-----------------------------------------------------------------------------
-- |
-- Module      :  System.Error
-- Copyright   :  (c) 2020-2021 EMQ Technologies Co., Ltd.
-- License     :  BSD-style (see the LICENSE file)
--
-- Maintainer  :  Feng Lee, feng@emqx.io
--                Yang M, yangm@emqx.io
-- Stability   :  experimental
-- Portability :  portable
--
-- Handle the system Error/Exception.
--
-----------------------------------------------------------------------------
module System.Error where

import Control.Monad (IO, pure)
import Data.Functor (map)
import Data.Either (Either(..))
import Data.Show (class Show)
import Data.Void (Void)
import Data.Function (const)

-- IO Exception
foreign import data Error :: Type

instance Show Error where
  show = showErrorImpl

foreign import showErrorImpl :: Error -> String

-- erlang:raise(Class, Reason, Stacktrace) -> no_return()

throw :: forall e. e -> IO Void
throw s = throwException s

try :: forall a e. IO a -> IO (Either e a)
try action = catchException (map Right action) (\e -> pure (Left e))

catch :: forall a e. IO a -> (e -> IO a) -> IO a
catch = catchException
{-
foreign import error :: String -> Error

foreign import message :: Error -> String

foreign import name :: Error -> String
-}

foreign import throwException :: forall e. e -> IO Void

foreign import catchException :: forall a e. IO a -> (e -> IO a) -> IO a

foreign import bracket :: forall a b c. IO a -> (a -> IO b) -> (a -> IO c) -> IO c

bracket_ :: forall a b c. IO a -> IO b -> IO c -> IO c
bracket_ before end thing = bracket before (const end) (const thing)

foreign import bracketOnError :: forall a b c. IO a -> (a -> IO b) -> (a -> IO c) -> IO c

foreign import finally :: forall a b. IO a -> IO b -> IO a
foreign import onException :: forall a b. IO a -> IO b -> IO a