Developer doc: describe debug process

[WardBrian]

It would be useful to add a write up to the stanc3 developer documentation on the use of print_s, s-expressions, and other debugging utilities we use while working on the compiler.

I don't really use ocamldebug personally, but if anyone has experience with it and stanc3 that would also be helpful

[WardBrian]

Useful links:

• Core_kernel.Debug
• Ocamldebug
• Print_s (this isn't really explained, but print_s [%sexp (e : typed_expression)] will print the s-expression form of e, or any type with the sexp derivation. It's a shorthand for print_endline (Sexp.to_string (Ast.sexp_of_typed_expression e))

[yizhang-yiz]

It'd also help if we add some Menhir options such as --explain that I often use to locate conflicts.

[WardBrian]

We actually have —explain enabled by default, but the results end up in a rather unhelpful place (./_build/default/src/frontend)

There’s definitely a lot more stuff we can document on the getting started page about dune and Menhir. Those are both really common in the OCaml ecosystem though

[yizhang-yiz]

but the results end up in a rather unhelpful place (./_build/default/src/frontend)

TIL. Thanks!