The point is not that you can do explicit casts, it's that because you can form a (fake) instance for impossible types you can do invalid type conversions without doing anything that looks unsafe.
In Haskell you can certainly achieve the same thing with various common extensions ( http://okmij.org/ftp/Haskell/impredicativity-bites.html ). Possibly not in vanilla Haskell '98, at the price of being not a very nice language to work in. (A total language like Idris should permit GADT-like functionality without allowing this kind of issue).
In Haskell you can certainly achieve the same thing with various common extensions ( http://okmij.org/ftp/Haskell/impredicativity-bites.html ). Possibly not in vanilla Haskell '98, at the price of being not a very nice language to work in. (A total language like Idris should permit GADT-like functionality without allowing this kind of issue).