It'd seem that (at least the online version of) Hoogle is totally broken
and useless. See, for example, the output when looking for:
       Monad m => m a -> (a -> m b) -> m b (i.e. (>>=)'s type)
over at:
http://haskell.org/hoogle/?q=Monad+m+%3D>+m+a+->+(a+->+m+b)+->+m+b

Data.Generics.Sche...   everywhere      :: (a -> a) -> a -> a
Data.Generics.Sche...   everywhere'     :: (a -> a) -> a -> a
Prelude.        ($)     :: (a -> b) -> a -> b
Prelude.        ($!)    :: (a -> b) -> a -> b
Data.Function.  ($)     :: (a -> b) -> a -> b
Prelude.        maybe   :: b -> (a -> b) -> Maybe a -> b
Data.Maybe.     maybe   :: b -> (a -> b) -> Maybe a -> b

... and so on. (>>=) isn't there at all!?