Re: [Haskell-cafe] Existentially-quantified constructors, Eq and Show

8 Dec 2005

      Joel Reymont wrote:
...
Folks,
Is there a less verbose way of doing this:
data State a
    = Start
    | Stop
    | (Show a, Eq a) => State a
I'm curious, what is the difference between the above and...

        data State a = Start 
                     | Stop  
                     | State a  deriving (Show, Eq)

...Does it give better error messages at compile time or something?

Thanks,

Greg Buchholz