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 | jochem@functor.nl GPG: 0xE6FABFAB