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

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