const is not about types

[JeffBezanson]

The WhyJulia page states that "const is about types, it acts slightly differently than one would expect. const is a declaration that the type of a will be constant, not the value". This is completely false. The compiler indeed assumes that constants will not change value. This is why we print a warning. We don't just print warnings for the hell of it; if you see a warning something is definitely wrong. In this case your program could break in all kinds of ways, but we allow it for convenience to reduce the need to restart julia.

[ChrisRackauckas]

Yes, I was wrong about this 2 years ago and haven't changed it. Some old blog posts might have this too. I'll get this fixed.