(one of the authors here): parser generators are generally good for one thing: parsing programming languages. For more complex formats, where you have to carry state around, or binary formats, they're extremely cumbersome to use. I often meet people that tell me they want the parser generator to end all parsers. But for most real world formats, you'll have to hack around the generator's limitations. Theoretically, parser combinators are less expressive, but they're just functions: you can write whatever you want inside a subparser, and integrate it with the rest. That approach works well, since we wrote a lot of complex parsers with nom.