On 11/10/2017 11:33 AM, raffaello.giulietti@lifeware.ch wrote:
Doing only Fraction->Float conversions in mixed mode won't preserve = as an equivalence relation and won't enable a consistent ordering with <=, which probably most Smalltalkers consider important and enjoyable properties. Good point. I agree that Float -> Fraction is the more desirable mode for implicit conversion, since it can always be done without changing the value. Nicolas gave some convincing examples on why most programmers might want to rely on them.
Also, as I mentioned, most Smalltalkers might prefer keeping away from the complex properties of Floats. Doing automatic, implicit Fraction->Float conversions behind the scenes only exacerbates the probability of encountering Floats and of having to deal with their weird and unfamiliar arithmetic. One problem is that we make it easy to create Floats in source code (0.1), and we print Floats in a nice decimal format but by default print Fractions in their reduced fractional form. If we didn't do this, Smalltalkers might not be working with Floats in the first place, and if they did not have any Floats in their computation they would never run into an implicit conversion to *or* from Float.
As it is, if we were to uniformly do Float -> Fraction conversion on mixed-mode operations, we would get things like (0.1 * (1/1)) printString                      --> '3602879701896397/36028797018963968' Not incredibly friendly. Regards, -Martin