Comparing apples to orange rustaceans 29 Aug 2020
rust opinion

Never trust a developer who praises the purity or elegance of the C programming language. I find comparisons often made between Rust and C for “systems programming” to be one of my least favorite, and most disingenuous discussion topics among developers on the internet. It’s like comparing roller skates to an electric car. While they both can transport you from one place to another, only one of them is likely going to bring you safely to your destination.

Tweets like this one or blog posts like this one really help drive the point home that C is not what most people think it is. One of the common themes is “complexity.” It is absurd to talk about C’s simplicity compared to Rust’s complexity because C:

  • Doesn’t have a standard library
  • Doesn’t have any built in concurrency or parallelism primitives
  • Doesn’t have any concept of modularization.
  • Doesn’t offer type safety.

C isn’t actually one thing to begin with either. Depending on which revision of the specification and which compiler you use, a C program may not be compilable. Each compiler has a slightly different perspective on what the gaps, “undefined behavior” in what C is actually defined as, should mean in the real world.

Most of the worst security bugs are trivial to write in C. In order to “safely” write C, a significant amount of static analysis, developer chutzpah, and code review needs to be added into the development process.

C was invented 48 years ago.

As an industry we have learned and evolved so much in the way we think about safety, concurrency, and software development as a discipline in the last five decades. To me, adopting C for a new project is throwing all that away for misguided notions of purity and performance.

I considered offering platitudes about what C is good at, or where C belongs. Instead I’m going to take a hardline approach:

C is dangerous, inefficient, and has no place in modern development.

Don’t take this as “you should use Rust” (you should) but rather: you should not use C for anything new.