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A half-hour to learn Rust

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Re: A half-hour to learn Rust

#11

Post by chamakits »

mrlonglong wrote: post #5

It only took me a couple of hours to port one of my old C programs, an utility to produce a hexadecimal and ASCII dump to Rust. The Borrow checker didn't even faze me. All I needed was plenty of Google-fu and my coding skills. JetBrains CLion and git are also very useful tools.

I had a similar experience porting a relatively straightforward and simple CLI utility I had written in C.

Having said that, when I've faced real challenges with Rust (and the borrow checker) it's been with bigger longer running applications, like a webapp, or a long running service.

I have no doubt part of that comes I have a stronger background in garbage collected languages, so my mindset when developing larger applications is in that mode. I'm sure with enough practice I'd get it, but there were many things that I just couldn't replicate one to one in Rust. Not that they weren't possible, but they were just different enough that I couldn't figure it out without being more comfortable in understanding the language, and I just haven't dedicated the time needed to it.

Will likely go back to it at some point, as it is an interesting approach to programming, with lots of upsides.

Re: A half-hour to learn Rust

#12

Post by red2awn »

mcsalgado wrote: post #6

In the 9th code snippet that's not an example of variable shadowing, it's just variable reassignment. Shadowing involves variable assignments in different scopes. https://en.wikipedia.org/wiki/Variable_shadowing edit: I should've called it "variable redefinition" or something like that I guess, my mistake. Reassignment is definitely not the correct terminology for this. Still, it's not shadowing because the new bindi…

There is literally a Rust example in your wiki link saying that this is shadowing. You can even redefine the variable to have a different type, how can this be reassignment.

Re: A half-hour to learn Rust

#13

Post by kd5bjo »

mcsalgado wrote: post #6

In the 9th code snippet that's not an example of variable shadowing, it's just variable reassignment. Shadowing involves variable assignments in different scopes. https://en.wikipedia.org/wiki/Variable_shadowing edit: I should've called it "variable redefinition" or something like that I guess, my mistake. Reassignment is definitely not the correct terminology for this. Still, it's not shadowing because the new bindi…

No, it really is shadowing. The second `let` allocates a new memory location in the activation record; all future mentions of the variable name will refer to the new location. The old location still exists, and may have references to it already; references that will continue pointing at the old allocation and will not see anything that happens to the new one. If the old value has a `Drop` implementation, it will run after the second allocation’s `drop()`. The two `let` bindings can even have completely different types.

Re: A half-hour to learn Rust

#15

Post by Animats »

That is the best article on Rust I've ever seen. Better than the Rust book. I've been saying that Rust needed a book that wasn't written by the designers of the language, who are too close to it. Now we have one.

Re: A half-hour to learn Rust

#16

Post by powersnail »

mcsalgado wrote: post #6

In the 9th code snippet that's not an example of variable shadowing, it's just variable reassignment. Shadowing involves variable assignments in different scopes. https://en.wikipedia.org/wiki/Variable_shadowing edit: I should've called it "variable redefinition" or something like that I guess, my mistake. Reassignment is definitely not the correct terminology for this. Still, it's not shadowing because the new bindi…

Isn't variable reassignment a special case of variable shadowing, where the new scope closes at the same place as the parent scope?

Re: A half-hour to learn Rust

#19

Post by tgv »

Animats wrote: post #15

That is the best article on Rust I've ever seen. Better than the Rust book. I've been saying that Rust needed a book that wasn't written by the designers of the language, who are too close to it. Now we have one.

But it only covers the very basics. Disclaimer: I've only scrolled through it, but the code snippets are all small. It does show an admirable amount of Rust's syntax, but it's not very discoverable, whereas the book is reasonably well structured (although not for novices, who have forgotten a specific term). The link also doesn't deal with larger programs: there's not an Rc on the page, let alone something like an Arena and unsafe code, and it's really necessary for complex programs.

So, IMO: not better than the Rust book. It gives a first glance of Rust, something to accustom the eyes to a different syntax, but sidesteps the difficult bits, which can make transitioning so frustrating.

Re: A half-hour to learn Rust

#20

Post by mrlonglong »

chamakits wrote: post #11
mrlonglong wrote: post #5

It only took me a couple of hours to port one of my old C programs, an utility to produce a hexadecimal and ASCII dump to Rust. The Borrow checker didn't even faze me. All I needed was plenty of Google-fu and my coding skills. JetBrains CLion and git are also very useful tools.

I had a similar experience porting a relatively straightforward and simple CLI utility I had written in C. Having said that, when I've faced real challenges with Rust (and the borrow checker) it's been with bigger longer running applications, like a webapp, or a long running service. I have no doubt part of that comes I have a stronger background in garbage collected languages, so my mindset when developing larger ap…

My biggest issue was trying to print the contents of u8 as a character. In the end this was actually as simple as writing print!("{}", line[i] as char), no print specifiers needed.

I may do another more complicated port soon. I love CLion.

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