{-# LANGUAGE CPP #-}
#if __GLASGOW_HASKELL__ >= 702
{-# LANGUAGE Safe #-}
#endif
#if __GLASGOW_HASKELL__ >= 710
{-# LANGUAGE AutoDeriveTypeable #-}
#endif
#if !(MIN_VERSION_base(4,9,0))
{-# OPTIONS_GHC -fno-warn-orphans #-}
#endif
module Control.Monad.Trans.Error
{-# DEPRECATED "Use Control.Monad.Trans.Except instead" #-} (
Error(..),
ErrorList(..),
ErrorT(..),
mapErrorT,
throwError,
catchError,
liftCallCC,
liftListen,
liftPass,
) where
import Control.Monad.IO.Class
import Control.Monad.Signatures
import Control.Monad.Trans.Class
import Data.Functor.Classes
#if MIN_VERSION_base(4,12,0)
import Data.Functor.Contravariant
#endif
import Control.Applicative
import Control.Exception (IOException)
import Control.Monad
#if MIN_VERSION_base(4,9,0)
import qualified Control.Monad.Fail as Fail
#endif
import Control.Monad.Fix
#if !(MIN_VERSION_base(4,6,0))
import Control.Monad.Instances ()
#endif
import Data.Foldable (Foldable(foldMap))
import Data.Monoid (mempty)
import Data.Traversable (Traversable(traverse))
import System.IO.Error
#if !(MIN_VERSION_base(4,9,0))
instance MonadPlus IO where
mzero = ioError (userError "mzero")
m `mplus` n = m `catchIOError` \ _ -> n
instance Alternative IO where
empty = mzero
(<|>) = mplus
# if !(MIN_VERSION_base(4,4,0))
catchIOError :: IO a -> (IOError -> IO a) -> IO a
catchIOError = catch
# endif
#endif
instance (Error e) => Alternative (Either e) where
empty :: forall a. Either e a
empty = forall a b. a -> Either a b
Left forall a. Error a => a
noMsg
Left e
_ <|> :: forall a. Either e a -> Either e a -> Either e a
<|> Either e a
n = Either e a
n
Either e a
m <|> Either e a
_ = Either e a
m
instance (Error e) => MonadPlus (Either e) where
mzero :: forall a. Either e a
mzero = forall a b. a -> Either a b
Left forall a. Error a => a
noMsg
Left e
_ mplus :: forall a. Either e a -> Either e a -> Either e a
`mplus` Either e a
n = Either e a
n
Either e a
m `mplus` Either e a
_ = Either e a
m
#if !(MIN_VERSION_base(4,3,0))
instance Applicative (Either e) where
pure = Right
Left e <*> _ = Left e
Right f <*> r = fmap f r
instance Monad (Either e) where
return = Right
Left l >>= _ = Left l
Right r >>= k = k r
instance MonadFix (Either e) where
mfix f = let
a = f $ case a of
Right r -> r
_ -> error "empty mfix argument"
in a
#endif /* base to 4.2.0.x */
class Error a where
noMsg :: a
strMsg :: String -> a
noMsg = forall a. Error a => String -> a
strMsg String
""
strMsg String
_ = forall a. Error a => a
noMsg
instance Error IOException where
strMsg :: String -> IOException
strMsg = String -> IOException
userError
instance (ErrorList a) => Error [a] where
strMsg :: String -> [a]
strMsg = forall a. ErrorList a => String -> [a]
listMsg
class ErrorList a where
listMsg :: String -> [a]
instance ErrorList Char where
listMsg :: String -> String
listMsg = forall a. a -> a
id
newtype ErrorT e m a = ErrorT { forall e (m :: * -> *) a. ErrorT e m a -> m (Either e a)
runErrorT :: m (Either e a) }
instance (Eq e, Eq1 m) => Eq1 (ErrorT e m) where
liftEq :: forall a b.
(a -> b -> Bool) -> ErrorT e m a -> ErrorT e m b -> Bool
liftEq a -> b -> Bool
eq (ErrorT m (Either e a)
x) (ErrorT m (Either e b)
y) = forall (f :: * -> *) a b.
Eq1 f =>
(a -> b -> Bool) -> f a -> f b -> Bool
liftEq (forall (f :: * -> *) a b.
Eq1 f =>
(a -> b -> Bool) -> f a -> f b -> Bool
liftEq a -> b -> Bool
eq) m (Either e a)
x m (Either e b)
y
instance (Ord e, Ord1 m) => Ord1 (ErrorT e m) where
liftCompare :: forall a b.
