I’m not sold on the idea of “imperative programming without any shared mutable state at all”. Maybe I just can’t accurately imagine what that would look like in practice.
Neither.
for tasks that are not inherently unsuited to Rust’s current state
Curious where you draw the line on this.
This is the single “deepest” lesson that I feel like I’ve learned about Rust so far. Lifetimes, stumbled upon while trying to avoid (runtime) garbage collection, are in fact a more general tool for delimiting behavior/causality in programs.
Interesting you use the word “causality” there … do you have anything in particular in mind or are you generally thinking about trying to nail down what the cause of a bug may be?
I liked the phrase from the article (which you quote): you never need to worry about “spooky action at a distance.” (emphasis mine).
for me this mostly comes down to the state of the ecosystem (game dev with godot, websites in js are 2 cases where I’m not really interested in using rust)
but for example when I want to just solve a problem and the input size won’t cause a naive approach to run very slow, I’ll probably grab python instead
or if the solution is something hyper dynamic (a la dynamic programming), it would probably be simpler in ocaml or haskell or f# - ie something more “truly” immutable so that you don’t have to worry about data lifetimes or manual memory management (and it’s generally very cheap and elegant to push & pop from stacks and queues in such languages)
re: causality and “spooky action at a difference”
It’s more:
mutable vs immutable references mean any mutable access must happen before or after all other accesses [to the same data]
any access to a moved value must happen before the move itself
So ownership effectively imposes a certain causal order on your code, that emerges from which behavior uses/accesses which data. In many aspects it’s way too hazy to act as a “proper” causal order, but I often find it easier to write code that passes the borrow checker on the first try when I try to organize my code according to this notion.
I would almost describe my mental image as if there were compiler-enforced RWLocks on all mutable references, and as if all moves are somehow telling the os to change which virtual memory address is mapped onto the (moved) data (without actually copying the data into a different part of memory).
I’d kinda developed the same attitude but never really thought about it in terms of “causality” as you put it. Instead I had more of a “clean code” or “efficiency” framing, but I like yours much better.
Neither.
Curious where you draw the line on this.
Interesting you use the word “causality” there … do you have anything in particular in mind or are you generally thinking about trying to nail down what the cause of a bug may be? I liked the phrase from the article (which you quote): you never need to worry about “spooky action at a distance.” (emphasis mine).
for me this mostly comes down to the state of the ecosystem (game dev with godot, websites in js are 2 cases where I’m not really interested in using rust) but for example when I want to just solve a problem and the input size won’t cause a naive approach to run very slow, I’ll probably grab python instead or if the solution is something hyper dynamic (a la dynamic programming), it would probably be simpler in ocaml or haskell or f# - ie something more “truly” immutable so that you don’t have to worry about data lifetimes or manual memory management (and it’s generally very cheap and elegant to push & pop from stacks and queues in such languages)
re: causality and “spooky action at a difference”
It’s more:
mutable vs immutable references mean any mutable access must happen before or after all other accesses [to the same data]
any access to a moved value must happen before the move itself
So ownership effectively imposes a certain causal order on your code, that emerges from which behavior uses/accesses which data. In many aspects it’s way too hazy to act as a “proper” causal order, but I often find it easier to write code that passes the borrow checker on the first try when I try to organize my code according to this notion.
I would almost describe my mental image as if there were compiler-enforced RWLocks on all mutable references, and as if all moves are somehow telling the os to change which virtual memory address is mapped onto the (moved) data (without actually copying the data into a different part of memory).
Yea nice.
I’d kinda developed the same attitude but never really thought about it in terms of “causality” as you put it. Instead I had more of a “clean code” or “efficiency” framing, but I like yours much better.