Re: [Haskell-beginners] Confused by type constraints

On Fri, Jun 3, 2011 at 09:55, Daniel Schoepe wrote:

The constraints in the data type declaration only affect the constructors. It's a known issue, unfortunately there doesn't seem to be a way around it.

GADTs handle it as expected. The core problem is with how the Haskell 98 standard declared them to work; the Haskell standards committee has proposed removing them altogether from non-GADT syntax since they're worse than useless as is.