[英]How to get haskell code after desugaring arrow syntax?
我目前試圖解決我的問題HXT:輸入是否可以改變箭頭語法? 因此,想要在ghc編譯器去掉Arrow語法之后看到haskell代碼。 我怎樣才能做到這一點?
我已經嘗試了-ddump-ds
但是有了這個標志我得到了一個可怕的長代碼,因為所有類型都被解析了。 有沒有辦法看到代碼只用箭頭語法desugaring?
原始箭頭項目提供了一個名為arrowp
的解析器, 可在Hackage上使用 ,並將箭頭語法轉換為Haskell98:
cabal install arrowp
arrowp --help
arrowp source.hs > desugared.hs
來源已從您的其他問題中獲取 。
{-# LANGUAGE Arrows #-}
import Text.XML.HXT.Core
data Person = Person { forname :: String, surname :: String } deriving (Show)
parseXml :: IOSArrow XmlTree Person
parseXml = proc x -> do
forname <- x >- this /> this /> hasName "fn" /> getText
surname <- x >- this /> this /> hasName "sn" /> getText
returnA -< Person forname surname
main :: IO ()
main = do
person <- runX (readString [withValidate no]
"<p><fn>John</fn><sn>Smith</sn></p>"
>>> parseXml)
putStrLn $ show person
return ()
arrowp source.hs
{-# LINE 2 "source.hs" #-}
module Main (main) where
{-# LINE 2 "source.hs" #-}
import Text.XML.HXT.Core
{-# LINE 4 "source.hs" #-}
data Person = Person{forname :: String, surname :: String}
deriving Show
{-# LINE 6 "source.hs" #-}
parseXml :: IOSArrow XmlTree Person
{-# LINE 7 "source.hs" #-}
parseXml
= (arr (\ x -> (x, x)) >>>
(first (this /> this /> hasName "fn" /> getText) >>>
arr (\ (forname, x) -> (x, forname)))
>>>
(first (this /> this /> hasName "sn" /> getText) >>>
arr (\ (surname, forname) -> Person forname surname)))
{-# LINE 12 "source.hs" #-}
main :: IO ()
{-# LINE 13 "source.hs" #-}
main
= do person <- runX
(readString [withValidate no] "<p><fn>John</fn><sn>Smith</sn></p>"
>>> parseXml)
putStrLn $ show person
return ()
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.