Make Control.Exception buildable by nhc98.

The nhc98 does not have true exceptions, but these additions should be
enough infrastructure to pretend that it does.  Only IO exceptions will
actually work.

diff --git a/Control/Exception.hs b/Control/Exception.hs
index 1a40780..e52f674 100644 (file)
--- a/Control/Exception.hs
+++ b/Control/Exception.hs
@@ -143,6 +143,52 @@ import System.IO.Error     hiding ( catch, try )
 import System.IO.Unsafe (unsafePerformIO)
 import Data.Dynamic
 
+#ifdef __NHC__
+import System.IO.Error (catch, ioError)
+import IO              (bracket)
+import DIOError                -- defn of IOError type
+
+-- minimum needed for nhc98 to pretend it has Exceptions
+type Exception  = IOError
+type IOException = IOError
+data ArithException
+data ArrayException
+data AsyncException
+
+throwIO         :: Exception -> IO a
+throwIO   = ioError
+throw   :: Exception -> a
+throw     = unsafePerformIO . throwIO
+
+evaluate :: a -> IO a
+evaluate x = x `seq` return x
+
+ioErrors       :: Exception -> Maybe IOError
+ioErrors e       = Just e
+arithExceptions :: Exception -> Maybe ArithException
+arithExceptions  = const Nothing
+errorCalls     :: Exception -> Maybe String
+errorCalls       = const Nothing
+dynExceptions  :: Exception -> Maybe Dynamic
+dynExceptions    = const Nothing
+assertions     :: Exception -> Maybe String
+assertions       = const Nothing
+asyncExceptions :: Exception -> Maybe AsyncException
+asyncExceptions  = const Nothing
+userErrors     :: Exception -> Maybe String
+userErrors (UserError _ s) = Just s
+userErrors  _              = Nothing
+
+block   :: IO a -> IO a
+block    = id
+unblock :: IO a -> IO a
+unblock  = id
+
+assert :: Bool -> a -> a
+assert True  x = x
+assert False _ = throw (UserError "" "Assertion failed")
+#endif
+
 -----------------------------------------------------------------------------
 -- Catching exceptions
 
@@ -191,12 +237,12 @@ import Data.Dynamic
 --
 -- and then using @C.catch@
 --
-
+#ifndef __NHC__
 catch          :: IO a                 -- ^ The computation to run
        -> (Exception -> IO a)  -- ^ Handler to invoke if an exception is raised
        -> IO a                 
 catch =  ExceptionBase.catchException
-
+#endif
 -- | The function 'catchJust' is like 'catch', but it takes an extra
 -- argument which is an /exception predicate/, a function which
 -- selects which type of exceptions we\'re interested in.  There are
@@ -289,7 +335,11 @@ tryJust p a = do
 -- | Raise any value as an exception, provided it is in the
 -- 'Typeable' class.
 throwDyn :: Typeable exception => exception -> b
+#ifdef __NHC__
+throwDyn exception = throw (UserError "" "dynamic exception")
+#else
 throwDyn exception = throw (DynException (toDyn exception))
+#endif
 
 #ifdef __GLASGOW_HASKELL__
 -- | A variant of 'throwDyn' that throws the dynamic exception to an
@@ -307,6 +357,9 @@ throwDynTo t exception = throwTo t (DynException (toDyn exception))
 -- with dynamic exceptions used in other libraries.
 --
 catchDyn :: Typeable exception => IO a -> (exception -> IO a) -> IO a
+#ifdef __NHC__
+catchDyn m k = m       -- can't catch dyn exceptions in nhc98
+#else
 catchDyn m k = catchException m handle
   where handle ex = case ex of
                           (DynException dyn) ->
@@ -314,6 +367,7 @@ catchDyn m k = catchException m handle
                                    Just exception  -> k exception
                                    Nothing -> throw ex
                           _ -> throw ex
+#endif
 
 -----------------------------------------------------------------------------
 -- Exception Predicates
@@ -322,7 +376,7 @@ catchDyn m k = catchException m handle
 -- These pre-defined predicates may be used as the first argument to
 -- 'catchJust', 'tryJust', or 'handleJust' to select certain common
 -- classes of exceptions.
-
+#ifndef __NHC__
 ioErrors               :: Exception -> Maybe IOError
 arithExceptions        :: Exception -> Maybe ArithException
 errorCalls             :: Exception -> Maybe String
@@ -351,7 +405,7 @@ asyncExceptions _ = Nothing
 
 userErrors (IOException e) | isUserError e = Just (ioeGetErrorString e)
 userErrors _ = Nothing
-
+#endif
 -----------------------------------------------------------------------------
 -- Some Useful Functions
 
@@ -374,6 +428,7 @@ userErrors _ = Nothing
 --
 -- > withFile name mode = bracket (openFile name mode) hClose
 --
+#ifndef __NHC__
 bracket 
        :: IO a         -- ^ computation to run first (\"acquire resource\")
        -> (a -> IO b)  -- ^ computation to run last (\"release resource\")
@@ -388,7 +443,7 @@ bracket before after thing =
     after a
     return r
  )
-   
+#endif
 
 -- | A specialised variant of 'bracket' with just a computation to run
 -- afterward.
@@ -503,7 +558,7 @@ Similar arguments apply for other interruptible operations like
 'System.IO.openFile'.
 -}
 
-#ifndef __GLASGOW_HASKELL__
+#if !(__GLASGOW_HASKELL__ || __NHC__)
 assert :: Bool -> a -> a
 assert True x = x
 assert False _ = throw (AssertionFailed "")

diff --git a/Makefile.nhc98 b/Makefile.nhc98
index f8c9684..2b8f7d0 100644 (file)
--- a/Makefile.nhc98
+++ b/Makefile.nhc98
@@ -1,5 +1,6 @@
 THISPKG        = base
-SEARCH = -I$(TOPDIR)/targets/$(MACHINE) -Iinclude
+SEARCH = -I$(TOPDIR)/targets/$(MACHINE) -Iinclude \
+         -I../../prelude/PreludeIO -I../../prelude/`harch`
 EXTRA_H_FLAGS   = -H4M -K3M
 EXTRA_HBC_FLAGS = -H16M -A1M
 
@@ -16,6 +17,7 @@ SRCS  = \
        Data/Function.hs Data/Graph.hs \
        Control/Monad.hs Control/Monad/Fix.hs Control/Monad/Instances.hs \
        Control/Arrow.hs Control/Applicative.hs \
+       Control/Exception.hs \
        Debug/Trace.hs \
        NHC/SizedTypes.hs NHC/PosixTypes.hsc \
        System/IO.hs System/IO/Error.hs System/IO/Unsafe.hs \