I've been working on a new macro expander for Racket, and I'm starting to think that it will work. The new expander is not completely compatible with the current expander --- and that will be an issue if we eventually go forward with the change --- but most existing code still works.
Here's a report on my current experiment: http://www.cs.utah.edu/~mflatt/scope-sets/ The goals for a new expander are 1. to replace a complicated representation of syntax objects with a simpler one (and, as a result, avoid some performance and submodule-re-expansion problems that have been too difficult to fix with the current expander); 2. to find a simpler model of binding than the current one, so that it's easier to explain and reason about scope and macros; and 3. to implement the new expander in Racket instead of C. I have possibly succeeded on 1, possibly succeeded to some degree on 2, and temporarily given up on 3. (I know it sounds crazy to continue with a C implementation of macro expansion. Goals 1 and 2 were impossible for me without being able to try ideas at scale, though, and it was too daunting to tackle a full reimplementation of the expander and a restructuring of the VM at the same time. Continuing in the comfortable-for-only-me C environment was the way to make progress for now, and I look forward to tackling 3 as a next step.) I've pushed my current implementation to the "scope" branches of https://github.com/mflatt/racket https://github.com/mflatt/compiler [for `raco decompile` updates] I don't recommend bothering with the implementation, for now, unless you're especially interested in trying some examples. The current version builds well enough to run DrRacket, but there some build errors. I have a lot of work to do, still. -- You received this message because you are subscribed to the Google Groups "Racket Developers" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/racket-dev/20150226172633.2725A6501AA%40mail-svr1.cs.utah.edu. For more options, visit https://groups.google.com/d/optout.