(a -> b -> Ordering) -> ErrorT e m a -> ErrorT e m b -> Ordering
liftCompare a -> b -> Ordering
comp (ErrorT m (Either e a)
x) (ErrorT m (Either e b)
y) = forall (f :: * -> *) a b.
Ord1 f =>
(a -> b -> Ordering) -> f a -> f b -> Ordering
liftCompare (forall (f :: * -> *) a b.
Ord1 f =>
(a -> b -> Ordering) -> f a -> f b -> Ordering
liftCompare a -> b -> Ordering
comp) m (Either e a)
x m (Either e b)
y
instance (Read e, Read1 m) => Read1 (ErrorT e m) where
liftReadsPrec :: forall a.
(Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (ErrorT e m a)
liftReadsPrec Int -> ReadS a
rp ReadS [a]
rl = forall a. (String -> ReadS a) -> Int -> ReadS a
readsData forall a b. (a -> b) -> a -> b
$
forall a t.
(Int -> ReadS a) -> String -> (a -> t) -> String -> ReadS t
readsUnaryWith (forall (f :: * -> *) a.
Read1 f =>
(Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (f a)
liftReadsPrec Int -> ReadS (Either e a)
rp' ReadS [Either e a]
rl') String
"ErrorT" forall e (m :: * -> *) a. m (Either e a) -> ErrorT e m a
ErrorT
where
rp' :: Int -> ReadS (Either e a)
rp' = forall (f :: * -> *) a.
Read1 f =>
(Int -> ReadS a) -> ReadS [a] -> Int -> ReadS (f a)
liftReadsPrec Int -> ReadS a
rp ReadS [a]
rl
rl' :: ReadS [Either e a]
rl' = forall (f :: * -> *) a.
Read1 f =>
(Int -> ReadS a) -> ReadS [a] -> ReadS [f a]
liftReadList Int -> ReadS a
rp ReadS [a]
rl
instance (Show e, Show1 m) => Show1 (ErrorT e m) where
liftShowsPrec :: forall a.
(Int -> a -> String -> String)
-> ([a] -> String -> String)
-> Int
-> ErrorT e m a
-> String
-> String
liftShowsPrec Int -> a -> String -> String
sp [a] -> String -> String
sl Int
d (ErrorT m (Either e a)
m) =
forall a.
(Int -> a -> String -> String)
-> String -> Int -> a -> String -> String
showsUnaryWith (forall (f :: * -> *) a.
Show1 f =>
(Int -> a -> String -> String)
-> ([a] -> String -> String) -> Int -> f a -> String -> String
liftShowsPrec Int -> Either e a -> String -> String
sp' [Either e a] -> String -> String
sl') String
"ErrorT" Int
d m (Either e a)
m
where
sp' :: Int -> Either e a -> String -> String
sp' = forall (f :: * -> *) a.
Show1 f =>
(Int -> a -> String -> String)
-> ([a] -> String -> String) -> Int -> f a -> String -> String
liftShowsPrec Int -> a -> String -> String
sp [a] -> String -> String
sl
sl' :: [Either e a] -> String -> String
sl' = forall (f :: * -> *) a.
Show1 f =>
(Int -> a -> String -> String)
-> ([a] -> String -> String) -> [f a] -> String -> String
liftShowList Int -> a -> String -> String
sp [a] -> String -> String
sl
instance (Eq e, Eq1 m, Eq a) => Eq (ErrorT e m a) where == :: ErrorT e m a -> ErrorT e m a -> Bool
(==) = forall (f :: * -> *) a. (Eq1 f, Eq a) => f a -> f a -> Bool
eq1
instance (Ord e, Ord1 m, Ord a) => Ord (ErrorT e m a) where compare :: ErrorT e m a -> ErrorT e m a -> Ordering
compare = forall (f :: * -> *) a. (Ord1 f, Ord a) => f a -> f a -> Ordering
compare1
instance (Read e, Read1 m, Read a) => Read (ErrorT e m a) where
readsPrec :: Int -> ReadS (ErrorT e m a)
readsPrec = forall (f :: * -> *) a. (Read1 f, Read a) => Int -> ReadS (f a)
readsPrec1
instance (Show e, Show1 m, Show a) => Show (ErrorT e m a) where
showsPrec :: Int -> ErrorT e m a -> String -> String
showsPrec = forall (f :: * -> *) a.
(Show1 f, Show a) =>
Int -> f a -> String -> String
showsPrec1
mapErrorT :: (m (Either e a) -> n (Either e' b))
-> ErrorT e m a
-> ErrorT e' n b
mapErrorT :: forall (m :: * -> *) e a (n :: * -> *) e' b.
