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Rust doesn't have a runtime. That's part of its awesomeness. That's why it can target microcontrollers. You're probably used to languages with garbage collec

Rust doesn't have a runtime. That's part of its awesomeness. That's why it can target microcontrollers. You're probably used to languages with garbage collectors. Having garbage collection forces you to have a "runtime" since that's where the GC code goes. Then more and more stuff accretes onto this unavoidable runtime, and before you know it you're writing Java code...

olliej 6y ago
Um, rust does have a runtime, that's why you don't need to include packages for strings, refcounting, allocation, etc. Anything that has a language keyword should have a default implementation in that runtime, and much like box, ?, !, etc async and await are both language features that I shouldn't need to include from outside of the runtime.
- ibraheemdev 6y ago
  What the OP is probably referring to is that Rust does not have a runtime in the typical sense used by languages such as Java. Rust does have a runtime, as all non-assembly languages do, but it is very very small. Languages with minimal runtimes like C or Rust are commonly referred to as having "no runtime".
- GolDDranks 6y ago
  Those are all pay-as-you go features; in my mind I associate runtime with a single, constant-ish initialization cost, plus possibly some background processing or inserted hooks that do janitor work for you. Rust doesn't have a runtime in that sense.
- octoberfranklin 6y ago
  > you don't need to include packages for strings, refcounting, allocation, etc. Oh, but you do! These are in std::str, std::rc, and std::alloc, respectively. You're absolutely able to choose not to include these packages, with #![no_std]. That's how rust is able to target platforms like 8-bit microcontrollers with 16kbytes of RAM. https://rust-embedded.github.io/book/intro/no-std.html https://rust-embedded.github.io/book/intro/no-std.html
- mratsim 6y ago
  I think you are confusing a standard library with a runtime. A runtime is something you need to start before being able to use a language (typically a garbage collector, an event loop, a threadpool or a VM)

olliej 6y ago

Um, rust does have a runtime, that's why you don't need to include packages for strings, refcounting, allocation, etc. Anything that has a language keyword should have a default implementation in that runtime, and much like box, ?, !, etc async and await are both language features that I shouldn't need to include from outside of the runtime.

ibraheemdev 6y ago
What the OP is probably referring to is that Rust does not have a runtime in the typical sense used by languages such as Java. Rust does have a runtime, as all non-assembly languages do, but it is very very small. Languages with minimal runtimes like C or Rust are commonly referred to as having "no runtime".
GolDDranks 6y ago
Those are all pay-as-you go features; in my mind I associate runtime with a single, constant-ish initialization cost, plus possibly some background processing or inserted hooks that do janitor work for you. Rust doesn't have a runtime in that sense.
octoberfranklin 6y ago
> you don't need to include packages for strings, refcounting, allocation, etc. Oh, but you do! These are in std::str, std::rc, and std::alloc, respectively. You're absolutely able to choose not to include these packages, with #![no_std]. That's how rust is able to target platforms like 8-bit microcontrollers with 16kbytes of RAM. https://rust-embedded.github.io/book/intro/no-std.html https://rust-embedded.github.io/book/intro/no-std.html
mratsim 6y ago
I think you are confusing a standard library with a runtime. A runtime is something you need to start before being able to use a language (typically a garbage collector, an event loop, a threadpool or a VM)