diff options
Diffstat (limited to 'src/GF/Data/Operations.hs')
| -rw-r--r-- | src/GF/Data/Operations.hs | 15 |
1 files changed, 8 insertions, 7 deletions
diff --git a/src/GF/Data/Operations.hs b/src/GF/Data/Operations.hs index c297bc55a..ce8f90a03 100644 --- a/src/GF/Data/Operations.hs +++ b/src/GF/Data/Operations.hs @@ -5,9 +5,9 @@ -- Stability : (stable) -- Portability : (portable) -- --- > CVS $Date: 2005/05/30 18:39:44 $ --- > CVS $Author: aarne $ --- > CVS $Revision: 1.20 $ +-- > CVS $Date: 2005/11/01 20:09:04 $ +-- > CVS $Author: bringert $ +-- > CVS $Revision: 1.21 $ -- -- some auxiliary GF operations. AR 19\/6\/1998 -- 6\/2\/2001 -- @@ -100,6 +100,7 @@ data Err a = Ok a | Bad String instance Monad Err where return = Ok + fail = Bad Ok a >>= f = f a Bad s >>= f = Bad s @@ -302,19 +303,19 @@ isInBinTree :: (Ord a) => a -> BinTree a b -> Bool isInBinTree x = err (const False) (const True) . justLookupTree x -- isInBinTree = elemFM -justLookupTree :: (Ord a) => a -> BinTree a b -> Err b +justLookupTree :: (Monad m,Ord a) => a -> BinTree a b -> m b justLookupTree = lookupTree (const []) -lookupTree :: (Ord a) => (a -> String) -> a -> BinTree a b -> Err b +lookupTree :: (Monad m,Ord a) => (a -> String) -> a -> BinTree a b -> m b lookupTree pr x tree = case tree of - NT -> Bad ("no occurrence of element" +++ pr x) + NT -> fail ("no occurrence of element" +++ pr x) BT (a,b) left right | x < a -> lookupTree pr x left | x > a -> lookupTree pr x right | x == a -> return b --lookupTree pr x tree = case lookupFM tree x of -- Just y -> return y --- _ -> Bad ("no occurrence of element" +++ pr x) +-- _ -> fail ("no occurrence of element" +++ pr x) lookupTreeMany :: Ord a => (a -> String) -> [BinTree a b] -> a -> Err b lookupTreeMany pr (t:ts) x = case lookupTree pr x t of |