>
>
> Is that an invariant you expect to apply to other uses of the +
> operator?
>
> py> x = -1
> py> x <= (x + x)
> False
>
> py> [999] <= ([1, 2, 3] + [999])
> False
>
Please calm down. I meant each type implements "sum"
in semantics of the type, in lossless way.
What "lossless" means is changed by the semantics of the type.
-1 + -1 = -2 is sum in numerical semantics. There are no loss.
TBH I don't understand what is lossless about numeric addition. What is the definition of lossless?
Clearly some information is lost, since you can't uniquely restore two numbers you add from the result.
Unless you define what lossless means, there will be just more misunderstandings.
--
Ivan