How often I should be using const? Is it useless/overrated?

[Kagamin]

On Friday, 18 November 2022 at 17:57:25 UTC, H. S. Teoh wrote:
> You're looking at it the wrong way.  The kind of issues having 
> const
> would solve is like when your function takes parameters x, y, 
> z, and
> somewhere deep in the function you see the expression `x + 
> y*z`. If x,
> y, and z are const, then you immediately know what the value of 
> this
> expression is.  However, if they were not, then you'd have to 
> trace
> through all of the preceding code to figure out whether their 
> values
> have changed, and how they have changed.  The former makes the 
> code
> easier to understand, the latter adds complexity to 
> understanding the
> code.

AFAIK Rust allows shadowing (intentionally) to solve usability 
problems with immutable variables, so when deep in the function 
you see `x+y*z`, you can't immediately tell its value, because 
the variables could be previously shadowed and you have to trace 
through all of the preceding code to figure it out :)