Why Go and Rust are not competitors

This is a short blog post explaining why I believe that Go and Rust are not competitors.

Why people think Rust and Go are competitors

To explain why I think Rust and Go are not competitors, I want to to lay out the reasons why I think the question is being asked in the first place.

  • Rust and Go were announced around the same time. Go was conceived in 2007 and became public in November of 2009. Rust appeared a few months later in 2010, although Graydon hints that Rust may have been conceived much earlier. In either case, both languages have a distinguished pedigree of influential predecessors. In the case of Go, Hoare’s CSP, Alef, and Pike’s Newsqueak. Rust is viewed as an extension of the ML family of languages.
  • Rust and Go are both touted as memory safe. While this statement is absolutely true, both languages will not tolerate unsafe memory access, what is more important is that the world will not tolerate any new language which is not memory safe. It just so happens that Go and Rust are the first two languages to emerge after decades of evidence that in the real world, programmers as a whole, cannot safely manage memory manually.
  • Both are young languages, Go achieving 1.0 status in 2012, and Rust earlier this year, implying ambition and upward mobility towards a space occupied by incumbent languages.

These are the arguments that I see used to justify why Rust and Go are competitors. Laying them out like this, it’s hard to find them compelling, indeed they appear circumstantial.

Why I think rust and Go are not competitors

So, why do I think that Go and Rust are not competitors ?

  • Rust is focused on “free of charge” abstractions. If this sounds familiar, this has been the catch cry for C++ for decades. As a language which defers many low level actions to its runtime, Go sacrifices some performance for its goals of simplicity and orthogonality.
  • Rust is designed for interoperability with C; Rust code is expected to be embedded in other large programs which follow the C calling convention. Go does allow some interoperability through cgo, but this is clearly not the expected way that Go programs will be written.
  • Go is focused on concurrency as a first class concept. That is not to say you cannot find aspects of Go’s actor oriented concurrency in Rust, but it is left as an exercise to the programmer.
  • Go is focused on programmer productivity, across the whole software development lifecycle. Rust, as a front end to LLVM, punts on many of those decision.

Rust and Go are not competitors

Go is focused on making large teams of programmers efficient, though rigid application of simplicity — ideas which are not simple or lead to non orthogonal corner cases are rejected.

Rust is focused on a class of programs which cannot tolerate unsafe memory access (neither can Go, I don’t think there is any appetite for a new unsafe programming languages) or runtime overhead — ideas which are unsafe, or come with overhead, are rejected or at least pushed out of the core language.

Rust competes for mindshare with C++ and D for programmers who are prepared to accept more complex syntax and semantics (and presumably higher readability costs) in return for the maximum possible performance. For example, micro controllers, AAA game engines, and web rendering engines.

Go competes for mindshare in the post 2006 Internet 2.0 generation of companies who have outgrown languages like Ruby, Python, and Node.js (v8) and have lost patience with the high deployment costs of JVM based languages.