(m (Either e a) -> n (Either e' b))
-> ErrorT e m a -> ErrorT e' n b
mapErrorT m (Either e a) -> n (Either e' b)
f ErrorT e m a
m = forall e (m :: * -> *) a. m (Either e a) -> ErrorT e m a
ErrorT forall a b. (a -> b) -> a -> b
$ m (Either e a) -> n (Either e' b)
f (forall e (m :: * -> *) a. ErrorT e m a -> m (Either e a)
runErrorT ErrorT e m a
m)
instance (Functor m) => Functor (ErrorT e m) where
fmap :: forall a b. (a -> b) -> ErrorT e m a -> ErrorT e m b
fmap a -> b
f = forall e (m :: * -> *) a. m (Either e a) -> ErrorT e m a
ErrorT forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap (forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap a -> b
f) forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall e (m :: * -> *) a. ErrorT e m a -> m (Either e a)
runErrorT
instance (Foldable f) => Foldable (ErrorT e f) where
foldMap :: forall m a. Monoid m => (a -> m) -> ErrorT e f a -> m
foldMap a -> m
f (ErrorT f (Either e a)
a) = forall (t :: * -> *) m a.
(Foldable t, Monoid m) =>
(a -> m) -> t a -> m
foldMap (forall a c b. (a -> c) -> (b -> c) -> Either a b -> c
either (forall a b. a -> b -> a
const forall a. Monoid a => a
mempty) a -> m
f) f (Either e a)
a
instance (Traversable f) => Traversable (ErrorT e f) where
traverse :: forall (f :: * -> *) a b.
Applicative f =>
(a -> f b) -> ErrorT e f a -> f (ErrorT e f b)
traverse a -> f b
f (ErrorT f (Either e a)
a) =
forall e (m :: * -> *) a. m (Either e a) -> ErrorT e m a
ErrorT forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> forall (t :: * -> *) (f :: * -> *) a b.
(Traversable t, Applicative f) =>
(a -> f b) -> t a -> f (t b)
traverse (forall a c b. (a -> c) -> (b -> c) -> Either a b -> c
either (forall (f :: * -> *) a. Applicative f => a -> f a
pure forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a b. a -> Either a b
Left) (forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap forall a b. b -> Either a b
Right forall b c a. (b -> c) -> (a -> b) -> a -> c
. a -> f b
f)) f (Either e a)
a
instance (Functor m, Monad m) => Applicative (ErrorT e m) where
pure :: forall a. a -> ErrorT e m a
pure a
a = forall e (m :: * -> *) a. m (Either e a) -> ErrorT e m a
ErrorT forall a b. (a -> b) -> a -> b
$ forall (m :: * -> *) a. Monad m => a -> m a
return (forall a b. b -> Either a b
Right a
a)
ErrorT e m (a -> b)
f <*> :: forall a b. ErrorT e m (a -> b) -> ErrorT e m a -> ErrorT e m b
<*> ErrorT e m a
v = forall e (m :: * -> *) a. m (Either e a) -> ErrorT e m a
ErrorT forall a b. (a -> b) -> a -> b
$ do
Either e (a -> b)
mf <- forall e (m :: * -> *) a. ErrorT e m a -> m (Either e a)
runErrorT ErrorT e m (a -> b)
f
case Either e (a -> b)
mf of
Left e
e -> forall (m :: * -> *) a. Monad m => a -> m a
return (forall a b. a -> Either a b
Left e
e)
Right a -> b
k -> do
Either e a
mv <- forall e (m :: * -> *) a. ErrorT e m a -> m (Either e a)
runErrorT ErrorT e m a
v
case Either e a
mv of
Left e
e -> forall (m :: * -> *) a. Monad m => a -> m a
return (forall a b. a -> Either a b
Left e
e)
Right a
x -> forall (m :: * -> *) a. Monad m => a -> m a
return (forall a b. b -> Either a b
Right (a -> b
k a
x))
instance (Functor m, Monad m, Error e) => Alternative (ErrorT e m) where
empty :: forall a. ErrorT e m a
empty = forall (m :: * -> *) a. MonadPlus m => m a
mzero
<|> :: forall a. ErrorT e m a -> ErrorT e m a -> ErrorT e m a
(<|>) = forall (m :: * -> *) a. MonadPlus m => m a -> m a -> m a
mplus
instance (Monad m, Error e) => Monad (ErrorT e m) where
#if !(MIN_VERSION_base(4,8,0))
