{-# LANGUAGE FlexibleInstances           #-}
{-# LANGUAGE GeneralizedNewtypeDeriving  #-}
{-# LANGUAGE MultiParamTypeClasses       #-}
{-# LANGUAGE UndecidableInstances        #-}

module Polysemy.ConstraintAbsorber.MonadWriter
  ( absorbWriter
  ) where

import qualified Control.Monad.Writer.Class as S
import           Polysemy
import           Polysemy.ConstraintAbsorber
import           Polysemy.Writer


------------------------------------------------------------------------------
-- | Introduce a local 'S.MonadWriter' constraint on 'Sem' --- allowing it to
-- interop nicely with MTL.
--
-- @since 0.3.0.0
absorbWriter
    :: forall w r a
     . ( Monoid w
       , Member (Writer w) r
       )
    => (S.MonadWriter w (Sem r) => Sem r a)
       -- ^ A computation that requires an instance of 'S.MonadWriter' for
       -- 'Sem'. This might be something with type @'S.MonadWriter' w m => m a@.
    -> Sem r a
absorbWriter :: (MonadWriter w (Sem r) => Sem r a) -> Sem r a
absorbWriter =
  let swapTuple :: (b, a) -> (a, b)
swapTuple (b
x,a
y) = (a
y,b
x)
      semTell :: w -> Sem r ()
semTell = w -> Sem r ()
forall o (r :: EffectRow). Member (Writer o) r => o -> Sem r ()
tell
      semListen :: Member (Writer w) r => Sem r b -> Sem r (b, w)
      semListen :: Sem r b -> Sem r (b, w)
semListen = ((w, b) -> (b, w)) -> Sem r (w, b) -> Sem r (b, w)
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap (w, b) -> (b, w)
forall b a. (b, a) -> (a, b)
swapTuple (Sem r (w, b) -> Sem r (b, w))
-> (Sem r b -> Sem r (w, b)) -> Sem r b -> Sem r (b, w)
forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall (r :: EffectRow) a.
Member (Writer w) r =>
Sem r a -> Sem r (w, a)
forall o (r :: EffectRow) a.
Member (Writer o) r =>
Sem r a -> Sem r (o, a)
listen @w
      semPass :: Member (Writer w) r => Sem r (b, w -> w) -> Sem r b
      semPass :: Sem r (b, w -> w) -> Sem r b
semPass = forall (r :: EffectRow) a.
Member (Writer w) r =>
Sem r (w -> w, a) -> Sem r a
forall o (r :: EffectRow) a.
Member (Writer o) r =>
Sem r (o -> o, a) -> Sem r a
pass @w (Sem r (w -> w, b) -> Sem r b)
-> (Sem r (b, w -> w) -> Sem r (w -> w, b))
-> Sem r (b, w -> w)
-> Sem r b
forall b c a. (b -> c) -> (a -> b) -> a -> c
. ((b, w -> w) -> (w -> w, b))
-> Sem r (b, w -> w) -> Sem r (w -> w, b)
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap (b, w -> w) -> (w -> w, b)
forall b a. (b, a) -> (a, b)
swapTuple
  in WriterDict w (Sem r)
-> (forall s.
    Reifies s (WriterDict w (Sem r))
    :- MonadWriter w (Action (Sem r) s))
-> (MonadWriter w (Sem r) => Sem r a)
-> Sem r a
forall (p :: (* -> *) -> Constraint) (x :: (* -> *) -> * -> * -> *)
       d (r :: EffectRow) a.
d
-> (forall s. Reifies s d :- p (x (Sem r) s))
-> (p (Sem r) => Sem r a)
-> Sem r a
absorbWithSem @(S.MonadWriter _) @Action
     ((w -> Sem r ())
-> (forall a. Sem r a -> Sem r (a, w))
-> (forall a. Sem r (a, w -> w) -> Sem r a)
-> WriterDict w (Sem r)
forall w (m :: * -> *).
