[zelphirkalt]

Many projects wish they had a proper grammar. When a project turns useful and people want to port it, or support it on other platforms, a grammar makes that job much easier.

I am not quite sure what you mean by having a recursive descent parser, because you can write one manually, or you can generate one from a grammar, which would have the additional benefits of having a grammar. I recommend having a grammar.

[vanviegen]

I like writing parsers, and nowadays just use handwritten recursive descent functions, using a couple of simple utility functions. It is easy to reason about and flexible. I do start each parsing function with a comment stating the informal grammar the function should parse (and LLM autocomplete usually types the rest of the function).

With regard to portability: I've found cross-language parser generators especially unpleasant to work with. Instead, I just implement the parser in a language that runs on all platforms I care about.