haskal nomad?

Modelling monads with a typeclass is stupid. There isn't one true monad for a given type. It makes no sense that when you use bind with lists you automatically get concatmap.

If you need multiple monad implementations for lists, you can do something like this:

data D a = A [a] | B [a] | C [a]

instance Monad D where
A xs >>= f = ...
B xs >>= f = ...
C xs >>= f = ...
...

I agree, though, it is ugly.