[Haskell-cafe] From monads to monoids in a small category

[Alberto G. Corona]

"Monads are monoids in the category of endofunctors"

This Monoid instance for the endofunctors of the set of all  elements
of (m a)   typematch in Haskell with FlexibleInstances:

instance Monad m => Monoid  (a -> m a) where
   mappend = (>=>)   -- kleisly operator
   mempty  = return

The article can be found here:

http://haskell-web.blogspot.com.es/2012/07/from-monads-to-monoids-in-small.html

I would appreciate some comments.