Right package:essence-of-live-coding

A mirror image of left. The default definition may be overridden with a more efficient version if desired.

Laws:

right' ≡ dimap swapE swapE . left' where
swapE :: Either a b -> Either b a
swapE = either Right Left
rmap Right ≡ lmap Right . right'
lmap (left f) . right' ≡ rmap (left f) . right'
right' . right' ≡ dimap unassocE assocE . right' where
assocE :: Either (Either a b) c -> Either a (Either b c)
assocE (Left (Left a)) = Left a
assocE (Left (Right b)) = Right (Left b)
assocE (Right c) = Right (Right c)
unassocE :: Either a (Either b c) -> Either (Either a b) c
unassocE (Left a) = Left (Left a)
unassocE (Right (Left b)) = Left (Right b)
unassocE (Right (Right c)) = Right c

Laws:

unright ≡ unleft . dimap swapE swapE where
swapE :: Either a b -> Either b a
swapE = either Right Left
rmap (either absurd id) ≡ unright . lmap (either absurd id)
unsecond . rmap (first f) ≡ unsecond . lmap (first f)
unright . unright ≡ unright . dimap unassocE assocE where
assocE :: Either (Either a b) c -> Either a (Either b c)
assocE (Left (Left a)) = Left a
assocE (Left (Right b)) = Right (Left b)
assocE (Right c) = Right (Right c)
unassocE :: Either a (Either b c) -> Either (Either a b) c
unassocE (Left a) = Left (Left a)
unassocE (Right (Left b)) = Left (Right b)
unassocE (Right (Right c)) = Right c