diff options
Diffstat (limited to 'src/GF/Data')
| -rw-r--r-- | src/GF/Data/Utilities.hs | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/src/GF/Data/Utilities.hs b/src/GF/Data/Utilities.hs index fbe6c6a27..d7e6be2f0 100644 --- a/src/GF/Data/Utilities.hs +++ b/src/GF/Data/Utilities.hs @@ -4,9 +4,9 @@ -- Stability : (stable) -- Portability : (portable) -- --- > CVS $Date: 2005/09/22 16:56:05 $ +-- > CVS $Date: 2005/10/26 18:47:16 $ -- > CVS $Author: bringert $ --- > CVS $Revision: 1.5 $ +-- > CVS $Revision: 1.6 $ -- -- Basic functions not in the standard libraries ----------------------------------------------------------------------------- @@ -76,6 +76,10 @@ safeInit xs = init xs sortNub :: Ord a => [a] -> [a] sortNub = map head . group . sort +-- | Like 'nubBy', but more efficient as it uses sorting internally. +sortNubBy :: (a -> a -> Ordering) -> [a] -> [a] +sortNubBy f = map head . groupBy (compareEq f) . sortBy f + -- | Take the union of a list of lists. unionAll :: Eq a => [[a]] -> [a] unionAll = nub . concat @@ -89,6 +93,14 @@ lookup' x = fromJust . lookup x find' :: (a -> Bool) -> [a] -> a find' p = fromJust . find p +-- * equality functions + +-- | Use an ordering function as an equality predicate. +compareEq :: (a -> a -> Ordering) -> a -> a -> Bool +compareEq f x y = case f x y of + EQ -> True + _ -> False + -- * ordering functions compareBy :: Ord b => (a -> b) -> a -> a -> Ordering |