I don't write Haskell, but the documentation on that page almost made me wish I did.
Other projects, take notes.
Other projects, take notes.
That's unfair. Documentation writing is usually the last item for software developers. Full stop.
But, as dons pointed out, crappy docs is not limited to Haskell by any means.
If you want to see your project gain traction it has to be stupid easy for people to jump in and start playing, and solid Web site with serious docs is a big win there (as are project generators and copious examples).