我想将一些非常简单的文本解析
"abcxyzzzz\nhello\n"
为["abcxyzzz", "hello"] :: String
.
不寻找更简单的函数来执行此操作(例如words
),因为我需要解析更复杂的东西,而我只是在这里奠定基础。
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TypeSynonymInstances #-}
{-# LANGUAGE FlexibleInstances #-}
module RgParse where
import Data.Text (Text)
import Text.Megaparsec
import Text.Megaparsec.Char
data SimpleData = SimpleData String deriving (Eq, Show, Ord)
data SimpleData' = SimpleData' [String] deriving (Eq, Show, Ord)
instance ShowErrorComponent SimpleData where
showErrorComponent = show
instance ShowErrorComponent String where
showErrorComponent = show
simple :: Parsec String Text SimpleData
simple = do
x <- many (noneOf (Just '\n'))
pure $ SimpleData x
simple' :: Parsec String Text SimpleData'
simple' = do
x <- many (many (noneOf (Just '\n')))
pure $ SimpleData' x
example2 :: Text
example2 = "abcxyzzzz\nhello\n"
main :: IO ()
main = do
print "Simple:"
case parse simple "<stdin>" example2 of
Left bundle -> putStr (errorBundlePretty bundle)
Right result -> print result
print "Simple':"
case parse simple' "<stdin>" example2 of
Left bundle -> putStr (errorBundlePretty bundle)
Right result -> print result
print "done.."
不幸的是,上面的内容在输入时遇到了无限循环/空间泄漏,simple'
因为它输出以下内容:
Hello, Haskell!
[]
"Simple:"
SimpleData "abcxyzzzz"
"Simple':"
使用 megaparsec-7.0.5(不是最新的 9.xx)。
是否有更简单的方法来获得多行?