Re: [Haskell-cafe] Data declaration vs type classes

You can do this using ExistentialQuantification.

On Jan 11, 2016, at 10:15, Guillaume Bouchard <guillaum.bouchard+haskell@gmail.com> wrote:

doAllTask :: [?????] -> IO ()

In this case, GroceryTask and LaundryTask are NOT the same type, hence the "????", you cannot create a list which stores different Tasks and returns apply