(w -> m ())
-> (forall a. m a -> m (a, w))
-> (forall a. m (a, w -> w) -> m a)
-> WriterDict w m
WriterDict w -> Sem r ()
semTell forall b. Member (Writer w) r => Sem r b -> Sem r (b, w)
forall a. Sem r a -> Sem r (a, w)
semListen forall b. Member (Writer w) r => Sem r (b, w -> w) -> Sem r b
forall a. Sem r (a, w -> w) -> Sem r a
semPass)
     ((Reifies s (WriterDict w (Sem r)) =>
 Dict (MonadWriter w (Action (Sem r) s)))
-> Reifies s (WriterDict w (Sem r))
   :- MonadWriter w (Action (Sem r) s)
forall (a :: Constraint) (b :: Constraint). (a => Dict b) -> a :- b
Sub Reifies s (WriterDict w (Sem r)) =>
Dict (MonadWriter w (Action (Sem r) s))
forall (a :: Constraint). a => Dict a
Dict)
{-# INLINEABLE absorbWriter #-}


------------------------------------------------------------------------------
-- | A dictionary of the functions we need to supply
-- to make an instance of Writer
data WriterDict w m = WriterDict
  { WriterDict w m -> w -> m ()
tell_ :: w -> m ()
  , WriterDict w m -> forall a. m a -> m (a, w)
listen_ :: forall a. m a -> m (a, w)
  , WriterDict w m -> forall a. m (a, w -> w) -> m a
pass_ :: forall a. m (a, w -> w) -> m a
  }


------------------------------------------------------------------------------
-- | Wrapper for a monadic action with phantom
-- type parameter for reflection.
-- Locally defined so that the instance we are going
-- to build with reflection must be coherent, that is
-- there cannot be orphans.
newtype Action m s' a = Action { Action m s' a -> m a
action :: m a }
  deriving (a -> Action m s' b -> Action m s' a
(a -> b) -> Action m s' a -> Action m s' b
(forall a b. (a -> b) -> Action m s' a -> Action m s' b)
-> (forall a b. a -> Action m s' b -> Action m s' a)
-> Functor (Action m s')
forall a b. a -> Action m s' b -> Action m s' a
forall a b. (a -> b) -> Action m s' a -> Action m s' b
forall (f :: * -> *).
(forall a b. (a -> b) -> f a -> f b)
-> (forall a b. a -> f b -> f a) -> Functor f
forall (m :: * -> *) k (s' :: k) a b.
Functor m =>
a -> Action m s' b -> Action m s' a
forall (m :: * -> *) k (s' :: k) a b.
Functor m =>
(a -> b) -> Action m s' a -> Action m s' b
<$ :: a -> Action m s' b -> Action m s' a
$c<$ :: forall (m :: * -> *) k (s' :: k) a b.
Functor m =>
a -> Action m s' b -> Action m s' a
fmap :: (a -> b) -> Action m s' a -> Action m s' b
$cfmap :: forall (m :: * -> *) k (s' :: k) a b.
Functor m =>
(a -> b) -> Action m s' a -> Action m s' b
Functor, Functor (Action m s')
a -> Action m s' a
Functor (Action m s')
-> (forall a. a -> Action m s' a)
-> (forall a b.
    Action m s' (a -> b) -> Action m s' a -> Action m s' b)
-> (forall a b c.
    (a -> b -> c) -> Action m s' a -> Action m s' b -> Action m s' c)
-> (forall a b. Action m s' a -> Action m s' b -> Action m s' b)
-> (forall a b. Action m s' a -> Action m s' b -> Action m s' a)
-> Applicative (Action m s')
Action m s' a -> Action m s' b -> Action m s' b
Action m s' a -> Action m s' b -> Action m s' a
Action m s' (a -> b) -> Action m s' a -> Action m s' b
(a -> b -> c) -> Action m s' a -> Action m s' b -> Action m s' c
forall a. a -> Action m s' a
forall a b. Action m s' a -> Action m s' b -> Action m s' a
forall a b. Action m s' a -> Action m s' b -> Action m s' b
forall a b. Action m s' (a -> b) -> Action m s' a -> Action m s' b
forall a b c.
