Haskell获取列表的第一个Char并附加到该列表的末尾

Question

假设：

mangle :: String -> String

我想做类似的事情：

mangle xs = head xs -- works if you change typesig to [a] -> a

但：

mangle xs = tail xs ++ head xs -- won't work at all!

想在列表的末尾追加列表的第一个字符，删除第一个字符。

Answer 1

非常直接的解决方案可能如下所示：

mangle :: String -> String
mangle [] = []
mangle (x:xs) = xs ++ [x]