-- |
-- Module: Data.Typeable.Optics
-- Description: Optics for working with 'Typeable'.
--
module Data.Typeable.Optics
  ( _cast
  , _gcast
  ) where

import Data.Typeable
import Data.Maybe

import Optics.AffineTraversal

-- | An 'AffineTraversal'' for working with a 'cast' of a 'Typeable' value.
_cast :: (Typeable s, Typeable a) => AffineTraversal' s a
_cast :: AffineTraversal' s a
_cast = AffineTraversalVL s s a a -> AffineTraversal' s a
forall s t a b.
AffineTraversalVL s t a b -> AffineTraversal s t a b
atraversalVL (AffineTraversalVL s s a a -> AffineTraversal' s a)
-> AffineTraversalVL s s a a -> AffineTraversal' s a
forall a b. (a -> b) -> a -> b
$ \forall r. r -> f r
point a -> f a
f s
s -> case s -> Maybe a
forall a b. (Typeable a, Typeable b) => a -> Maybe b
cast s
s of
  Just a
a  -> s -> Maybe s -> s
forall a. a -> Maybe a -> a
fromMaybe ([Char] -> s
forall a. HasCallStack => [Char] -> a
error [Char]
"_cast: recast failed") (Maybe s -> s) -> (a -> Maybe s) -> a -> s
forall b c a. (b -> c) -> (a -> b) -> a -> c
. a -> Maybe s
forall a b. (Typeable a, Typeable b) => a -> Maybe b
cast (a -> s) -> f a -> f s
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> a -> f a
f a
a
  Maybe a
Nothing -> s -> f s
forall r. r -> f r
point s
s
{-# INLINE _cast #-}

-- | An 'AffineTraversal'' for working with a 'gcast' of a 'Typeable' value.
_gcast :: (Typeable s, Typeable a) => AffineTraversal' (c s) (c a)
_gcast :: AffineTraversal' (c s) (c a)
_gcast = AffineTraversalVL (c s) (c s) (c a) (c a)
-> AffineTraversal' (c s) (c a)
forall s t a b.
AffineTraversalVL s t a b -> AffineTraversal s t a b
atraversalVL (AffineTraversalVL (c s) (c s) (c a) (c a)
 -> AffineTraversal' (c s) (c a))
-> AffineTraversalVL (c s) (c s) (c a) (c a)
-> AffineTraversal' (c s) (c a)
forall a b. (a -> b) -> a -> b
$ \forall r. r -> f r
point c a -> f (c a)
f c s
s -> case c s -> Maybe (c a)
forall k (a :: k) (b :: k) (c :: k -> *).
(Typeable a, Typeable b) =>
c a -> Maybe (c b)
gcast c s
s of
  Just c a
a  -> c s -> Maybe (c s) -> c s
forall a. a -> Maybe a -> a
fromMaybe ([Char] -> c s
forall a. HasCallStack => [Char] -> a
error [Char]
"_gcast: recast failed") (Maybe (c s) -> c s) -> (c a -> Maybe (c s)) -> c a -> c s
forall b c a. (b -> c) -> (a -> b) -> a -> c
. c a -> Maybe (c s)
forall k (a :: k) (b :: k) (c :: k -> *).
(Typeable a, Typeable b) =>
c a -> Maybe (c b)
gcast (c a -> c s) -> f (c a) -> f (c s)
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> c a -> f (c a)
f c a
a
  Maybe (c a)
Nothing -> c s -> f (c s)
forall r. r -> f r
point c s
s
{-# INLINE _gcast #-}