Re: [Haskell-cafe] Existential quantification of config data types

You can create a readLayer function that returns something like this: * data** OneLayer** =** forall** a. Layer a =>** OneLayer** a* Such that we get: * -- Read next layer* *readLayer** :: Handle -> IO* *OneLayer* Still, I feel that an ADT that combines all types is better as it fits the problem perfectly. Every time you add a new layer it will generate warnings for missing pattern matches. Regards, Sumit