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kotlinlang

is there a unifying comparable class to which all primitive numbers belong, or better yet, one on which you can use mathematical operators?

I think `Number` is the closest thing to what you’re asking for

It might not necessarily define operators, though

unfortunately i can't compare any primitive number types to Number... tried

it looks like `Int`, for example, extends `Number` and implements `Comparable&lt;Int&gt;`, so I don’t think there’s another intermediate type that does the same

I'm making a `RestrictedNumber` delegate(s), starting with `RestrictedInt`, and it'd be nice to not have to make a `compareTo()` for every number type

yep, that's what i saw myself, and just wondered if I was missing something

I'm going to keep saying this but _you can't do anything with a Number!_ You can't write code to compare them, you can't do write code to do math with them.

Well it's a fundamental problem, they could't have "fixed" that.

I'm intrigued. What makes it fundamental?

because the bit twiddling doesn't work out? you'd always have to convert one?

Let's say I have a `Fraction: Number` and a `BigInteger: Number`, and I add them. Now what? Neither fits into the other. In general there might be tens of Number implementations that then all need to be math-compatible with each other.

so why can't we add ints to longs, or floats to doubles?

I'm not even talking about the bit fiddling side or whatever, just the polymorphism part.

i just always found it strange that kotlin didn't include the autocasting to larger types like int -&gt; long, int -&gt; double, etc

because you don't lose or corrupt any data doing that

Yeah that's kind of annoying, I agree with you there. When I say that this is a fundamental problem I mean there's nothing you can write in a function like `fun add(x: Number, y: Number): Number` that makes it work out.

yeah, and therefore you can't either create your own number types easily either. you can do it, it's just tedious to make universally operable and comparable

(it's impossible, there's no way to know all other implementations in advance)

what's impossible? making a generic comparable and operable number type?