This is a similar challenge to e.g. C++. Can it be done with SFINAE? Yeah, probably.

Does Servant need pseudo-dependent types and does Wren need lenses?

Maybe we could both make and respond to an HTTP request without getting into some pretty heavy shit?

I think there is a tension between the power of the type system which anyone in userland can use, and wanting to make things easy for the everyday programmer.

What might help is a complete standard library framework akin to what C# provides out of the box that everyone agrees to use unless there is good reason not to.

Also allow imperative syntax.