RE: [Caml-list] Interface(.mli) location

[David Allsopp <dra-news@metastack.com>]

SF Markus Elfring wrote:
> >>> a) Delete ./a.cmi as part of your build procedure.
> >>
> >> Can this design option trigger difficulties in your file system
> >> configuration?
> >
> > What sort of difficulties do you mean?
> 
> Do software build systems track the existence of such a generated file?
>
> Are you also concerned about a harder parallelisation there?
>
> > d/a.cmi may constrain values defined in ./a.ml and you won't get the
> > type-checking this way.
> 
> I would usually expect that these interface descriptions should be kept
> consistent to some degree.

Well yes, except that the compiler has two ways of interpreting an .ml file. Consistency would be maintained in either scenario - when there's a .ml and a .mli, the compiler will ensure that the interface of the Foo.ml and Foo.cmi unify, and you'll get a type error if they don't. Alternatively, if you don't have Foo.mli (so Foo.cmi and Foo.cmo are both generated) and you later try to link Foo.cmo with a module which expected it to comply with a different .cmi interface, you will get an "inconsistent assumptions about module Foo" link error (which admittedly would be very confusing, as that usually implies you have stale object files somewhere, not a broken build system). 

> > I was just floating ideas - if it's actually useful, raise a Mantis PR!
> 
> Will another official bug report or feature request help to improve the
> discussed situation?

It's just the next step if a change wants to made (or alternately coding up a suggestion and making a pull request on GitHub). I can certainly see that something along the lines of the -no-cmi option I suggest could be a useful addition, and it's in keeping with options like -impl, -intf and -intf-suffix, for example. But I'm just an observer :o)


David