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Comment by rapsey | Hacker News Reader

Because they are grasping for reasons not to learn Rust.

Their reasoning is reasonable. And besides, when your existing team is already proficient in Cpp, arguing that "they should learn X instead" seems very risky and unwise.

Then just say so and it is fine. We are a team of c++ experts and we are able to build a high quality program in C++ is a completely valid unassailable reason. Except for the most ardent rust fanatic.

Rewriting an existing working codebase rather than committing to its incremental improvement is usually a sign of bad decision making. So I'd be concerned if a team that had an existing mature codebase in C++ and a team of engineers hired on that path were taking on such a venture.

But that's kinda... not a bloggable topic, frankly.

Rust was designed to facilitate incremental rewrites of an existing C++ library, making cross-language testing and validation very ergonomic; why C++ developers rarely take advantage of this (or even account for it as an option in their analysis of alternatives) is an exercise left to the reader.

> Rust was designed to facilitate incremental rewrites of an existing C++ library

Do you have a source for this claim? Rust is a fine language (though its advocates can be a bit belligerent sometimes). But, as a matter of fact, Rust was not designed for a easy interoperability with C++ or to make gradual rewrites easy.

One design constraint of Rust was to be able to be incrementally included in a large C++ codebase: Firefox.

It turns out that this kind of interop with C++ directly is extremely difficult, and so it isn’t super smooth right now. Interop with C was prioritized and you get zero overhead there. And various projects ease Rust <-> C++ via the C ABI.

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