The example given with acceleration, velocity, and position? How is a compiler going to deal with that? With an Euler integrator, you say? (every frame, p=p+time_scaled(v), v=v+time_scaled(a) ). Note there's an implied time, as well as frames per second, in there, but a compiler can know about time. Unless when you're saying "acceleration" you're not talking about real time, but calculating where something will be at…
I have to say, I don't know his actual response, but he gives a hint within the article that perhaps, when one wants to get performance in algorithms, one will start to look at the way the constraints are phrased. So when you've got to write a sort, you probably start in our hypothetical dream language by saying: "sort permutes a list so that a Now "permute", with predicates, is probably built into the system and the…
Aside from that, sort IS something that's so common that it tends to be implemented in every high level programming environment in one way or another. Baking several sorts into a language isn't odd, so I don't think "sort" is a good example, because I ALREADY can say "take this list and sort it" in any language I use.
An Euler integrator isn't built in to anything but a DSL for animations or games, though. And it's one of THOUSANDS (millions?) of algorithms that a program might need -- most of which are more easily described (by the programmer) in a traditional language than by trying to jump through hoops to describe what you want in a way that you'll actually get what you want.
So yes, the trivial problems could be solved by such a language -- but they're already solved by CURRENT languages. It's the hard problems where it would be hard to know how to even start to create a "describe the results" language. I think all you'd end up with is a DSL for each of the cases you thought to describe -- which, depending on the domain, could be useful for that domain. DSLs are great when they're well designed. But as someone else pointed out, you don't write a game in SQL.