Why is Rust being used to replace parts of the JavaScript web ecosystem like minification (Terser), transpilation (Babel), formatting (Prettier), bundling (webpack), linting (ESLint), and more?
The GC in Go is fantastic IMO since it runs in a separate thread. I used it since 1.0 (switched our product from node.js), and dealt with all the the pain of an imprecise GC (fixed in 1.5?) and all the little improvements to arrive at it’s current state.
The main issues I have with it are pretty core to the language, unfortunately, such as:
interface{} is basically a void*, but since it’s a fat pointer, it can hold nil without itself being nil, which can happen by accident
runtime reflection is a bad habit, but it’s unfortunately really common
it’s really easy to deadlock by making stupid mistakes; if it had automatic unlocking based on scope (like Rust, or something like Python’s context managers), we could solve this, but defer just isn’t good enough
no destructors - with destructors, we could build a solution to deadlocks
Maybe they fixed some of those issues, idk, I haven’t used it for several years. I did use it for about 10 years though.
I assume you’re talking about runtime. AddCleanup()? That’s certainly nice, but it’s not the same as a destructor since it only runs at GC time. It’s useful for cleaning up data used by a shared library or something (e.g. something malloc’d by a C lib), but it only solves part of the problem.
I’m talking about scope guards. In Rust, here’s how you deal with mutexes:
{
letvalue = mutex.Lock();
... use value ...
// mutex.Unlock() automatically called
}
The closest thing in Go is defer():
mutex.Lock()
defer mutex.Unlock()
That works most of the time, but it doesn’t handle more complex use cases, like selectively unlocking a mutex early while still guaranteeing it eventually gets unlocked.
Rust fixes this with the Drop trait, so basically I can drop something early conditionally, but it’ll get dropped automatically when going out of scope. For example:
Without the last line, this prints c, b, a, i.e. stack order. With the last line, it instead prints b, c, a, because I drop b early.
This is incredibly useful when dealing with complex logic, especially with mutexes, because it allows you to cleanly and correctly handle edge cases. Things are dropped at block scope too, giving even more control of semantically releasing things like locks.
That said, 1.24 added WASM, which is really cool, so thanks for encouraging me to look at the release notes.
Thanks for taking the time to explain it. Indeed the new runtime method does not guarantee when the resource will be cleaned, so something like that Drop trait would be quite useful
The GC in Go is fantastic IMO since it runs in a separate thread. I used it since 1.0 (switched our product from node.js), and dealt with all the the pain of an imprecise GC (fixed in 1.5?) and all the little improvements to arrive at it’s current state.
The main issues I have with it are pretty core to the language, unfortunately, such as:
interface{}is basically avoid*, but since it’s a fat pointer, it can holdnilwithout itself beingnil, which can happen by accidentdeferjust isn’t good enoughMaybe they fixed some of those issues, idk, I haven’t used it for several years. I did use it for about 10 years though.
Not sure if that’s what you are referring to as destructors, but they added a new way to have code run at resource collection in go 1.24
I assume you’re talking about
runtime. AddCleanup()? That’s certainly nice, but it’s not the same as a destructor since it only runs at GC time. It’s useful for cleaning up data used by a shared library or something (e.g. something malloc’d by a C lib), but it only solves part of the problem.I’m talking about scope guards. In Rust, here’s how you deal with mutexes:
{ let value = mutex.Lock(); ... use value ... // mutex.Unlock() automatically called }The closest thing in Go is
defer():mutex.Lock() defer mutex.Unlock()That works most of the time, but it doesn’t handle more complex use cases, like selectively unlocking a mutex early while still guaranteeing it eventually gets unlocked.
Rust fixes this with the
Droptrait, so basically I can drop something early conditionally, but it’ll get dropped automatically when going out of scope. For example:struct A(String); impl Drop for A { fn drop(&mut self) { println!("dropping {}", self.0) } } fn main() { let a = A("a".into()); let b = A("b".into()); let c = A("c".into()); drop(b); }Without the last line, this prints c, b, a, i.e. stack order. With the last line, it instead prints b, c, a, because I drop b early.
This is incredibly useful when dealing with complex logic, especially with mutexes, because it allows you to cleanly and correctly handle edge cases. Things are dropped at block scope too, giving even more control of semantically releasing things like locks.
That said, 1.24 added WASM, which is really cool, so thanks for encouraging me to look at the release notes.
Thanks for taking the time to explain it. Indeed the new runtime method does not guarantee when the resource will be cleaned, so something like that Drop trait would be quite useful