Possible 'pure' bug with int[] slice. Programming in D page 174

[Dmitry Olshansky]

On Saturday, 4 October 2025 at 10:56:09 UTC, Brother Bill wrote:
> Did I discover a bug, or am I misunderstanding intentional 
> behavior?
> I would not expect a 'pure' function to modify a parameter.

It’s weakly pure in that it could only mutate things that are 
passed in. Strongly pure would require no mutable 
pointers/slices/references.
It may be misleading that it’s single keyword for both of these. 
The good news is that strongly pure functions can call weakly 
pure function and stay strongly pure.