It's usually a matter of taste. You shouldn't have types or values with 20 characters, but you also shouldn't do C-style "no vowels" naming.

It's also worth mentioning that the "-- ^ comment" syntax is so that Haddock, Haskell's automatic documentation generator, can display the comments in the HTML documentation. Example: http://hackage.haskell.org/package/Cabal-1.18.1.2/docs/Distr...