[ewrcoffee]

If you are already a haskell shop and need some way to write JSON schema, this probably doesn't seem too much over engineer. On the other hand, if the purpose is just to limit the expressiveness of JSON schema, I think a runtime checking is more than enough (that's how we solved our problem). Since any data schema we write inevitably has a "validation" phase during our build process. And doing runtime checking during the build phrase allows more flexible and extensible validation; with less abstraction to be understood by the strawman.