parsley VS scala.meta

Or alternatively my own https://github.com/j-mie6/parsley for a more Haskell-style library - it has a wiki that discusses a lot of the main ideas, including how to deal with Def/Val/lazy val

Depends on your existing knowledge of Haskell and stuff like monads, applicatives, etc. I haven't gotten around to writing a tutorial for Parser Combinators yet (I'd actually like to write a book about them at some point) in Haskell, but I do have this wiki here ( https://github.com/j-mie6/Parsley/wiki/Guide-to-Parser-Combinators ) for my parser combinator library in Scala, that might be of some help. A Haskell version of a lot of the later material there can be found in this paper https://dl.acm.org/doi/10.1145/3471874.3472984. The paper assumes some familiarity with Parser Combinators, the wiki does not (but is written in Scala): it's the resource I use to teach my 2nd year undergrads about Parser Combinators for their compilers project. It doesn't talk about monads/applicatives at all. I'm more than happy to answer any questions you have about either of those two.

I just wrote a small generator for a personal project using scalameta. It might be worth doing just for the learning experience, I thought it was a blast to use.

I have successfully installed metals on emacs as per the instructions on scalameta.org - things like syntax highlighting and jump to definiton work, and lsp-metals-doctor-run shows mostly green ticks.