return a = ErrorT $ return (Right a)
#endif
ErrorT e m a
m >>= :: forall a b. ErrorT e m a -> (a -> ErrorT e m b) -> ErrorT e m b
>>= a -> ErrorT e m b
k = forall e (m :: * -> *) a. m (Either e a) -> ErrorT e m a
ErrorT forall a b. (a -> b) -> a -> b
$ do
Either e a
a <- forall e (m :: * -> *) a. ErrorT e m a -> m (Either e a)
runErrorT ErrorT e m a
m
case Either e a
a of
Left e
l -> forall (m :: * -> *) a. Monad m => a -> m a
return (forall a b. a -> Either a b
Left e
l)
Right a
r -> forall e (m :: * -> *) a. ErrorT e m a -> m (Either e a)
runErrorT (a -> ErrorT e m b
k a
r)
#if !(MIN_VERSION_base(4,13,0))
fail msg = ErrorT $ return (Left (strMsg msg))
#endif
#if MIN_VERSION_base(4,9,0)
instance (Monad m, Error e) => Fail.MonadFail (ErrorT e m) where
fail :: forall a. String -> ErrorT e m a
fail String
msg = forall e (m :: * -> *) a. m (Either e a) -> ErrorT e m a
ErrorT forall a b. (a -> b) -> a -> b
$ forall (m :: * -> *) a. Monad m => a -> m a
return (forall a b. a -> Either a b
Left (forall a. Error a => String -> a
strMsg String
msg))
#endif
instance (Monad m, Error e) => MonadPlus (ErrorT e m) where
mzero :: forall a. ErrorT e m a
mzero = forall e (m :: * -> *) a. m (Either e a) -> ErrorT e m a
ErrorT forall a b. (a -> b) -> a -> b
$ forall (m :: * -> *) a. Monad m => a -> m a
return (forall a b. a -> Either a b
Left forall a. Error a => a
noMsg)
ErrorT e m a
m mplus :: forall a. ErrorT e m a -> ErrorT e m a -> ErrorT e m a
`mplus` ErrorT e m a
n = forall e (m :: * -> *) a. m (Either e a) -> ErrorT e m a
ErrorT forall a b. (a -> b) -> a -> b
$ do
Either e a
a <- forall e (m :: * -> *) a. ErrorT e m a -> m (Either e a)
runErrorT ErrorT e m a
m
case Either e a
a of
Left e
_ -> forall e (m :: * -> *) a. ErrorT e m a -> m (Either e a)
runErrorT ErrorT e m a
n
Right a
r -> forall (m :: * -> *) a. Monad m => a -> m a
return (forall a b. b -> Either a b
Right a
r)
instance (MonadFix m, Error e) => MonadFix (ErrorT e m) where
mfix :: forall a. (a -> ErrorT e m a) -> ErrorT e m a
mfix a -> ErrorT e m a
f = forall e (m :: * -> *) a. m (Either e a) -> ErrorT e m a
ErrorT forall a b. (a -> b) -> a -> b
$ forall (m :: * -> *) a. MonadFix m => (a -> m a) -> m a
mfix forall a b. (a -> b) -> a -> b
$ \ Either e a
a -> forall e (m :: * -> *) a. ErrorT e m a -> m (Either e a)
runErrorT forall a b. (a -> b) -> a -> b
$ a -> ErrorT e m a
f forall a b. (a -> b) -> a -> b
$ case Either e a
a of
Right a
r -> a
r
Either e a
_ -> forall a. HasCallStack => String -> a
error String
"empty mfix argument"
instance MonadTrans (ErrorT e) where
lift :: forall (m :: * -> *) a. Monad m => m a -> ErrorT e m a
lift m a
m = forall e (m :: * -> *) a. m (Either e a) -> ErrorT e m a
ErrorT forall a b. (a -> b) -> a -> b
$ do
a
a <- m a
m
forall (m :: * -> *) a. Monad m => a -> m a
return (forall a b. b -> Either a b
Right a
a)
instance (Error e, MonadIO m) => MonadIO (ErrorT e m) where
liftIO :: forall a. IO a -> ErrorT e m a
liftIO = forall (t :: (* -> *) -> * -> *) (m :: * -> *) a.
(MonadTrans t, Monad m) =>
m a -> t m a
lift forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall (m :: * -> *) a. MonadIO m => IO a -> m a
liftIO
#if MIN_VERSION_base(4,12,0)
instance Contravariant m => Contravariant (ErrorT e m) where
contramap :: forall a' a. (a' -> a) -> ErrorT e m a -> ErrorT e m a'
contramap a' -> a
f = forall e (m :: * -> *) a. m (Either e a) -> ErrorT e m a
ErrorT forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall (f :: * -> *) a' a.
