{-# LANGUAGE TypeFamilies #-} {-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE UndecidableInstances #-} {-# LANGUAGE MultiParamTypeClasses #-} ----------------------------------------------------------------------------- -- | -- Module : Control.Lens.Internal.Review -- Copyright : (C) 2012-2014 Edward Kmett -- License : BSD-style (see the file LICENSE) -- Maintainer : Edward Kmett <ekmett@gmail.com> -- Stability : provisional -- Portability : non-portable -- ---------------------------------------------------------------------------- module Control.Lens.Internal.Review ( -- * Internal Classes Reviewable -- * Reviews , retagged ) where import Data.Bifunctor import Data.Profunctor import Data.Void -- | This class is provided mostly for backwards compatibility with lens 3.8, -- but it can also shorten type signatures. class (Profunctor p, Bifunctor p) => Reviewable p instance (Profunctor p, Bifunctor p) => Reviewable p ------------------------------------------------------------------------------ -- Review: Reviewed ------------------------------------------------------------------------------ -- | This is a profunctor used internally to implement "Review" -- -- It plays a role similar to that of 'Control.Lens.Internal.Getter.Accessor' -- or 'Const' do for "Control.Lens.Getter" retagged :: (Profunctor p, Bifunctor p) => p a b -> p s b retagged = first absurd . lmap absurd