you actually want to build, over and over again. E.g., you might have some API calls in your code and need to implement an error handler on some of them. You could repeat the error handler code on all of them, or you could extract it out to a generic function and just use it as a wrapper for the others:

    let call1 arg = ...
    let call2 arg = ...

    let error_handler call arg = ...

    let call1 = error_handler call1
    let call2 = error_handler call2

Python made this kind of technique famous, but languages with generics can do it pretty well too.