Move Zoomed/Magnified out of Internal

In order to define a Zoom or Magnify instance of a non-lens type, it is
necessary to instantiate Zoomed or Magnified, so they belong in the
principal module.

src/Control/Lens/Internal/Zoom.hs

@@ -1,7 +1,6 @@
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE Safe #-}
 {-# LANGUAGE TypeFamilies #-}
-{-# LANGUAGE KindSignatures #-}
 {-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE UndecidableInstances #-}
 
@@ -19,15 +18,13 @@
 module Control.Lens.Internal.Zoom
   (
   -- * Zoom
-    Zoomed
-  , Focusing(..)
+    Focusing(..)
   , FocusingWith(..)
   , FocusingPlus(..)
   , FocusingOn(..)
   , FocusingMay(..), May(..)
   , FocusingErr(..), Err(..)
   -- * Magnify
-  , Magnified
   , Effect(..)
   , EffectRWS(..)
   ) where
@@ -36,41 +33,11 @@ import Control.Applicative
 import Control.Category
 import Control.Comonad
 import Control.Monad.Reader as Reader
-import Control.Monad.Trans.State.Lazy as Lazy
-import Control.Monad.Trans.State.Strict as Strict
-import Control.Monad.Trans.Writer.Lazy as Lazy
-import Control.Monad.Trans.Writer.Strict as Strict
-import Control.Monad.Trans.RWS.Lazy as Lazy
-import Control.Monad.Trans.RWS.Strict as Strict
-import Control.Monad.Trans.Error
-import Control.Monad.Trans.Except
-import Control.Monad.Trans.List
-import Control.Monad.Trans.Identity
-import Control.Monad.Trans.Maybe
 import Data.Functor.Bind
 import Data.Functor.Contravariant
 import Data.Semigroup
 import Prelude hiding ((.),id)
 
-------------------------------------------------------------------------------
--- Zoomed
-------------------------------------------------------------------------------
-
--- | This type family is used by 'Control.Lens.Zoom.Zoom' to describe the common effect type.
-type family Zoomed (m :: * -> *) :: * -> * -> *
-type instance Zoomed (Strict.StateT s z) = Focusing z
-type instance Zoomed (Lazy.StateT s z) = Focusing z
-type instance Zoomed (ReaderT e m) = Zoomed m
-type instance Zoomed (IdentityT m) = Zoomed m
-type instance Zoomed (Strict.RWST r w s z) = FocusingWith w z
-type instance Zoomed (Lazy.RWST r w s z) = FocusingWith w z
-type instance Zoomed (Strict.WriterT w m) = FocusingPlus w (Zoomed m)
-type instance Zoomed (Lazy.WriterT w m) = FocusingPlus w (Zoomed m)
-type instance Zoomed (ListT m) = FocusingOn [] (Zoomed m)
-type instance Zoomed (MaybeT m) = FocusingMay (Zoomed m)
-type instance Zoomed (ErrorT e m) = FocusingErr e (Zoomed m)
-type instance Zoomed (ExceptT e m) = FocusingErr e (Zoomed m)
-
 ------------------------------------------------------------------------------
 -- Focusing
 ------------------------------------------------------------------------------
@@ -255,18 +222,6 @@ instance Applicative (k (Err e s)) => Applicative (FocusingErr e k s) where
   FocusingErr kf <*> FocusingErr ka = FocusingErr (kf <*> ka)
   {-# INLINE (<*>) #-}
 
-------------------------------------------------------------------------------
--- Magnified
-------------------------------------------------------------------------------
-
--- | This type family is used by 'Control.Lens.Zoom.Magnify' to describe the common effect type.
-type family Magnified (m :: * -> *) :: * -> * -> *
-type instance Magnified (ReaderT b m) = Effect m
-type instance Magnified ((->)b) = Const
-type instance Magnified (Strict.RWST a w s m) = EffectRWS w s m
-type instance Magnified (Lazy.RWST a w s m) = EffectRWS w s m
-type instance Magnified (IdentityT m) = Magnified m
-
 -----------------------------------------------------------------------------
 --- Effect
 -------------------------------------------------------------------------------

src/Control/Lens/Zoom.hs

@@ -29,8 +29,10 @@
 --
 -------------------------------------------------------------------------------
 module Control.Lens.Zoom
-  ( Magnify(..)
+  ( Magnified
+  , Magnify(..)
   , Zoom(..)
+  , Zoomed
   ) where
 
 import Control.Lens.Getter
@@ -71,6 +73,41 @@ import Prelude
 -- Chosen so that they have lower fixity than ('%='), and to match ('<~').
 infixr 2 `zoom`, `magnify`
 
+------------------------------------------------------------------------------
+-- Zoomed
+------------------------------------------------------------------------------
+
+-- | This type family is used by 'Control.Lens.Zoom.Zoom' to describe the common effect type.
+type family Zoomed (m :: * -> *) :: * -> * -> *
+type instance Zoomed (Strict.StateT s z) = Focusing z
+type instance Zoomed (Lazy.StateT s z) = Focusing z
+type instance Zoomed (ReaderT e m) = Zoomed m
+type instance Zoomed (IdentityT m) = Zoomed m
+type instance Zoomed (Strict.RWST r w s z) = FocusingWith w z
+type instance Zoomed (Lazy.RWST r w s z) = FocusingWith w z
+type instance Zoomed (Strict.WriterT w m) = FocusingPlus w (Zoomed m)
+type instance Zoomed (Lazy.WriterT w m) = FocusingPlus w (Zoomed m)
+type instance Zoomed (ListT m) = FocusingOn [] (Zoomed m)
+type instance Zoomed (MaybeT m) = FocusingMay (Zoomed m)
+type instance Zoomed (ErrorT e m) = FocusingErr e (Zoomed m)
+type instance Zoomed (ExceptT e m) = FocusingErr e (Zoomed m)
+
+------------------------------------------------------------------------------
+-- Magnified
+------------------------------------------------------------------------------
+
+-- | This type family is used by 'Control.Lens.Zoom.Magnify' to describe the common effect type.
+type family Magnified (m :: * -> *) :: * -> * -> *
+type instance Magnified (ReaderT b m) = Effect m
+type instance Magnified ((->)b) = Const
+type instance Magnified (Strict.RWST a w s m) = EffectRWS w s m
+type instance Magnified (Lazy.RWST a w s m) = EffectRWS w s m
+type instance Magnified (IdentityT m) = Magnified m
+
+------------------------------------------------------------------------------
+-- Zoom
+------------------------------------------------------------------------------
+
 -- | This class allows us to use 'zoom' in, changing the 'State' supplied by
 -- many different 'Control.Monad.Monad' transformers, potentially quite
 -- deep in a 'Monad' transformer stack.
@@ -161,6 +198,10 @@ instance Zoom m n s t => Zoom (ExceptT e m) (ExceptT e n) s t where
   zoom l = ExceptT . liftM getErr . zoom (\afb -> unfocusingErr #. l (FocusingErr #. afb)) . liftM Err . runExceptT
   {-# INLINE zoom #-}
 
+------------------------------------------------------------------------------
+-- Magnify
+------------------------------------------------------------------------------
+
 -- TODO: instance Zoom m m a a => Zoom (ContT r m) (ContT r m) a a where
 
 -- | This class allows us to use 'magnify' part of the environment, changing the environment supplied by