On Wed, 5 Sep 2007, ok wrote:
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.
What is your application, where you need (++) frequently? Today I like that (++) points me to the fact, that we are working on lists. Ok, I would be fine, if (++) would be a method for all sequence types. But for MonadPlus, this is too general for my taste.
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...
Monoid is of kind * MonadPlus is of kind * -> *