Move some catch definitions around to avoid an import loop

As suggested by simonpj in trac #2822.

diff --git a/Prelude.hs b/Prelude.hs
index 4f01b9f..61bd27e 100644 (file)
--- a/Prelude.hs
+++ b/Prelude.hs
@@ -146,6 +146,7 @@ module Prelude (
 #ifndef __HUGS__
 import Control.Monad
 import System.IO
+import System.IO.Error
 import Data.List
 import Data.Either
 import Data.Maybe
@@ -164,10 +165,6 @@ import GHC.Show
 import GHC.Err   ( error, undefined )
 #endif
 
-#ifndef __HUGS__
-import qualified Control.Exception.Base as New (catch)
-#endif
-
 #ifdef __HUGS__
 import Hugs.Prelude
 #endif
@@ -190,26 +187,3 @@ f $! x  = x `seq` f x
 seq :: a -> b -> b
 seq _ y = y
 #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__ */

diff --git a/Prelude.hs-boot b/Prelude.hs-boot
deleted file mode 100644 (file)
index 12a9fd3..0000000
--- a/Prelude.hs-boot
+++ /dev/null
@@ -1,7 +0,0 @@
-{-# OPTIONS_GHC -XNoImplicitPrelude #-}
-
-module Prelude where
-
-import GHC.IOBase
-
-catch :: IO a -> (IOError -> IO a) -> IO a

diff --git a/System/IO/Error.hs b/System/IO/Error.hs
index fcbffad..372bb15 100644 (file)
--- a/System/IO/Error.hs
+++ b/System/IO/Error.hs
@@ -91,13 +91,15 @@ module System.IO.Error (
   ) where
 
 #ifndef __HUGS__
+import qualified Control.Exception.Base as New (catch)
+#endif
+
+#ifndef __HUGS__
 import Data.Either
 #endif
 import Data.Maybe
 
 #ifdef __GLASGOW_HASKELL__
-import {-# SOURCE #-} Prelude (catch)
-
 import GHC.Base
 import GHC.IOBase
 import Text.Show
@@ -391,3 +393,26 @@ annotateIOError (UserError loc msg) msg' file' hdl' =
 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__ */