On Sun, Jan 19, 2020 at 11:17:54AM +0000, PICCA Frederic-Emmanuel wrote:
..., but this is not what I want :))
I want at the end to split each of my T into chunk of length target.
like this
[[T "1" 0 10], [T "1" 10 20], [T "1" 20 30], [T "2" 0 10], ...]
So a split function like this should be used
split :: Int -> a -> (a, a) split s (T n f t) = (T n f s, T n s t)
{-# LANGUAGE BangPatterns #-} {-# LANGUAGE MultiWayIf #-} {-# LANGUAGE StandaloneDeriving #-} data W n a = W !a !n !n deriving instance (Show n, Show a) => Show (W n a) wget :: W n a -> a wget (W a _ _) = a weight :: Num n => W n a -> n weight (W _ l h) = h - l wsplit :: Num n => W n a -> n -> (W n a, W n a) wsplit (W a l h) n = ( (W a l (l + n)), (W a (l+n) h) ) chunk :: (Num n, Ord n) => n -> [W n a] -> [[W n a]] chunk target = go target target where go tgt _ [] = [] go tgt gap [x] = golast tgt gap x go tgt gap ~(x:xs) = let gap' = gap - weight x in if | gap' > 0 -> cons1 x $ go tgt gap' xs | gap' == 0 -> [x] : go tgt tgt xs | (x1, x2) <- wsplit x gap -> [x1] : go tgt tgt (x2 : xs) cons1 !x ~(c:cs) = (x : c) : cs golast tgt gap x = if | weight x <= gap -> [x] : [] | (x1, x2) <- wsplit x gap -> [x1] : golast tgt tgt x2 {-# SPECIALIZE chunk :: Int -> [W Int a] -> [[W Int a]] #-} -- Viktor.