Re: [Haskell-beginners] Could not get parser ready

Hey, can you show us your Parser definition?  Cheers, Tobias  ----- Nachricht von Marcus Manning ---------      Datum: Sun, 5 Nov 2017 18:51:57 +0100        Von: Marcus Manning Antwort an: The Haskell-Beginners Mailing List - Discussion of primarily beginner-level topics related to Haskell    Betreff: [Haskell-beginners] Could not get parser ready         An: beginners@haskell.org

Hello,

I follow the instructions of script [1] in order to set up a parser functionality. But I' get into problems at page 202 with the code:

p :: Parser (Char,Char) p = do              x ← item              item              y ← item              return (x,y)

ghci and ghc throw errors: Prelude> let p:: Parser (Char,Char); p = do {x <- item; item; y <- item; return (x,y)}

<interactive>:10:65: error:     • Couldn't match type ‘[(Char, String)]’ with ‘Char’       Expected type: String -> [((Char, Char), String)]         Actual type: Parser ([(Char, String)], [(Char, String)])     • In a stmt of a 'do' block: return (x, y)       In the expression:         do x <- item            item            y <- item            return (x, y)       In an equation for ‘p’:           p = do x <- item                  item                  y <- item                  .... Did the semantics of do expr changed?

[1] https://userpages.uni-koblenz.de/~laemmel/paradigms1011/resources/pdf/haskel...

Cheers,

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