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

module Polysemy.ConstraintAbsorber.MonadError
  ( absorbError
  ) where

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


------------------------------------------------------------------------------
-- | Introduce a local 'S.MonadError' constraint on 'Sem' --- allowing it to
-- interop nicely with MTL.
--
-- @since 0.3.0.0
absorbError
    :: Member (Error e) r
    => (S.MonadError e (Sem r) => Sem r a)
       -- ^ A computation that requires an instance of 'S.MonadError' for
       -- 'Sem'. This might be something with type @'S.MonadError' e m => m a@.
    -> Sem r a
absorbError :: (MonadError e (Sem r) => Sem r a) -> Sem r a
absorbError = ErrorDict e (Sem r)
-> (forall s.
    Reifies s (ErrorDict e (Sem r)) :- MonadError e (Action (Sem r) s))
-> (MonadError e (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.MonadError _) @Action
  ((forall a. e -> Sem r a)
-> (forall a. Sem r a -> (e -> Sem r a) -> Sem r a)
-> ErrorDict e (Sem r)
forall k e (m :: k -> *).
(forall (a :: k). e -> m a)
-> (forall (a :: k). m a -> (e -> m a) -> m a) -> ErrorDict e m
ErrorDict forall a. e -> Sem r a
forall e (r :: EffectRow) a. Member (Error e) r => e -> Sem r a
throw forall a. Sem r a -> (e -> Sem r a) -> Sem r a
forall e (r :: EffectRow) a.
Member (Error e) r =>
Sem r a -> (e -> Sem r a) -> Sem r a
catch)
  ((Reifies s (ErrorDict e (Sem r)) =>
 Dict (MonadError e (Action (Sem r) s)))
-> Reifies s (ErrorDict e (Sem r))
   :- MonadError e (Action (Sem r) s)
forall (a :: Constraint) (b :: Constraint). (a => Dict b) -> a :- b
Sub Reifies s (ErrorDict e (Sem r)) =>
Dict (MonadError e (Action (Sem r) s))
forall (a :: Constraint). a => Dict a
Dict)
{-# INLINEABLE absorbError #-}


------------------------------------------------------------------------------
-- | A dictionary of the functions we need to supply
-- to make an instance of Error
data ErrorDict e m = ErrorDict
  { ErrorDict e m -> forall (a :: k). e -> m a
throwError_ :: forall a. e -> m a
  , ErrorDict e m -> forall (a :: k). m a -> (e -> m a) -> m a
catchError_ :: forall a. m a -> (e -> m a) -> 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 Error dictionary,
-- we can make an instance of @MonadError@ for the action
-- wrapped in @Action@.
instance ( Monad m
         , Reifies s' (ErrorDict e m)
         ) => S.MonadError e (Action m s') where
  throwError :: e -> Action m s' a
throwError e
e = 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
$ ErrorDict e m -> e -> m a
forall e k (m :: k -> *).
ErrorDict e m -> forall (a :: k). e -> m a
throwError_ (Proxy s' -> ErrorDict e m
forall k (s :: k) a (proxy :: k -> *). Reifies s a => proxy s -> a
reflect (Proxy s' -> ErrorDict e m) -> Proxy s' -> ErrorDict e m
forall a b. (a -> b) -> a -> b
$ Proxy s'
forall k (t :: k). Proxy t
Proxy @s') e
e
  {-# INLINEABLE throwError #-}
  catchError :: Action m s' a -> (e -> Action m s' a) -> Action m s' a
catchError Action m s' a
x e -> Action m s' a
f = 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
$ ErrorDict e m -> m a -> (e -> m a) -> m a
forall e k (m :: k -> *).
ErrorDict e m -> forall (a :: k). m a -> (e -> m a) -> m a
catchError_ (Proxy s' -> ErrorDict e m
forall k (s :: k) a (proxy :: k -> *). Reifies s a => proxy s -> a
reflect (Proxy s' -> ErrorDict e m) -> Proxy s' -> ErrorDict e 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) (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 -> m a) -> (e -> Action m s' a) -> e -> m a
forall b c a. (b -> c) -> (a -> b) -> a -> c
. e -> Action m s' a
f)
  {-# INLINEABLE catchError #-}