Unfortunately I do not know the fancy Haskell type-level stuff, but if I was looking at this same problem, I'd think you need a sum type: data Unchecked = Unchecked String data Checked = Hd5 String | Cbf String check :: Unchecked -> Checked There is likely a better concept than "Checked" in your domain. I do not know what those things represent, but I would use that *ubiquitous language* instead - i.e., data Image ... instead of Checked. On Tue, Oct 2, 2018 at 12:05 PM PICCA Frederic-Emmanuel < frederic-emmanuel.picca@synchrotron-soleil.fr> wrote:
I believe you can do this with GADTs [1]
I can create different constructors for the different types. but how can I create a function which return different type ?
Fred _______________________________________________ Beginners mailing list Beginners@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
-- Steven Leiva 305.528.6038 leiva.steven@gmail.com http://www.linkedin.com/in/stevenleiva