map! evaluates twice

[Salih Dincer]

On Friday, 10 June 2022 at 22:10:10 UTC, Ali Çehreli wrote:
> [...] I am trying to finish a .cached range algorithm that 
> caches all elements that are in use. (It must drop old elements 
> so that an infinite range does not require infinite cache.)
>
> It is supposed to evaluate elements only once.

I guess the developed cached() and cache() are different things, 
right? I tried cached(), it works fine and cleverly designed...

SDB at 79