1.1

• Split Semialign into Semialign and Zip.
• Rename old Zip into Repeat
• i.e. current main hierarchy is
• Remove malign, use salign or alignWith mappend where Monoid is necessary.
• Add Option instances

instance Functor f => Semialign f where
    alignWith :: (These a b -> c) -> f a -> f b -> f c

instance Semialign f => Align f where
    nil :: f a

instance Semialign f => Zip f where
    zipWith :: (a -> b -> c) -> f a -> f b -> f c

instance Zip f => Repeat f where
    repeat :: a -> f a

This biased choice, that Semialign is a super-class of Zip is motivated by the fact that

• There's no Semialign-like class anywhere else, yet
• Zip and Repeat are Apply (from semigroupoids) and Applicative with slightly more laws. I If you need only Repeat class, and your type isn't Alingable, maybe using Applicative is enough?

1

Split out of these package.