If you're really interested in this, I'd encourage you to take some actual Parsec code and make this change, then compare the two for readability. My guess is that while it's conceptually nice, you'll find in practice it hampers readability more than it helps.
Thanks for the constructive suggestion - I don't have much invested in this particular little debate so I'm not sure I'll take the time to do that, but it's definitely a good idea.
I will say that in my opinion, the alternative in the reply above this (which I can't reply to) looks fairly nice, is clearer, and not even a little bit harder to follow. But I'll allow that as a very casual Haskell programmer, my opinions about Haskell are probably not particularly valid.
