Re: Monoid for ZipList

I aim to make the semantic consistent compared to that of other type classes (here Maybe). Also note that your instance is identical to upcoming Ap, as Ap (ZipList a). I also aim to make Monoids as diverse as possible. -----Original Message----- From: "Andrew Martin" To: "박신환"; Cc: "Haskell Libraries"; Sent: 2018-05-03 (목) 21:05:24 Subject: Re: Monoid for ZipList There is another possible instance. We can instead write: instance Semigroup a => Semigroup (ZipList a) where (<>) = liftA2 (<>) instance Monoid a => Monoid (ZipList a) where mempty = pure mempty This behaves differently, and it is also law-abiding.