Switch from flextGL to gl package.

[Noeda]

Should not duplicate efforts, no, yes? gl didn't exist when Caramia was started. It would give us the raw bindings and as far as API goes you can use it in a very similar way to the FlextGL way.
https://github.com/ekmett/gl

I'll do this at some point.

[abbradar]

I've wanted to ask if channelized-opengl work has been abandoned, looks like this is the answer ^_^.
Looked at the code: they have the same IORef approach as us, just exploit laziness more to avoid flextInit-like function AFAIU. They also have a wrapper for getProcAddress which looks more cross-platform-ey.
An outline to what likely needs to be done:

• Check needed extensions in withContext; they have corresponding Bools for that.
• Move getGLVersion inside our code.

Other than that, just resolve naming issues if any and it's done. Looks good!

Upd: we shouldn't even check anything in withContext actually, just use these Bools where needed.

[Noeda]

Yeah, I abandoned channelized-opengl. I was going to attempt to hide the fact that you have to do all your OpenGL work in a single bounded thread (by communicating with channels between OpenGL thread and other threads, thus the name). I put a phantom type on everything and it turned out to be a bad idea. Extra safety is nice and I did have re-entrant function pointers but I felt it was not worth the extra type baggage.