[project @ 1999-06-09 09:35:54 by simonpj]

[ghc-hetmet.git] / ghc / tests / programs / jeff-bug / STEx.hs

diff --git a/ghc/tests/programs/jeff-bug/STEx.hs b/ghc/tests/programs/jeff-bug/STEx.hs
index cb77722..76ed6fb 100644 (file)
--- a/ghc/tests/programs/jeff-bug/STEx.hs
+++ b/ghc/tests/programs/jeff-bug/STEx.hs
@@ -1,5 +1,6 @@
 module STEx where
 import LazyST
+import Monad
 
 infixl 1 `handle`
 
@@ -13,7 +14,6 @@ infixl 1 `handle`
 {-data STEx s a-}
 
 {-instance Monad (STEx s)-}
-{-instance MonadZero (STEx s)-}
 {-instance MonadPlus (STEx s)-}
 
 -- c `handle` x, return x if c raises an exception
@@ -49,13 +49,11 @@ instance Monad (STEx s) where
                                       in z'
                             Nothing -> return Nothing
 
-instance MonadZero (STEx s) where
-       zero = liftEx zero
-
 instance MonadPlus (STEx s) where
-       (STEx x) ++ (STEx y) = STEx $ do x' <- x
-                                         y' <- y
-                                         return $ x' ++ y'
+       mzero = liftEx mzero
+       (STEx x) `mplus` (STEx y) = STEx $ do x' <- x
+                                             y' <- y
+                                             return $ mplus x' y'
 liftST x = STEx $ do {z <- x ; return $ return z}
 
 liftEx x = STEx $ return x