Question

我希望将输入作为列表列表。每行文本必须是字符串列表，全文将是列表列表。我怎么能这样做？我把它作为主要的：

main :: IO ()
main = interact (lines >>> foo >>> unlines)

所以如果这是输入：

These are random
Words of text
example example example

结果应该是这样的：

[[These, are, random], [Words, of, text],[example, example, example]]

Answer 1

Haskell有一个函数words :: String -> [String]。例如：

Prelude> words "These are random"
["These","are","random"]

现在我们可以使用map :: (a -> b) -> [a] -> [b]：

为行列表执行此操作

Prelude> map words ["These are random","Words of text","example example example"]
[["These","are","random"],["Words","of","text"],["example","example","example"]]

您可以将其与lines结合使用，首先提取字符串的行：

Prelude> (map words . lines) "These are random\nWords of text\nexample example example"
[["These","are","random"],["Words","of","text"],["example","example","example"]]

因此，如果foo的类型为foo :: [[String]] -> [[String]]，则可以使用：

main = interact (unlines . map unwords . foo . map words . lines)

获取[[String]] Haskell的输入

1 个答案: