I agree with pinard, although I think it is a manageable problem. I went through this transition once, from Symbolics Lisp, in which integer division truncates, to Common Lisp, in which it produces a rational. After only an hour or two of fiddling with my various programs, everything seemed to work; I was very happy. But after a few days, the machine started to slow down mysteriously, especially on wake-up. It took a while to discover the culprit was my screensaver program (which I hadn't checked) -- it was displaying fish on the screen, and the coordinates of the fish had become rationals quotients of thousand-digit numbers. -Peter pinard@iro.umontreal.ca writes:

While I agree with the theoretical arguments, I have the practical fear that rationals could grow very big, rather quickly, in the course of a long computation involving them in various ways. By big, I mean the numerator and denominator of the fraction taken in isolation, not the number itself.