I'd like to point out that the example at the end of the blog post is only runnable in GHC 7.6 and Older. As of GHC 7.8, you can't define your own custom typeab

I'd like to point out that the example at the end of the blog post is only runnable in GHC 7.6 and Older. As of GHC 7.8, you can't define your own custom typeable methods, you can only ask GHC to derive a typeable instance