Expose model, html, etc as public libraries

[jfeser]

I have a small tool (https://github.com/jfeser/odoc2docset) that depends on odoc. I use code from odoc.model to extract names and odoc.html to handle html generated by odoc. Could these libraries be exposed publicly? Right now I have a fork, but I'd rather just use the released version.

[aantron]

We can expose them with the understanding that their interface is not meant to be stable.

[jfeser]

That works for me. Thanks!

[aantron]

This seems to require giving the libraries globally unique names, like Odoc__model. The reason for the two underscores is that there are already modules with one. They come with the compiler and are part of ocamldoc.

This would make odoc's own code much uglier.

Still thinking about what to do here.

[aantron]

Ok, the sublibraries are now exposed. All the sublibraries are installed upon opam install odoc.

The library in directory model is installed as ocamlfind package odoc.model, and the module name is Odoc__model. The rest of the sublibraries follow the same pattern.

To do this, I had to, of course, rename module Model to Odoc__model, etc. To avoid ugly names, and changing all our code for this issue, I added an alias module in src/alias/odoc__alias.ml. This allows us to use the renamed modules under their previous, neat names:

odoc/src/alias/odoc__alias.ml

Lines 1 to 7 in 703b334

	module Compat = Odoc__compat
	module Html = Odoc__html
	module Loader = Odoc__loader
	module Model = Odoc__model
	module Odoc = Odoc__odoc
	module Parser_ = Odoc__parser
	module Xref = Odoc__xref

This alias module is -opened in all of odoc's code. It's a little bit dubious, but it's something we can undo quickly, if needed.

As mentioned, the interfaces of these libraries are unstable (including their names and existence), and we won't document them beyond what is needed by odoc. So, be careful :)