It's a pity that the thing has to get reimplemented all over so many times. For example, you'd think you could reuse PostgreSQL's parser, but its code is autogenerated and riddled with side effects:

https://github.com/postgres/postgres/blob/master/src/backend...

We've a lot of got languages and usually their parsers are tightly coupled, basically forcing people to reimplement them if you want a flexible parser. I'd say it would be great if we had one parsing library for each language, ideally used at its core. I think that would greatly simplify implementing linters, static analysers and maybe even tools that generate code. Also, perhaps this would enable even more cooler hacks?