monadplus - w3toppers.com

Distinction between typeclasses MonadPlus, Alternative, and Monoid?

MonadPlus and Monoid serve different purposes. A Monoid is parameterized over a type of kind *. class Monoid m where mempty :: m mappend :: m -> m -> m and so it can be instantiated for almost any type for which there is an obvious operator that is associative and which has a unit. … Read more

Confused by the meaning of the ‘Alternative’ type class and its relationship to other type classes

To begin with, let me offer short answers to each of these questions. I will then expand each into a longer detailed answer, but these short ones will hopefully help in navigating those. No, Alternative and Monoid don’t mean different things; Alternative is for types which have the structure both of Applicative and of Monoid. … Read more