module Data.Vinyl.Lens
( module Control.Lens
, RLens
, rLens
, rGet
, rPut
, rMod
) where
import Data.Vinyl.Field
import Data.Vinyl.Rec
import Data.Vinyl.Witnesses
import Control.Lens
import Control.Monad.Identity
type RLens sy t = IElem (sy ::: t) rs => SimpleLens (PlainRec rs) t
rLens :: (sy ::: t) -> RLens sy t
rLens f = rLens' f implicitly
rGet = view . rLens
rPut = set . rLens
rMod = over . rLens
rLens' :: (r ~ (sy ::: t)) => r -> Elem r rs -> SimpleLens (PlainRec rs) t
rLens' _ Here = lens (\(x :& xs) -> runIdentity x) (\(_ :& xs) x -> Identity x :& xs)
rLens' f (There p) = rLensPrepend $ rLens' f p
rLensPrepend :: SimpleLens (PlainRec rs) t -> SimpleLens (PlainRec (l ': rs)) t
rLensPrepend l = lens (\(x :& xs) -> view l xs) (\(a :& xs) x -> a :& (set l x xs))