[Haskell-cafe] About mplus

ok ok at cs.otago.ac.nz
Wed Sep 5 02:49:19 EDT 2007

On 5 Sep 2007, at 6:16 pm, Henning Thielemann wrote:
> I think it is very sensible to define the generalized function in  
> terms of the specific one, not vice versa.

The specific point at issue is that I would rather use ++ than
`mplus`.  In every case where both are defined, they agree, so
it is rather frustrating to be blocked from using an operator
which would otherwise have been appropriate.

Of course it is not a show-stopper; I can simply make something
else up.

I am a little puzzled that there seems to be no connection between
MonadPlus and Monoid.  Monoid requires a unit and an associative
binary operator.  So does MonadPlus.  Unfortunately, they have different
names.  If only we'd had (Monoid m, Monad m) => MonadPlus m...

More information about the Haskell-Cafe mailing list