Consider Citron for parsing

[dabrahams]

I found this to be a pleasure to use and it reduced the amount of code in my project considerably over the corresponding hand-coded parser.

[kyouko-taiga]

The current implementation uses a custom data structure as it parses declarations to configure scopes (i.e., assign Decl.parentDeclSpace). Would it be possible to reproduce that behavior with Citron?

I'm also a little concerned about error messages. The current implementation purposely parses a superset of Val's actual grammar so that the parser can identify common errors (e.g., missing annotation in a parameter declaration, method qualifier on free function, etc.). How would you handle this kind of errors with Citron?