Just to clarify so people don’t misinterpret me again. Rust is a great language. It supports FP and I love FP. Rust authors managed to make a lot of this right. But creating a new great language is an easy problem. Not in a sense that it’s trivial. But in a sense that new languages are not encumbered with legacy decisions. They don’t have to make hard choices (yet) to maintain backwards compatibility. They can reap the benefits of other’s mistakes and just don’t introduce them from the start. It’s much harder to actually improve an existing language in a meaningful way and make lives of millions of devs easier without breaking things. It’s a slow and arduous process. I know it. But assuming you can easily rewrite existing software to a new shiny language is naive beyond delusional. In 10 years, Rust will suffer the exact same problem as C++ They won’t be able to add new exciting features without breaking stuff. So they’ll have to make compromises. And devs will start complaining that Rust has a dozen ways to do the same thing. You know what else will happen in the next 40 years? A dozen of new programming languages. It’s very naive to think we achieved a global optimum of programming languages today and Rust is the best we can ever create. Programming Language Theory advances every year, and in 10-20 years we can easily see a new exciting language with groundbreaking innovations. What we’ll have is an ever growing zoo of languages. Software Engineers will be expected to know even more languages and switch between them even quicker. The cycle continues.

In this sense, a good language is one that can bear a huge legacy, survive, and continue to develop. C++ is a good language.