Simple GADTs Question

[David Menendez]

J. Garrett Morris writes:

> Hello,
> 
> I'm attempting to use GADTs for the first time, and I'm running into
> an (I think) odd error.  My file includes:
> 
> data DFExpr :: * -> *
>     where Deriv :: (Num t) => t -> Deriv Int (DFExpr t) (DFExpr t)

I think you want something like this:

    Deriv :: Int -> DFExpr t -> DFExpr t -> DFExpr t

Ignorning the other clauses, it's equivalent to

    data DFExpr t = Deriv Int (DFExpr t) (DFExpr t)
-- 
David Menendez <zednenem at psualum.com> | "In this house, we obey the laws
<http://www.eyrie.org/~zednenem>      |        of thermodynamics!"