You can actually encode his example in just regular Haskell98 using type classes, without having to use GADTs: http://www.cs.rutgers.edu/~ccshan/tagless/jfp.pdf

You can actually encode his example in just regular Haskell98 using type classes, without having to use GADTs: http://www.cs.rutgers.edu/~ccshan/tagless/jfp.pdf http://www.cs.rutgers.edu/~ccshan/tagless/jfp.pdf Though, it comes with some loss of clarity. And might hurt your brain.