The act of parsing involves uncovering the structure of a sentence based on grammar, highlighting the complexities and challenges involved. While parsing for programming languages has advanced over the years, the process of grammar composition, combining two grammars to parse text in a new language, presents unique obstacles. Issues such as tokenization, fine-grained composition, and ambiguity arise, with traditional parsing algorithms like LL and LR falling short. The emergence of Packrat / PEG parsing offers a promising solution, but limitations such as lack of left recursion and potential for unexpected behavior remain. Parsing, while considered a solved problem by many, reveals ongoing complexities and possibilities for improvement in language composition.
https://tratt.net/laurie/blog/2011/parsing_the_solved_problem_that_isnt.html