Hello, Olaf. I have some distrust of elegant solutions (one of them are C.P. libs). I am a mathematician, I trust a lot in elegance and beauty. As long as the performance penalty is not prohibitively large, I'd prefer a beautiful implementation over an aggressively optimized one. At least when the code does not live in some real-time system. Certainly there are cases where you absolutely need speed or low memory footprint.
For example, I read that they have problems with memory consuming (famous article about arrow-based parsers), also your example (my own experience includes a lot of tricks which I don't like)... So (but this is my IMHO) for big and serious project with parsing of something complex I will use bindings to good known parser libraries... I consider Parsec and it descendants good and known. I could not write something like that. Currently I rely on megaparsec because of its informative error messages, knowing that I can switch to one of the siblings without much effort when I need more speed.
Maybe something like this: https://github.com/markwright/antlrc. Btw, Happy looks still live (https://github.com/simonmar/happy) Have you used any of the above?
I use "Read"-style parsers for small constructions only, so fail of such small parser is only case where error is producing and I do it explicitly (as biggest example: header of Git patch).
Olaf, what do you think about 1. http://hackage.haskell.org/package/frisby
2. http://tanakh.github.io/Peggy Notice that in the examples of bothy frisby and peggy, parsing a number only parses a string of digits, then passes it to 'read', i.e. another
Frisby looks quite old, as it has idiosyncratic combinators for stuff now in Data.Functor. I've never used it, so I can't tell what its strengths are. Can you? parser. Is that efficient, elegant parsing? I'm nevertheless intrigued by PEG parsers, because I once read about the connection between grammars and compression: A set of production rules can be quite a bit smaller than the actual text. This turns parsing upside down: The text is constant, the grammar unknown. Olaf