zipLazy, stretchZipWith,
mapFst, mapSnd,
mapAndUnzip, mapAndUnzip3,
- nOfThem, filterOut, partitionWith,
+ nOfThem, filterOut, partitionWith, splitEithers,
lengthExceeds, lengthIs, lengthAtLeast,
listLengthCmp, atLength, equalLength, compareLength,
-- comparisons
isEqual, eqListBy,
- thenCmp, cmpList, prefixMatch, suffixMatch, maybePrefixMatch,
+ thenCmp, cmpList, maybePrefixMatch,
removeSpaces,
-- strictness
where
(bs,cs) = partitionWith f xs
+splitEithers :: [Either a b] -> ([a], [b])
+splitEithers [] = ([],[])
+splitEithers (e : es) = case e of
+ Left x -> (x:xs, ys)
+ Right y -> (xs, y:ys)
+ where
+ (xs,ys) = splitEithers es
\end{code}
A paranoid @zip@ (and some @zipWith@ friends) that checks the lists
\end{code}
\begin{code}
-prefixMatch :: Eq a => [a] -> [a] -> Bool
-prefixMatch [] _str = True
-prefixMatch _pat [] = False
-prefixMatch (p:ps) (s:ss) | p == s = prefixMatch ps ss
- | otherwise = False
-
maybePrefixMatch :: String -> String -> Maybe String
maybePrefixMatch [] rest = Just rest
maybePrefixMatch (_:_) [] = Nothing
| p == r = maybePrefixMatch pat rest
| otherwise = Nothing
-suffixMatch :: Eq a => [a] -> [a] -> Bool
-suffixMatch pat str = prefixMatch (reverse pat) (reverse str)
-
removeSpaces :: String -> String
removeSpaces = reverse . dropWhile isSpace . reverse . dropWhile isSpace
\end{code}
%* *
%************************************************************************
-The following are curried versions of @fst@ and @snd@.
-
-\begin{code}
-#if NOT_USED
-cfst :: a -> b -> a -- stranal-sem only (Note)
-cfst x y = x
-#endif
-\end{code}
-
The following provide us higher order functions that, when applied
to a function, operate on pairs.
handleDyn = flip catchDyn
handle :: (Exception -> IO a) -> IO a -> IO a
-#if __GLASGOW_HASKELL__ < 501
-handle = flip Exception.catchAllIO
-#else
handle h f = f `Exception.catch` \e -> case e of
ExitException _ -> throw e
_ -> h e
-#endif
-- --------------------------------------------------------------
-- check existence & modification time at the same time