[Rusky]

"Systems language" usually refers to lower-level programming. For example: an OS kernel or its drivers where you're poking at hardware and need control over memory layout, a library to be called from many other languages that thus needs to avoid a large runtime and garbage collector, or high-performance infrastructure like web servers or game engines. Generally things you've had to use C or C++ for, in the past.

Go is sometimes called a systems language, but in a much narrower sense than Rust. For example, it is garbage collected and has a runtime, so it's not great at being FFI'd into. It seems to be quite useful for distributed applications.

Rust, on the other hand, is closer to C++ in that it has no real runtime and no GC. On top of that, it brings compile-time memory safety and lots of other modern features to systems programming. One of its biggest applications is making Firefox safer and faster as part of the Quantum project (https://wiki.mozilla.org/Quantum).

Part of why Rust is more symbol-heavy than Python or Javascript is it has to express things in more detail, giving you the control required to do systems programming. So it's not necessarily a direct competitor to JS, since it can work in areas JS simply can't.

In some ways, though, that can make it more productive- static typing is like compiler-enforced documentation and tests, making it easier to keep track of a large codebase.

[slowmovintarget]

>> Rust, on the other hand, is closer to C++ in that it has no real runtime and no GC. On top of that, it brings compile-time memory safety and lots of other modern features to systems programming.

I think that's it in a nutshell.

I want to write a program in a language that allows modern programming construction... Cool: Python, Ruby, JavaScript (ES 6+), Haskell, Elixir

The language must be fast... OK, so maybe Java or C#?

I need to control the response times and can't have GC pauses. It needs to be really fast... Assembly!

Stop... OK, OK, you're kind of stuck with C or C++.

Sigh. I want a modern language that compiles to bare metal, doggone it. What should I do?

This is what Rust is. Memory safety without GC, and a modern language without an interpreter or runtime. Plus all the package management/build tool/library ecosystems that all those 1990s languages have. (Would you believe that Java, Ruby, and Python are all more than 20 years old and that Java is the youngest of the three?!?)