diff options
Diffstat (limited to 'src/GF/Data/Utilities.hs')
| -rw-r--r-- | src/GF/Data/Utilities.hs | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/src/GF/Data/Utilities.hs b/src/GF/Data/Utilities.hs index 6f93add28..356bf4d1a 100644 --- a/src/GF/Data/Utilities.hs +++ b/src/GF/Data/Utilities.hs @@ -4,9 +4,9 @@ -- Stability : (stable) -- Portability : (portable) -- --- > CVS $Date: 2005/04/11 13:52:49 $ +-- > CVS $Date: 2005/05/09 09:28:44 $ -- > CVS $Author: peb $ --- > CVS $Revision: 1.1 $ +-- > CVS $Revision: 1.2 $ -- -- Basic functions not in the standard libraries ----------------------------------------------------------------------------- @@ -14,6 +14,8 @@ module GF.Data.Utilities where +import Monad (liftM) + -- * functions on lists sameLength :: [a] -> [a] -> Bool @@ -21,6 +23,10 @@ sameLength [] [] = True sameLength (_:xs) (_:ys) = sameLength xs ys sameLength _ _ = False +notLongerThan, longerThan :: Int -> [a] -> Bool +notLongerThan n = null . snd . splitAt n +longerThan n = not . notLongerThan n + lookupList :: Eq a => a -> [(a, b)] -> [b] lookupList a [] = [] lookupList a (p:ps) | a == fst p = snd p : lookupList a ps @@ -42,6 +48,18 @@ foldMerge merge zero = fm fm [a] = a fm abs = let (as, bs) = split abs in fm as `merge` fm bs +select :: [a] -> [(a, [a])] +select [] = [] +select (x:xs) = (x,xs) : [ (y,x:ys) | (y,ys) <- select xs ] + +updateNth :: (a -> a) -> Int -> [a] -> [a] +updateNth update 0 (a : as) = update a : as +updateNth update n (a : as) = a : updateNth update (n-1) as + +updateNthM :: Monad m => (a -> m a) -> Int -> [a] -> m [a] +updateNthM update 0 (a : as) = liftM (:as) (update a) +updateNthM update n (a : as) = liftM (a:) (updateNthM update (n-1) as) + -- * functions on pairs mapFst :: (a -> a') -> (a, b) -> (a', b) |