I'm trying to learn Haskell using Hutton's book and Hugs (Sep 06), and am trying to work the parsing examples (chapter 8, Functional parsers), but I can't understand the error I'm seeing when I try to load the program into Hugs. Following the book, I've defined a Parser type, then written the basic parsers, then a sequencing operator >>=, followed by the example p parser (bottom of page 77). However, trying to load this file in Hugs generates an error (caused by the definition of p). I've given below the entire file I've created and the error message I get on trying to load it. Any help much appreciated - Arindam ---------------------------------------- type Parser a = String -> [(a, String)] return :: a -> Parser a return v = \inp -> [(v, inp)] failure :: Parser a failure = \inp -> [] item :: Parser Char item = \inp -> case inp of [] -> [] (x:xs) -> [(x, xs)] parse :: Parser a -> String -> [(a, String)] parse p inp = p inp (>>=) :: Parser a -> (a -> Parser b) -> Parser b p >>= f = \inp -> case parse p inp of [] -> [] [(v, out)] -> parse (f v) out p :: Parser (Char, Char) p = do x <- item item y <- item Main.return (x, y) ------------------------------------------ Hugs> :r ERROR file:c:\parsers.hs:23 - Type error in explicitly typed binding *** Term : p *** Type : [Char] -> [(([(Char,[Char])],[(Char,[Char])]),[Char])] *** Does not match : Parser (Char,Char) Hugs> -- Arindam Roy arind_roy@fast-mail.org -- http://www.fastmail.fm - IMAP accessible web-mail