Fix variable name m31-ml-variable-rx in andromeda-smie.el

[mikeshulman]

The current m31-meta-variable-rx gives File mode specification error: (void-variable m31-meta-variable-rx). Since m31-ml-variable-rx exists and seems to work, I guessed that it was probably the correct name.

[mikeshulman]

(Although now I instead get a whole screen of Warnings from smie.)

[mikeshulman]

Huh. I swear this wasn't happening before I submitted the PR, but now with this change (and m31-smart-indent turned on) I get immense slowdowns with a bunch of "looking at" and "fall-through" messages. I guess maybe andromeda-smie doesn't quite work yet. But eri also seems to be broken, so I guess for now I'm going to (remove-hook 'm31-mode-hook 'm31--indentation-setup). I totally understand that #467 is way lower priority than actually writing Andromeda, but I'm curious what you all are using to edit AML code right now?

[andrejbauer]

I gave up on the SMIE thing, I think @haselwarter hacked on it a while ago. If you turn on OCaml mode it's not so bad. I might create a simple mode based on the OCaml mode that does correct highlighting, a bit like this eff-mode.el. If you have the energy to do it, replace the keywords in eff-mode.el by those listed in parser/lexer.ml and you'll have a simple andromeda-mode.eff. It won't work perfectly (it will get confused by extra end at the end of a match -- that's another debate, whether we should get rid of it).

[andrejbauer]

The long-term solution is to provide a proof-general interface, of course.

[andrejbauer]

See #505 for a simple Emacs mode for Andromeda.