[Haskell-cafe] name for monad-like structure?

Luke Palmer lrpalmer at gmail.com
Tue Apr 28 19:19:51 EDT 2009

On Tue, Apr 28, 2009 at 4:54 PM, Michael Vanier <mvanier42 at gmail.com> 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?

That is a strange structure.  The type parameter is hardly doing anything:
whenever you compose two of them together, you have no choice but to ignore
the left one.

Let's call your structure S.  It's likely that S a is isomorphic to a pair
(m, a), where m is some monoid.

I would see if you can restate your problem in terms of a monoid.

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