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xmlhaskellxml-parsinghxt

How to fix this issue in a simple HXT function?

I've started the friendly tutorial tutorial on HXT to parse XML file with haskell.

In the first page of the tutorial we try to retrieve guest from a xml file. And there is the following function for that.

data Guest = Guest {firstName, lastName :: String}
    deriving (Show, Eq)

getGuest = deep (isElem >>> hasName "guest") >>>                                
 proc x -> do                                                                   
    fname <- getText <<< getChildren <<< deep (hasName "fname") -< x            
    lname <- getText <<< getChildren <<< deep (hasName "lname") -< x            
    returnA -< Guest {firstName = fname, lastName = lname}

but when I tried to load the file in the interpreter ghci. I still get this error :

Prelude> :l hxt_tuto.hs
hxt_tuto.hs:15:37: parse error on input `->'
Failed, modules loaded: none.

pointing the fact that operator -> in the expression proc x -> do has a parse error, I've try many modification without help. like writing all this in a single line

getGuest2 = deep (isElem >>> hasName "guest") >>> proc x -> do { fname <- getText <<< getChildren <<< deep (hasName "fname") -< x; lname <- getText <<< getChildren <<< deep (hasName "lname") -< x; returnA -< Guest {firstName = fname, lastName = lname }}

Can anybody Help me understand what I've missed ?

thanks for any reply!

Solution

  • Did you remember to put

    {-# LANGUAGE Arrows, NoMonomorphismRestriction #-}
import Text.XML.HXT.Core

    at the top of your file?