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

[Oliver Bandel <oliver@first.in-berlin.de>]

Am 31.10.2012 um 02:44 schrieb Daniel Bünzli <daniel.buenzli@erratique.ch>:

> Francois Berenger a écrit :
> > On 10/30/2012 09:28 PM, Daniel Bünzli wrote:
> >> I personnally find none of these arguments very compelling.
> >
> > "don't take it personally" ;)
> 
> Well... really !
> 
>> In the first place, I don't want to write those .mli files as the
>> compiler can infer them for me automatically (I'm lazy).
> 
> Sure, but it infers the most flexible one and there are many case where this is not desired. For example if you want to use typing tricks for correctness like phantom types you must write mli files.
> 
> And at the risk of repeating myself, knowing by a quick glance what is internal/external to a module is also very useful information, e.g. if you intend to rewrite its functionality. The compiler cannot know what's really important for the clients of the module, it exports everything. Consider mli files as cheap documentation.
[...]

The point, some peoplembrought in, was, that after changing the ml-file,
the mli is thenold one nevertheless. This also, means, that ocamlc -i
will not help here.
Thenmli file first mustbbe removed or renamed, to get the output for the changed
ml-file.
This also has annoyed me sometimes, when I wanted to to get the new
default signature.

A solution to this problem could be, to have a --force flag, so that
ocamlc -i --force would print the default-signature of the raw ml-file,
as if the mli file corrosponding to it would not exist.
Then the forced ocamlc would print the whole sig of the ml.
One could pick out the new stuff then.

Or a   ocamlc -i --force --diff
could print a diff of the signatures of the raw ml-file with unused mli
to the signature which is forced by the mli-file.

In this way the needed functionality of generating mli-content would be
achieved, without changing the classical behaviour of the mli-files.
And an implementation seems also to be also comparingly easy.

And I would not insist on "--force" and "--diff" as being best choices,
but it was just to explain what is meant as proposal.


Best regards,
   Oliver