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I understand the advantages of Rust over C or C++, but what are the advantages over OCaml, Standard ML, D and Go?

Rust's combination of no GC, unsafe escape hatch, and zero-cost C ABI FFI (both function calls and struct layouts) are among its biggest technically differentiating factors.

The FFI story seems to be overshadowed, but if you want to use things like Vulkan, DX12, etc... then C FFI performance becomes absolutely critical, and many languages are really bad at it.

I think the importance of selecting a C FFI is very much undersold.

You pretty much get interop with every major language for free. I've embedded Rust in Python, Java, C# and WASM/ASMJS pretty much with just that one feature alone.

Also makes the migration story really strong, which I think was largely driven by needing to be integrated into FireFox in a sane way.

I've gone further to say the freight train of an ecosystem behind and legacy effects of C mean any intended replacement should be fully compatible with its structure, calling conventions, etc. This lets anyone leverage existing C libraries or those in new language seemlessly. From there, the new stuff might all be done in better language with optional, incremental rewrites of older stuff.


Acide from GC, all of those apply to d.

Over Go: higher level code, more powerful ergonomic abstractions (generics, macros, etc), and of course the lack of runtime/GC.

Over OCaml/Standard ML: more control over performance. It's also imperative first rather than functional first, which isn't neccessarily an advantage, but it is to people coming from a imperative programmig background.

Over D: much more momentum behind the ecosystem.

Rust's borrowing system is pretty unique and allows for safe concurrency in a way that none of those languages can. Compared to Go in particular Rust brings a much more powerful type system as well.

The design goal of Rust is to have C++-like efficiency with all the benefits of modern programming language theory and practice, as well as some new innovations. In particular, Rust wants to address the two problems of templating/polymorphism/generics and mutability/sharing with zero efficiency or safety sacrifices. (I am not a Rust developer, that's just my impression.)

If you like OCaml/Haskell/etc but find yourself wishing you could make mutability and ownership more safe, or write very fast code more easily, and are willing to give up higher-order type system features for it, consider Rust.

Go is a very different language than Rust even though both superficially resemble C. If you're using Go because you want something C-like but better, consider Rust.

If I understand correctly, Go is the new C++ and/or Java, whereas Rust is the new C.

Not really. Rust is mainly "the new" C++ (and is also looking to encroach on C).

Go is more like (a better) PHP or Java on a webserver.

Go could be considered a modern C, in that it follow's C's spirit of simplicity and clarity at the expense of power and expressiveness, but it is often not used as a replacement of C for various reasons. One of Go's stated design goals was (and is) to achieve performance parity with C, but it falls short of reaching that goal in many cases.

With its type system and support for generics (in C++: templates), Rust has much more in common with C++ than it does with C.

> in that it follow's C's spirit of simplicity and clarity at the expense of power and expressiveness

Wow, I strongly feel the opposite about C. It is hardly simple or clear - understanding what your code will do after the compiler's done with it seems almost impossible, reasoning about runtime behavior similarly so. The complexity involved in managing memory, etc, is so significant.

But it is extremely powerful.

I see go as being extremely simple, but also very weak in terms for expressiveness, relying on the runtime for memory and concurrency management.

I agree that Rust has more in common with C++.

I was shooting for a simple answer, but perhaps some more clarification would be useful.

I describe C as "simple" in the sense that it's A) not a large language, by specification and B) somewhat by virtue of the former, there's generally a small range of possible implementations of any given problem (which helps C programs have "clarity"). Go is very C-like in that it also has both of these attributes, quite deliberately. C could be considered complex, however, by virtue of the amount of behavior that is unspecified/at the compiler's discretion. In that sense its safety often is difficult to reason about, but C programs themselves are generally easy to reason about. Go luckily doesn't have many opportunities for programs to be "complex" in that way.

C is "powerful" in the sense that it offers programmers deep control over memory. Given that, (effectively) anything that can be implemented in any other language can be implemented in C, with varying levels of difficulty. It isn't "powerful" from the language perspective itself — in terms of expressiveness or the features that it affords programmers — in the same way that C++ or Rust are "powerful".

A lot of the adjectives we use to describe languages aren't particularly well-defined, so some disagreement about them is almost a given. But hopefully that clarifies.

Yeah, that makes a lot of sense to me. Thanks.

No, it's more like Go is (not enough to be) new Python or node.js.

Go has very little in common with either of those languages except a GC. Go is statically typed, natively compiled, a good 10-100X faster, and it has great concurrency/parallelism stories. It also lacks classes and exceptions.

I meant the possible target audience. While their initial goal was to attract C++ engineers, eventually they attracted (some) python or node.js devs.

Ah, I understand and agree. Thanks for clarifying!

Funny, I feel the opposite, Go being more like C and Rust being more like C++; mostly due Go's strive for simplicity while Rust seems more comfortable embracing C++ level of complexity.

Rust enforces proper acquisition and releasing of resources, and that is very cool. For that it uses linear types, which is beyond what ML's type system can achieve. It allows rust to manage memory safely with no GC. The type system can show the compiler when to release resources. I think that can be done in C++ and maybe Haskell but Rust has it baked in.

Think about all the low level resource management: network ports, files, heap memory... That's what rust does better.

Check ATS for a ML-inspired language with some resource semantics closer to rust and stronger control and correctness primitives. http://www.ats-lang.org

Lower level, possible isolated unsafe code, more compilation checks, supported by Mozilla. More active and enthusiastic community than D, OCaml or Standard ML.

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