module Data.Util where
import Control.Lens
import Data.Bifunctor
import Data.Semigroup
data STR a b c = STR { fst' :: !a, snd' :: !b , trd' :: !c}
deriving (Show,Eq,Ord,Functor)
instance Field1 (STR a b c) (STR d b c) a d where
_1 = lens fst' (\(STR _ b c) d -> STR d b c)
instance Field2 (STR a b c) (STR a d c) b d where
_2 = lens snd' (\(STR a _ c) d -> STR a d c)
instance Field3 (STR a b c) (STR a b d) c d where
_3 = lens trd' (\(STR a b _) d -> STR a b d)
data SP a b = SP !a !b deriving (Show,Eq,Ord,Functor)
instance (Semigroup a, Semigroup b) => Semigroup (SP a b) where
(SP a b) <> (SP c d) = SP (a <> c) (b <> d)
instance Field1 (SP a b) (SP c b) a c where
_1 = lens (\(SP a _) -> a) (\(SP _ b) c -> SP c b)
instance Field2 (SP a b) (SP a c) b c where
_2 = lens (\(SP _ b) -> b) (\(SP a _) c -> SP a c)
instance Bifunctor SP where
bimap f g (SP a b) = SP (f a) (g b)
type Two a = SP a a