[Haskell-beginners] What's wrong with Haddock?!

[Baa]

I often hit such errors:

  parse error on input ‘-- ^ my doc-string is here’

when generate Haddock documentation. This happens on line like:

  instance Something UTCTime where
    some a = blahBlah -- ^ my doc-string is here

Sometimes such doc-strings are passing, sometimes - not. I can
understand what is the reason. Is there some rule how to format such
kind of doc-strings?


===
Cheers, Paul