pcfwik

There was an interesting discussion two years ago regarding nonobvious issues with PEGs:

https://news.ycombinator.com/item?id=30414683

https://news.ycombinator.com/item?id=30414879

I spent a year or two working with PEGs, and ran into similar issues multiple times. Adding a new production could totally screw up seemingly unrelated parses that worked fine before.

As the author points out, Earley parsing with some disambiguation rules (production precedence, etc.) has been much less finicky/annoying to work with. It's also reasonably fast for small parses even with a dumb implementation. Would suggest for prototyping/settings when runtime ambiguity is not a showstopper, despite the remaining issues described in the article re: having a separate lexer.

Also possible to do directly in the "safe" type system, without messing around with /proc/mem: https://zyedidia.github.io/blog/posts/5-safe-transmute/