[racket] TR error message

Isn't it possible to have a significantly simpler *printed* type even
if you WERE exploiting this information?  The fact that

  Complex Complex

doesn't type is true even if the type of < were "merely"

  Real Real Real *

That doesn't preclude < from ALSO being of other types, like

  Integer Integer

and so on.  That is, the others are surely subsumed by some more
general type, and the error message can merely print the "least
subsumed" type(s) relative to the arguments.

Shriram