On Tue, Apr 28, 2009 at 5:33 PM, Michael Vanier <mvanier42@gmail.com> wrote:

Tony Morris wrote:

Michael Vanier wrote:
  

I've stumbled upon a structure that is like a weaker version of a
monad, one that supports return and >> but not >>=.  Has anyone seen
this before, and if so, does it have a standard name?

Mike


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Are you sure it supports
(>>) :: m a -> m b -> m b

and not
mplus :: m a -> m a -> m a ?

  

Yeah, you're right.  It's basically a monad where the type a is fixed to be (), so you just have

(>>) :: m () -> m () -> m ()

That's a monoid.

Luke