size_t index=-1;

[tsbockman via Digitalmars-d-learn]

On Friday, 18 March 2016 at 05:20:35 UTC, Ola Fosheim Grøstaf 
wrote:
> Only providing modular arithmetics is a significant language 
> design flaw, but as long as all integers are defined to be 
> modular then there is no fundamental semantic difference either.

`ulong.max` and `-1L` are fundamentally different semantically, 
even with two's complement modular arithmetic.

Just because a few operations (addition and subtraction, mainly) 
can use a common implementation for both, does not change that. 
Division, for example, cannot be done correctly without knowing 
whether the inputs are signed or not.