> Clearly this is different to a compiler which intentionally rejects programs that can't be efficiently implemented/compiled. I agree. I wonder what happens

> Clearly this is different to a compiler which intentionally rejects programs that can't be efficiently implemented/compiled. I agree. I wonder what happens when the heuristic fails in the Ur/web compiler. When my C++ compiler runs over its template instantiation depth, I get a nice error message telling me what happened and how to increase the depth.