Emacs has a mechanism for customizing the editing behaviour of buffers based on their major mode. A buffer can only have one major mode, but in literate styles of programming and proving we want to mix program text with documentation in a single file. A way of multiplexing major modes is needed, so that different regions of a buffer can be edited in different modes. One approach may be to use "views" onto untangled buffers, although it isn't clear how search and replace, etc, should behave in this case.
The MMM mode Emacs add-on allows multiple-modes in a similar way, and was originally designed for the situation where you have a script embedded in an HTML page. This project might try applying MMM mode for Proof General with Coq and Isabelle/Isar, as a feasibility demonstration.
Skills: A passion for Emacs and Emacs Lisp.
Proposer: David Aspinall.