[bjoli]

Anything with parser combinators or PEG support. I had to learn PEG parsing for a project when I was a kid, and that has been one of my most useful skills.

[Yhippa]

Pardon, what is PEG?

[bjoli]

Parsing Expression Grammar. https://en.m.wikipedia.org/wiki/Parsing_expression_grammar

The examples section under definitions is the easiest way to understand them.