haskell中的字符串流

Question

我想l = ["","a","aa","aaa",...]在haskell中创建这个流 .

有人能帮我吗？

Answer 1

将重复组合在一起:

?: let l = inits $ repeat 'a'
?: take 10 l
["","a","aa","aaa","aaaa","aaaaa","aaaaaa","aaaaaaa","aaaaaaaa","aaaaaaaaa"]

Answer 2

我们可以通过迭代地将元素集中到空列表中来实现

iterate :: (a -> a) -> a -> [a]

只是做

iterate ('a':) ""