I think that Haskell's parser combinator libraries, like Parsec, are clearly superior for most parsing tasks. Parsec is about as concise as a formal grammar, b

I think that Haskell's parser combinator libraries, like Parsec, are clearly superior for most parsing tasks. Parsec is about as concise as a formal grammar, but it is real code rather than a code generator, so you don't have the extra complexity of a parser-generator. Parsec parsers are type-safe, so there's no way that you'd get something back that wasn't a valid AST (or a parse error). Error handling is also quite good. Parsec in particular is not especially fast - there are other libraries like attoparsec and cereal (for binary serialization) which trade off some of the flexibility of parsec for improved performance. I think Haskell programmers mostly use these libraries, because they are clearly superior to the alternatives (for instance, you get a lot less interest in RegEx in Haskell-land, because when you have a really good parsing library there's much less reason to use them). C programs like SQLLite aren't using this approach because monads can't be expressed in the C type system, and there is no syntax sugar for monads in C, so Parsec would end up much less pleasant and much less safe than in Haskell.