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{-# LANGUAGE RankNTypes, TypeOperators, DefaultSignatures, FlexibleContexts, DeriveGeneric, DeriveAnyClass #-} | |
import Generics.OneLiner | |
import Data.Profunctor | |
import Data.Functor.Contravariant | |
import GHC.Generics | |
import Control.Applicative | |
import Unsafe.Coerce (unsafeCoerce) | |
type Lens s t a b = forall f. Functor f => (a -> f b) -> s -> f t | |
type Key t = forall x. Lens (t x) (t x) x x | |
constLens :: x -> Lens s t a b -> x | |
constLens x _ = x | |
newtype Keyed s t a b = Keyed { getKeyed :: Lens s t a b -> b } | |
instance Profunctor (Keyed s t) where | |
dimap f g (Keyed ix) = Keyed $ \l -> g (ix (l . (fmap g .) . (. f))) | |
instance GenericRecordProfunctor (Keyed s t) where | |
unit = Keyed (constLens U1) | |
mult (Keyed a) (Keyed b) = Keyed (\l -> a (l . fstl) :*: b (l . sndl)) | |
fstl :: Lens ((a :*: b) x) ((c :*: b') x') (a x) (c x') | |
fstl f (a :*: b) = (\c -> c :*: unsafeCoerce b) <$> f a | |
sndl :: Lens ((a :*: b) x) ((a' :*: c) x') (b x) (c x') | |
sndl f (a :*: b) = (\c -> unsafeCoerce a :*: c) <$> f b | |
class Repr f where | |
keyed :: (Lens s t a b -> b) -> Lens s t (f a) (f b) -> f b | |
default keyed :: (ADTRecord1 f, Constraints1 f Repr) => (Lens s t a b -> b) -> Lens s t (f a) (f b) -> f b | |
keyed f = getKeyed $ record1 (For :: For Repr) (\(Keyed g) -> Keyed $ keyed g) (Keyed f) | |
newtype Wrapped s t a b = Lens { runLens :: Lens s t a b } | |
newtype WrappedKey t = Key { runKey :: Key t } | |
repr :: Repr f => (Key f -> a) -> f a | |
repr f = keyed (\l -> f (runKey (unsafeCoerce (Lens l)))) id | |
index :: f a -> Key f -> a | |
index f l = getConst $ l Const f | |
data V3 a = V3 a a a deriving (Show, Generic1, Repr) | |
scale :: Num a => a -> V3 a -> V3 a | |
scale a v = repr (\l -> a * index v l) | |
diag :: V3 (V3 a) -> V3 a | |
diag m = repr (\l -> m `index` l `index` l) |
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