(a -> b -> c) -> Action m s' a -> Action m s' b -> Action m s' c
forall (f :: * -> *).
Functor f
-> (forall a. a -> f a)
-> (forall a b. f (a -> b) -> f a -> f b)
-> (forall a b c. (a -> b -> c) -> f a -> f b -> f c)
-> (forall a b. f a -> f b -> f b)
-> (forall a b. f a -> f b -> f a)
-> Applicative f
forall (m :: * -> *) k (s' :: k).
Applicative m =>
Functor (Action m s')
forall (m :: * -> *) k (s' :: k) a.
Applicative m =>
a -> Action m s' a
forall (m :: * -> *) k (s' :: k) a b.
Applicative m =>
Action m s' a -> Action m s' b -> Action m s' a
forall (m :: * -> *) k (s' :: k) a b.
Applicative m =>
Action m s' a -> Action m s' b -> Action m s' b
forall (m :: * -> *) k (s' :: k) a b.
Applicative m =>
Action m s' (a -> b) -> Action m s' a -> Action m s' b
forall (m :: * -> *) k (s' :: k) a b c.
Applicative m =>
(a -> b -> c) -> Action m s' a -> Action m s' b -> Action m s' c
<* :: Action m s' a -> Action m s' b -> Action m s' a
$c<* :: forall (m :: * -> *) k (s' :: k) a b.
Applicative m =>
Action m s' a -> Action m s' b -> Action m s' a
*> :: Action m s' a -> Action m s' b -> Action m s' b
$c*> :: forall (m :: * -> *) k (s' :: k) a b.
Applicative m =>
Action m s' a -> Action m s' b -> Action m s' b
liftA2 :: (a -> b -> c) -> Action m s' a -> Action m s' b -> Action m s' c
$cliftA2 :: forall (m :: * -> *) k (s' :: k) a b c.
Applicative m =>
(a -> b -> c) -> Action m s' a -> Action m s' b -> Action m s' c
<*> :: Action m s' (a -> b) -> Action m s' a -> Action m s' b
$c<*> :: forall (m :: * -> *) k (s' :: k) a b.
Applicative m =>
Action m s' (a -> b) -> Action m s' a -> Action m s' b
pure :: a -> Action m s' a
$cpure :: forall (m :: * -> *) k (s' :: k) a.
Applicative m =>
a -> Action m s' a
$cp1Applicative :: forall (m :: * -> *) k (s' :: k).
Applicative m =>
Functor (Action m s')
Applicative, Applicative (Action m s')
a -> Action m s' a
Applicative (Action m s')
-> (forall a b.
    Action m s' a -> (a -> Action m s' b) -> Action m s' b)
-> (forall a b. Action m s' a -> Action m s' b -> Action m s' b)
-> (forall a. a -> Action m s' a)
-> Monad (Action m s')
Action m s' a -> (a -> Action m s' b) -> Action m s' b
Action m s' a -> Action m s' b -> Action m s' b
forall a. a -> Action m s' a
forall a b. Action m s' a -> Action m s' b -> Action m s' b
forall a b. Action m s' a -> (a -> Action m s' b) -> Action m s' b
forall (m :: * -> *).
Applicative m
-> (forall a b. m a -> (a -> m b) -> m b)
-> (forall a b. m a -> m b -> m b)
-> (forall a. a -> m a)
-> Monad m
forall (m :: * -> *) k (s' :: k).
Monad m =>
Applicative (Action m s')
forall (m :: * -> *) k (s' :: k) a. Monad m => a -> Action m s' a
forall (m :: * -> *) k (s' :: k) a b.
Monad m =>
Action m s' a -> Action m s' b -> Action m s' b
forall (m :: * -> *) k (s' :: k) a b.
