Is possible to parse "off-side" (indentation-based) languages with fparsec?

Question

I wish to use FParsec for a python-like language, indentation-based.

I understand that this must be done in the lexing phase, but FParsec don't have a lexing phase. Is possible to use FParsec, or, how can feed it after lexing?

P.D: I'm new at F#, but experienced in other languages

Indulge

Answer 1

Yes, it's possible.

Here is a relevant article by FParsec author. If you want to go deeper on the subject, this paper might worth a read. The paper points out that there are multiple packages for indentation-aware parsing that based on Parsec, the parser combinator that inspires FParsec.

FParsec doesn't have a separate lexing phase but instead it fuses lexing and parsing to a single phase. IMO indentation-aware parsing is better to be done with parser combinators (FParsec) than parser generators (fslex/fsyacc). The reason is that you need to manually track current indentation and report good error messages based on contexts.

Namedropping

Unfortunately SO is not allowing me to edit the question but if anyone finds out that the "relevant article" is dead and is interested to read it, it's in github: github.com/stephan-tolksdorf/fparsec/wiki/… – Regolith