{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE PatternSynonyms #-}
{-# LANGUAGE ViewPatterns #-}
-----------------------------------------------------------------------------
-- |
-- Module      :  Data.Dynamic.Lens
-- Copyright   :  (C) 2012-2016 Edward Kmett
-- License     :  BSD-style (see the file LICENSE)
-- Maintainer  :  Edward Kmett <ekmett@gmail.com>
-- Stability   :  experimental
-- Portability :  non-portable
--
----------------------------------------------------------------------------
module Data.Dynamic.Lens
  ( AsDynamic(..)
  , pattern Data.Dynamic.Lens.Dynamic
  ) where

import Control.Exception
import Control.Exception.Lens
import Control.Lens
import Data.Dynamic

-- | Any 'Dynamic' can be thrown as an 'Exception'
class AsDynamic t where
  -- | This 'Prism' allows you to traverse the typed value contained in a
  -- 'Dynamic' where the type required by your function matches that
  -- of the contents of the 'Dynamic', or construct a 'Dynamic' value
  -- out of whole cloth. It can also be used to catch or throw a 'Dynamic'
  -- value as 'SomeException'.
  --
  -- @
  -- '_Dynamic' :: 'Typeable' a => 'Prism'' 'Dynamic'       a
  -- '_Dynamic' :: 'Typeable' a => 'Prism'' 'SomeException' a
  -- @
  _Dynamic :: Typeable a => Prism' t a

instance AsDynamic Dynamic where
  _Dynamic :: Prism' Dynamic a
_Dynamic = (a -> Dynamic) -> (Dynamic -> Maybe a) -> Prism' Dynamic a
forall b s a. (b -> s) -> (s -> Maybe a) -> Prism s s a b
prism' a -> Dynamic
forall a. Typeable a => a -> Dynamic
toDyn Dynamic -> Maybe a
forall a. Typeable a => Dynamic -> Maybe a
fromDynamic
  {-# INLINE _Dynamic #-}

instance AsDynamic SomeException where
  _Dynamic :: Prism' SomeException a
_Dynamic = p Dynamic (f Dynamic) -> p SomeException (f SomeException)
forall a. Exception a => Prism' SomeException a
exception(p Dynamic (f Dynamic) -> p SomeException (f SomeException))
-> (p a (f a) -> p Dynamic (f Dynamic))
-> p a (f a)
-> p SomeException (f SomeException)
forall b c a. (b -> c) -> (a -> b) -> a -> c
.(a -> Dynamic) -> (Dynamic -> Maybe a) -> Prism Dynamic Dynamic a a
forall b s a. (b -> s) -> (s -> Maybe a) -> Prism s s a b
prism' a -> Dynamic
forall a. Typeable a => a -> Dynamic
toDyn Dynamic -> Maybe a
forall a. Typeable a => Dynamic -> Maybe a
fromDynamic
  {-# INLINE _Dynamic #-}

pattern Dynamic :: (AsDynamic s, Typeable a) => a -> s
pattern $bDynamic :: a -> s
$mDynamic :: forall r s a.
(AsDynamic s, Typeable a) =>
s -> (a -> r) -> (Void# -> r) -> r
Dynamic a <- (preview _Dynamic -> Just a) where
  Dynamic a
a = AReview s a -> a -> s
forall b (m :: * -> *) t. MonadReader b m => AReview t b -> m t
review AReview s a
forall t a. (AsDynamic t, Typeable a) => Prism' t a
_Dynamic a
a