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> it doesn't mean there aren't now logic errors in the code which would do something just as bad Yes, it does. He wants to have immutable access to some data,

> it doesn't mean there aren't now logic errors in the code which would do something just as bad Yes, it does. He wants to have immutable access to some data, the Rust borrow checker's rules provide certainty that the data is not deleted or mutated while his code is accessing it. What could happen that is "just as bad"? Data being referenced cannot be changed.

tatterdemalion 11y ago
I think an important thing to make sense of this is that Rust doesn't guarantee that what Manishearth did will work! Just that if it doesn't work, the code will not compile. It could have been the case that this vector was mutated or deleted at some point during the lifetime of his new struct; in that case, his code would not have compiled.
berkut 11y ago
In this case it does. I was more talking about the overall not caring theme. I'd hope that's only because they know the code so can make those sort of assumptions. Are you saying Rust can find and prevent at compile time logic errors as well?
- tatterdemalion 11y ago
  You "don't care," I'm sure, about all kinds of things when you're programming - depending on what level you're at. Unless you're drawing up CPU schematics, there is something that you have abstracted away as no longer your concern. Rust allows you to not care about more things than C/C++ despite compiling to a comparable binary. In particular, Rust makes refactoring and extending a code base much more care-free than many other languages (including high level languages) because of the strong type and memory safety guarantees of its semantics. EDIT (re: your edit) - No one said anything about preventing arbitrary logic errors, just that what Manishearth did will not introduce logic errors because of Rust's guarantees. This could not be the data that Manishearth wants, but the compiler guarantees that Manishearth cannot change the data or delete the data and that the data is not changed or deleted while he is referencing it. That is what is so great.
  - berkut 11y ago
    What edit? My second comment? That was my original point regarding logic errors and not caring - yes, it may well be that Rust gives you much more confidence that you don't do invalid/wrong things. But that excludes logic errors (it may well reduce the possibility of logic errors, but it doesn't prevent them), and there's still room in large code bases for things to break even with very good static type checking.
- kibwen 11y ago
  > I was more talking about the overall not caring theme. Not having to care about memory management gives me more mental energy for caring about the other parts of my program. The lack of anxiety about memory semantics is one of the most compelling reasons for me to use Rust. > Are you saying Rust can find and prevent at compile > time logic errors as well? In some ways it certainly can. Its type system guarantees at compile time that your code cannot contain data races, making massive concurrency and parallelism much easier to introduce. You can also push the type system to do things like check units for you, such as is done in Servo: https://blog.mozilla.org/research/2014/06/23/static-checking-of-units-in-servo/ https://blog.mozilla.org/research/2014/06/23/static-checking...

tatterdemalion 11y ago

I think an important thing to make sense of this is that Rust doesn't guarantee that what Manishearth did will work! Just that if it doesn't work, the code will not compile. It could have been the case that this vector was mutated or deleted at some point during the lifetime of his new struct; in that case, his code would not have compiled.

berkut 11y ago

In this case it does. I was more talking about the overall not caring theme. I'd hope that's only because they know the code so can make those sort of assumptions. Are you saying Rust can find and prevent at compile time logic errors as well?

tatterdemalion 11y ago
You "don't care," I'm sure, about all kinds of things when you're programming - depending on what level you're at. Unless you're drawing up CPU schematics, there is something that you have abstracted away as no longer your concern. Rust allows you to not care about more things than C/C++ despite compiling to a comparable binary. In particular, Rust makes refactoring and extending a code base much more care-free than many other languages (including high level languages) because of the strong type and memory safety guarantees of its semantics. EDIT (re: your edit) - No one said anything about preventing arbitrary logic errors, just that what Manishearth did will not introduce logic errors because of Rust's guarantees. This could not be the data that Manishearth wants, but the compiler guarantees that Manishearth cannot change the data or delete the data and that the data is not changed or deleted while he is referencing it. That is what is so great.
- berkut 11y ago
  What edit? My second comment? That was my original point regarding logic errors and not caring - yes, it may well be that Rust gives you much more confidence that you don't do invalid/wrong things. But that excludes logic errors (it may well reduce the possibility of logic errors, but it doesn't prevent them), and there's still room in large code bases for things to break even with very good static type checking.
kibwen 11y ago
> I was more talking about the overall not caring theme. Not having to care about memory management gives me more mental energy for caring about the other parts of my program. The lack of anxiety about memory semantics is one of the most compelling reasons for me to use Rust. > Are you saying Rust can find and prevent at compile > time logic errors as well? In some ways it certainly can. Its type system guarantees at compile time that your code cannot contain data races, making massive concurrency and parallelism much easier to introduce. You can also push the type system to do things like check units for you, such as is done in Servo: https://blog.mozilla.org/research/2014/06/23/static-checking-of-units-in-servo/ https://blog.mozilla.org/research/2014/06/23/static-checking...