I have realized (remembered?) that type specifiers are only one of the
ingredients in this particular recipe for solving this problem.

For example, consider the following in Kawa's notation:

   (lambda (x :: <flonum> y :: <flonum>) :: <flonum>
     (/ x y))

Unless the compiler can be sure that / is the standard division
procedure, there is not much it can do.

Of course, module systems often allow the compiler to figure out what /
really is, and a module system will come fitted as standard in R6RS.

Regards,

Alan
--
Dr Alan Watson
Centro de Radioastronomía y Astrofísica
Universidad Astronómico Nacional de México