Re: [Caml-list] Why should I use .mli files?

["Daniel Bünzli" <daniel.buenzli@erratique.ch>]

Le mardi, 30 octobre 2012 à 03:36, Francois Berenger a écrit :

> > For me, a program that lacks mli files means lack of design, abstraction and documentation and hence equates with rubbish.
>  
>  
> Thanks for the compliment.
Oh don't take it personally it also happens to me.  

> To my defence, my main programming goal because of my employer
> and colleagues is to deliver fast and correct (software) in order to
> investigate research ideas.
> We don't deliver libraries or things targeting at a wide developer


I personnally find none of these arguments very compelling. And if you are interested in correct software, you better have a good/understandable design and mli files help you with that.

> > At that moment simple things like being able to distinguish between  
> functions/types that are local to a module and those that are used by  
> other part of the program is immensely useful.
>  
> Well, if I want to know this, I change the function parameters
> and let the compiler tell me where it was used with the initial parameters.
> I also quite know my swiss knives (egrep and co).

I don't really think that this approach scales if you need to get in touch with a code base that you didn't write --- and remember, for most persons, after a year, your own code looks like code that you didn't write yourself.

> OK, so you too are a top-down design practitioner
> and use .mli files to this end.

Well not necessarily, I mean things are no so clear cut, design informs implementation and vice-versa. It's not as if I necessarily get the mli files right from the start and then just implement them and everything works, it's a refinement process. It also happens to me start the ideas in an ml files and then gradually split it into different modules when it becomes clear what functions/types form the modular units of the programs.  

What is essential to me with mli files is that it makes you think about your program modularity. And modularity is an essential tool for both program understanding and maintenance.

Best,

Daniel