Monad m =>
Action m s' a -> (a -> Action m s' b) -> Action m s' b
return :: a -> Action m s' a
$creturn :: forall (m :: * -> *) k (s' :: k) a. Monad m => a -> Action m s' a
>> :: Action m s' a -> Action m s' b -> Action m s' b
$c>> :: forall (m :: * -> *) k (s' :: k) a b.
Monad m =>
Action m s' a -> Action m s' b -> Action m s' b
>>= :: Action m s' a -> (a -> Action m s' b) -> Action m s' b
$c>>= :: forall (m :: * -> *) k (s' :: k) a b.
Monad m =>
Action m s' a -> (a -> Action m s' b) -> Action m s' b
$cp1Monad :: forall (m :: * -> *) k (s' :: k).
Monad m =>
Applicative (Action m s')
Monad)


------------------------------------------------------------------------------
-- | Given a reifiable mtl Writer dictionary,
-- we can make an instance of @MonadWriter@ for the action
-- wrapped in @Action@.
instance ( Monad m
         , Monoid w
         , Reifies s' (WriterDict w m)
         ) => S.MonadWriter w (Action m s') where
  tell :: w -> Action m s' ()
tell w
w = m () -> Action m s' ()
forall k k (m :: k -> *) (s' :: k) (a :: k). m a -> Action m s' a
Action (m () -> Action m s' ()) -> m () -> Action m s' ()
forall a b. (a -> b) -> a -> b
$ WriterDict w m -> w -> m ()
forall w (m :: * -> *). WriterDict w m -> w -> m ()
tell_ (Proxy s' -> WriterDict w m
forall k (s :: k) a (proxy :: k -> *). Reifies s a => proxy s -> a
reflect (Proxy s' -> WriterDict w m) -> Proxy s' -> WriterDict w m
forall a b. (a -> b) -> a -> b
$ Proxy s'
forall k (t :: k). Proxy t
Proxy @s') w
w
  {-# INLINEABLE tell #-}
  listen :: Action m s' a -> Action m s' (a, w)
listen Action m s' a
x = m (a, w) -> Action m s' (a, w)
forall k k (m :: k -> *) (s' :: k) (a :: k). m a -> Action m s' a
Action (m (a, w) -> Action m s' (a, w)) -> m (a, w) -> Action m s' (a, w)
forall a b. (a -> b) -> a -> b
$ WriterDict w m -> m a -> m (a, w)
forall w (m :: * -> *). WriterDict w m -> forall a. m a -> m (a, w)
listen_ (Proxy s' -> WriterDict w m
forall k (s :: k) a (proxy :: k -> *). Reifies s a => proxy s -> a
reflect (Proxy s' -> WriterDict w m) -> Proxy s' -> WriterDict w m
forall a b. (a -> b) -> a -> b
$ Proxy s'
forall k (t :: k). Proxy t
Proxy @s') (Action m s' a -> m a
forall k (m :: k -> *) k (s' :: k) (a :: k). Action m s' a -> m a
action Action m s' a
x)
  {-# INLINEABLE listen #-}
  pass :: Action m s' (a, w -> w) -> Action m s' a
pass Action m s' (a, w -> w)
x = m a -> Action m s' a
forall k k (m :: k -> *) (s' :: k) (a :: k). m a -> Action m s' a
Action (m a -> Action m s' a) -> m a -> Action m s' a
forall a b. (a -> b) -> a -> b
$ WriterDict w m -> m (a, w -> w) -> m a
forall w (m :: * -> *).
WriterDict w m -> forall a. m (a, w -> w) -> m a
pass_ (Proxy s' -> WriterDict w m
forall k (s :: k) a (proxy :: k -> *). Reifies s a => proxy s -> a
reflect (Proxy s' -> WriterDict w m) -> Proxy s' -> WriterDict w m
forall a b. (a -> b) -> a -> b
$ Proxy s'
forall k (t :: k). Proxy t
Proxy @s') (Action m s' (a, w -> w) -> m (a, w -> w)
forall k (m :: k -> *) k (s' :: k) (a :: k). Action m s' a -> m a
action Action m s' (a, w -> w)
x)
  {-# INLINEABLE pass #-}