SomeDude:
I've never had any use for rational numbers as have 99% of developers I believe. Maybe I'm overlooking something, but I see only two possible usages of them: math packages and length quotations in the english system. Because of this, I'd rather see them in Deimos than in Phobos.
I have had to use Rational nunbers in D two or three times (once during simplification of expressions that contain operations among integer numbers, to not lose exact precision with floating point numbers). I have written a rationals module for D1 and later I have converted it to D2. So you see two persons that have implemented them.
It's a small module, that uses std.bigint, it's not a binding to C code, so putting it in Deimos is not necessary. I'd like a rationals module in Phobos.
Bye, bearophile
