[Haskell-cafe] parse error on input `'
Hi, I've defined the following datatype with haskell data Graph a b = Empty | Context a b Graph a b But I am having the error message: parse error on input `' . I am wondering what it is wrong with my definition. How can I fix this? Thanks in advance. Kind regards ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] parse error on input `'
Am Samstag 25 April 2009 19:29:30 schrieb siso dagbovie: Hi, I've defined the following datatype with haskell data Graph a b = Empty | Context a b Graph a b But I am having the error message: parse error on input `' . I am wondering what it is wrong with my definition. How can I fix this? Thanks in advance. A constructor symbol has to start with a colon, so make it data Graph a b = Empty | Context a b : Graph a b (or :: if you prefer it more symmetric) Kind regards Cheers, Daniel ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] parse error on input `'
siso dagbovie wrote: I've defined the following datatype with haskell data Graph a b = Empty | Context a b Graph a b But I am having the error message: parse error on input `' . I am wondering what it is wrong with my definition. How can I fix this? Constructors have to start with a capital or a : (colon). So changing your definition into data Graph a b = Empty | Context a b : Graph a b will work. If you want you can define () = (:) and use the symbol for constructing graphs (not in pattern matches though). HTH, -- Jochem Berndsen | joc...@functor.nl GPG: 0xE6FABFAB ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Parse error on input |
Hi everyone. I am new to this Forum, Haskell and i am german, so i am sorry for noob failures or spelling mistakes. I am currently learning for an informatic exam (11th class) and i tried to code a function to sum a polynom with a pair of polynoms... (I actually want to to code a polynomdivision in which i need this) But I get the parse error mentioned in the headline. It is referring to the first line of the case differentiation. Hopefully you can help me, here's the code: polyplusd :: Polynom - (Polynom, Polynom) - Polynom polyplusd [] p = p polyplusd p [] = p polyplusd p@((g1,e1):p1) (n, (q@((g2,e2):p2)) | g1g2 = (g1,e1):(polyplusd p1 (n,q)) | g2g1 = (g2,e2):(polyplusd p (n,p2)) | g1==g2 e1+e2 /=0 =(g1, e1+e2):(polyplusd p1 (n,p2)) | otherwise = polyplusd p1 (n,p2) -- View this message in context: http://www.nabble.com/Parse-error-on-input-%22%7C%22-tf3847082.html#a10895849 Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Parse error on input |
You neglected a ) - remember to count your parentheses in future when you get an error directly after a parenthesised expression. -- Robin On Thu, 31 May 2007 08:09:23 -0700 (PDT) Akijmo [EMAIL PROTECTED] wrote: Hi everyone. I am new to this Forum, Haskell and i am german, so i am sorry for noob failures or spelling mistakes. I am currently learning for an informatic exam (11th class) and i tried to code a function to sum a polynom with a pair of polynoms... (I actually want to to code a polynomdivision in which i need this) But I get the parse error mentioned in the headline. It is referring to the first line of the case differentiation. Hopefully you can help me, here's the code: polyplusd :: Polynom - (Polynom, Polynom) - Polynom polyplusd [] p = p polyplusd p [] = p polyplusd p@((g1,e1):p1) (n, (q@((g2,e2):p2)) | g1g2 = (g1,e1):(polyplusd p1 (n,q)) | g2g1 = (g2,e2):(polyplusd p (n,p2)) | g1==g2 e1+e2 /=0 =(g1, e1+e2):(polyplusd p1 (n,p2)) | otherwise = polyplusd p1 (n,p2) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Parse error on input |
The second argument of the second line of the definition does not match the expected type. (Polynom,Polynom) is a tuple, not a list, so []::(a,a) is not well typed for any a. Dan Akijmo wrote: Hi everyone. I am new to this Forum, Haskell and i am german, so i am sorry for noob failures or spelling mistakes. I am currently learning for an informatic exam (11th class) and i tried to code a function to sum a polynom with a pair of polynoms... (I actually want to to code a polynomdivision in which i need this) But I get the parse error mentioned in the headline. It is referring to the first line of the case differentiation. Hopefully you can help me, here's the code: polyplusd :: Polynom - (Polynom, Polynom) - Polynom polyplusd [] p = p polyplusd p [] = p polyplusd p@((g1,e1):p1) (n, (q@((g2,e2):p2)) | g1g2 = (g1,e1):(polyplusd p1 (n,q)) | g2g1 = (g2,e2):(polyplusd p (n,p2)) | g1==g2 e1+e2 /=0 =(g1, e1+e2):(polyplusd p1 (n,p2)) | otherwise = polyplusd p1 (n,p2) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Parse error on input |
thx much green... this helped for the parser failure. Dan you were right too, cause now i got the interfering types [(Int,Int)] and Polynom for line 2. But i fixed this by replacing it with ([],[]) So thx much guys :D greenrd wrote: You neglected a ) - remember to count your parentheses in future when you get an error directly after a parenthesised expression. -- Robin On Thu, 31 May 2007 08:09:23 -0700 (PDT) Akijmo [EMAIL PROTECTED] wrote: Hi everyone. I am new to this Forum, Haskell and i am german, so i am sorry for noob failures or spelling mistakes. I am currently learning for an informatic exam (11th class) and i tried to code a function to sum a polynom with a pair of polynoms... (I actually want to to code a polynomdivision in which i need this) But I get the parse error mentioned in the headline. It is referring to the first line of the case differentiation. Hopefully you can help me, here's the code: polyplusd :: Polynom - (Polynom, Polynom) - Polynom polyplusd [] p = p polyplusd p [] = p polyplusd p@((g1,e1):p1) (n, (q@((g2,e2):p2)) | g1g2 = (g1,e1):(polyplusd p1 (n,q)) | g2g1 = (g2,e2):(polyplusd p (n,p2)) | g1==g2 e1+e2 /=0 =(g1, e1+e2):(polyplusd p1 (n,p2)) | otherwise = polyplusd p1 (n,p2) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- View this message in context: http://www.nabble.com/Parse-error-on-input-%22%7C%22-tf3847082.html#a10899124 Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
