継続渡し的なsplit

replace.hs

replace :: Int -> Int -> [a] -> [a]
replace i j xs | 0 <= i && i < j && j < length xs = mkHead . (:) xj . mkBody . (:) xi $ tail
	       | null xs   = []
               | otherwise = xs
  where
    (mkHead, (xi:bodyTail)) = splitCps i xs id
    (mkBody, (xj:tail))     = splitCps (j - i - 1) bodyTail id

splitCps :: Int -> [a] -> ([a] -> [a]) -> ([a] -> [a], [a])
splitCps 0 xs f     = (f, xs)
splitCps _ [] f     = (f, [])
splitCps n (x:xs) f = splitCps (n - 1) xs (\ys -> f (x:ys))