[nerdponx]

Does Pandoc count? IIRC it implements CommonMark in a PEG.

[bd82]

I don't understand the question. I am not familiar with Haskell but from what I understand Pandoc is a group of hand crafted parsers (readers) for markup formats.

How does this relate to a discussion on the relevance of parser generators / libraries?

https://github.com/jgm/pandoc/tree/master/src/Text/Pandoc

[beojan]

If you check the Parser.hs file there, Pandoc uses Parsec.