2008/8/29 Philip Weaver <philip.weaver@gmail.com>:

> It sounds like you tried to redefine (>>) and (>>=) and make 'do' use the
> new definitions.  This is not possible, regardless of what types you give
> (>>) and (>>=).

Watch out for rebindable syntax:
http://www.haskell.org/ghc/docs/latest/html/users_guide/syntax-extns.html#rebindable-syntax

At first reading, I thought that -XNoImplicitPrelude was required to
turn this on. But now I'm not sure: it seems that if you hide
Prelude.>>= and Prelude.return, that ought to be enough to make do
notation work with your alternative definitions. I'm not at home, so I
can't try this right now.

--
-David