我正在尝试编写一个函数，该函数接受字符串列表和 Int 并返回其中每个字符串都是“int”次的字符串列表。那是：
duplicate :: [String] -> Int -> [String]
duplicate ["ab","ac","yt","hfg","lkj","poi"] 2
输出应该是
["ab","ab","ac","ac","yt","yt","hfg","hfg","lkj","lkj","poi","poi"]
duplicate = (. replicate) . (>>=)
或更基本的
duplicate xs n = concatMap (replicate n) xs
如果你也想通过符号进行列表乘法
> let (**) :: [a] -> Int -> [a]
| (**) = (. replicate) . (>>=)
> ["a","b"]**3
["a","a","a","b","b","b"]
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