`const` is for compile-time constants where something like `let` in Rust can be used for values generated on the fly.
The latter is immensely more powerful and actually provides the described benefits like guaranteeing that data is not changing under your feet.
Edit: While `const PI = 3.1415…` is threadsafe, it's not very useful in comparison to runtime-immutability :)
Has anyone tested the difference between Mozilla's Firefox build and a local fully-optimized for your machine build?
Or something similar with another piece of open source software.
I wonder how much the "Gentoo-model" of compiling everything yourself affects everyday performance.
https://coq.inria.fr/faq?q=node/16&som=2#htoc4