haskell - simpel Haskell 列表按模式排序/洗牌

Question

我正在尝试制作一种算法，该算法接收列表并根据以下操作步骤重新组织列表。

[1 , 2, 3, 4 , 5, 6, 7 , 8, 9 ]
[1 , 3, 5 , 7, 9 ] ++ [2 , 4, 6, 8 ]
[1 , 3, 5 , 7, 9 ] ++ [2 , 6] ++ [ 4, 8 ]
[1 , 3, 5 , 7, 9 , 2, 6 , 4, 8 ]

我已经走到这一步了，然后我不知道下一步该做什么。有什么帮助吗？

ever xs = if xs == [] then [ ] else head xs: ever (drop 1 residue)
    Where residue 1 drop = xs

Answer 1

这是 CPS 版本:

shuffle [] = []
shuffle xs = shuffle' xs shuffle where
    shuffle' (x:y:xs) cont = x : shuffle' xs (cont . (y:))
    shuffle'      xs  cont = xs ++ cont []