Contravariant f =>
(a' -> a) -> f a -> f a'
contramap (forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap a' -> a
f) forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall e (m :: * -> *) a. ErrorT e m a -> m (Either e a)
runErrorT
#endif
throwError :: (Monad m) => e -> ErrorT e m a
throwError :: forall (m :: * -> *) e a. Monad m => e -> ErrorT e m a
throwError e
l = forall e (m :: * -> *) a. m (Either e a) -> ErrorT e m a
ErrorT forall a b. (a -> b) -> a -> b
$ forall (m :: * -> *) a. Monad m => a -> m a
return (forall a b. a -> Either a b
Left e
l)
catchError :: (Monad m) =>
ErrorT e m a
-> (e -> ErrorT e m a)
-> ErrorT e m a
ErrorT e m a
m catchError :: forall (m :: * -> *) e a.
Monad m =>
ErrorT e m a -> (e -> ErrorT e m a) -> ErrorT e m a
`catchError` e -> ErrorT e m a
h = forall e (m :: * -> *) a. m (Either e a) -> ErrorT e m a
ErrorT forall a b. (a -> b) -> a -> b
$ do
Either e a
a <- forall e (m :: * -> *) a. ErrorT e m a -> m (Either e a)
runErrorT ErrorT e m a
m
case Either e a
a of
Left e
l -> forall e (m :: * -> *) a. ErrorT e m a -> m (Either e a)
runErrorT (e -> ErrorT e m a
h e
l)
Right a
r -> forall (m :: * -> *) a. Monad m => a -> m a
return (forall a b. b -> Either a b
Right a
r)
liftCallCC :: CallCC m (Either e a) (Either e b) -> CallCC (ErrorT e m) a b
liftCallCC :: forall (m :: * -> *) e a b.
CallCC m (Either e a) (Either e b) -> CallCC (ErrorT e m) a b
liftCallCC CallCC m (Either e a) (Either e b)
callCC (a -> ErrorT e m b) -> ErrorT e m a
f = forall e (m :: * -> *) a. m (Either e a) -> ErrorT e m a
ErrorT forall a b. (a -> b) -> a -> b
$
CallCC m (Either e a) (Either e b)
callCC forall a b. (a -> b) -> a -> b
$ \ Either e a -> m (Either e b)
c ->
forall e (m :: * -> *) a. ErrorT e m a -> m (Either e a)
runErrorT ((a -> ErrorT e m b) -> ErrorT e m a
f (\ a
a -> forall e (m :: * -> *) a. m (Either e a) -> ErrorT e m a
ErrorT forall a b. (a -> b) -> a -> b
$ Either e a -> m (Either e b)
c (forall a b. b -> Either a b
Right a
a)))
liftListen :: (Monad m) => Listen w m (Either e a) -> Listen w (ErrorT e m) a
liftListen :: forall (m :: * -> *) w e a.
Monad m =>
Listen w m (Either e a) -> Listen w (ErrorT e m) a
liftListen Listen w m (Either e a)
listen = forall (m :: * -> *) e a (n :: * -> *) e' b.
(m (Either e a) -> n (Either e' b))
-> ErrorT e m a -> ErrorT e' n b
mapErrorT forall a b. (a -> b) -> a -> b
$ \ m (Either e a)
m -> do
(Either e a
a, w
w) <- Listen w m (Either e a)
listen m (Either e a)
m
forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$! forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap (\ a
r -> (a
r, w
w)) Either e a
a
liftPass :: (Monad m) => Pass w m (Either e a) -> Pass w (ErrorT e m) a
liftPass :: forall (m :: * -> *) w e a.
Monad m =>
Pass w m (Either e a) -> Pass w (ErrorT e m) a
liftPass Pass w m (Either e a)
pass = forall (m :: * -> *) e a (n :: * -> *) e' b.
(m (Either e a) -> n (Either e' b))
-> ErrorT e m a -> ErrorT e' n b
mapErrorT forall a b. (a -> b) -> a -> b
$ \ m (Either e (a, w -> w))
m -> Pass w m (Either e a)
pass forall a b. (a -> b) -> a -> b
$ do
Either e (a, w -> w)
a <- m (Either e (a, w -> w))
m
forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$! case Either e (a, w -> w)
a of
Left e
l -> (forall a b. a -> Either a b
Left e
l, forall a. a -> a
id)
Right (a
r, w -> w
f) -> (forall a b. b -> Either a b
Right a
r, w -> w
f)