#endif
) where
-import {-# SOURCE #-} Prelude (catch)
+#ifndef __HUGS__
+import qualified Control.Exception.Base as New (catch)
+#endif
+#ifndef __HUGS__
import Data.Either
+#endif
import Data.Maybe
#ifdef __GLASGOW_HASKELL__
#endif
#ifdef __HUGS__
-import Hugs.Prelude(Handle, IOException(..), IOErrorType(..))
+import Hugs.Prelude(Handle, IOException(..), IOErrorType(..), IO)
#endif
#ifdef __NHC__
-import Prelude
import IO
( IOError ()
, try
IOError{ ioe_type = t,
ioe_location = location,
ioe_description = "",
+#if defined(__GLASGOW_HASKELL__)
+ ioe_errno = Nothing,
+#endif
ioe_handle = maybe_hdl,
ioe_filename = maybe_filename
}
-> Maybe Handle
-> Maybe FilePath
-> IOError
-annotateIOError (IOError ohdl errTy _ str opath) loc hdl path =
- IOError (hdl `mplus` ohdl) errTy loc str (path `mplus` opath)
+annotateIOError ioe loc hdl path =
+ ioe{ ioe_handle = hdl `mplus` ioe_handle ioe,
+ ioe_location = loc, ioe_filename = path `mplus` ioe_filename ioe }
where
Nothing `mplus` ys = ys
xs `mplus` _ = xs
annotateIOError (PatternError loc) msg' file' hdl' =
PatternError (loc++'\n':msg')
#endif
+
+#ifndef __HUGS__
+-- | The 'catch' function establishes a handler that receives any 'IOError'
+-- raised in the action protected by 'catch'. An 'IOError' is caught by
+-- the most recent handler established by 'catch'. These handlers are
+-- not selective: all 'IOError's are caught. Exception propagation
+-- must be explicitly provided in a handler by re-raising any unwanted
+-- exceptions. For example, in
+--
+-- > f = catch g (\e -> if IO.isEOFError e then return [] else ioError e)
+--
+-- the function @f@ returns @[]@ when an end-of-file exception
+-- (cf. 'System.IO.Error.isEOFError') occurs in @g@; otherwise, the
+-- exception is propagated to the next outer handler.
+--
+-- When an exception propagates outside the main program, the Haskell
+-- system prints the associated 'IOError' value and exits the program.
+--
+-- Non-I\/O exceptions are not caught by this variant; to catch all
+-- exceptions, use 'Control.Exception.catch' from "Control.Exception".
+catch :: IO a -> (IOError -> IO a) -> IO a
+catch = New.catch
+#endif /* !__HUGS__ */