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I agree that it must be possible to use the language in a very low overhead, literal way. That's not most use, I think. Most applications can tolerate exception

I agree that it must be possible to use the language in a very low overhead, literal way. That's not most use, I think. Most applications can tolerate exceptions, so stdlib should have used exceptions to report errors. The people who can't tolerate exceptions are the same ones who want precise machine control and who probably don't want stdlib either. If exceptions were the only way to report errors in stdlib, stdlib wouldn't have had to panic on errors --- or, rather, users would have come to expect these panics instead of treating them as a fatal, anomalous condition. The trade off seems wrong here --- you should be able to support stdlib and exceptions for clarity or !stdlib and !exceptions for full control, but I don't see a big case for stdlib and ! exceptions, but the way Rust is designed, everyone pays for the stdlib and !exceptions model. (And they have to care about exceptions anyway, but can't rely on them.) I think Rust's error handling is very poor design. I regret that this opinion coming across makes it difficult to have a conversation.

burntsushi 10y ago
If your only error handling mechanism is exceptions and you disable exceptions because you can't bare the cost, then what are you left with? > The people who can't tolerate exceptions are the same ones who want precise machine control and who probably don't want stdlib either. I don't agree. Just because I don't want to pay for exceptions doesn't mean I don't want, say, convenient platform abstractions over file systems or I/O. > I regret that this opinion The opinion that you don't like Rust's error handling isn't the problem. It's all of the insinuations you're making about the people who worked on it. You paint a picture of carelessness and irrationality, but that couldn't be further from the truth. The other problem is that exceptions vs. error values---aside from the performance or implementation implications---is a debate unto itself without a clear answer, but you pretend as if it's a solved problem and that your view couldn't possibly be wrong. On the other hand, I'm trying to sit here and say that there are trade offs, but you don't want to acknowledge them.
- quotemstr 10y ago
  What is reporting the errors? In a standalone environment, in which you're left with the core language, anything that reports errors is something you can define, and you can define that component to use error codes, just as we would in C. It feels odd to want exact control over the error handling abstraction but want to use Rust's convenient IO abstraction. Performance either matters or it doesn't. > debate unto itself without a clear answer, but you pretend as if it's a solved problem and that your view couldn't possibly be wrong This debate was settled: we started out with error codes. We saw a generation of languages with exceptions --- Java, C++, CL with its condition system, Python, etc. arise in reaction to the problems with error codes. The current movement away from exceptions, which I think started with Go, feels like backsliding, especially because most of the justifications for error code primacy that I see either ignore the actual (instead of mythologized) costs of exceptions or claim that exceptional code is a hardship inconsistent with my experience. Now, it's possible that we should think of exceptions as just a failed experiment, but that view isn't consistent with the extreme utility I've seen in exception systems. Exceptions are so useful that people build them out of longjmp! Anyway, it's frustrating that because Rust tried to solve simultaneously for ergonomics, exception freedom, and a rich standard library, it ended up in a position of having to abort on OOM. (I realize that there are more options these days.) Still, exceptions in stdlib with an option for an exception free standalone system feels like the more appropriate trade-off. I understand that there are trade-offs everywhere, but this observation doesn't mean that I have to excuse what I see as very bad trade-offs.
  - burntsushi 10y ago
    > It feels odd to want exact control over the error handling abstraction but want to use Rust's convenient IO abstraction. Performance either matters or it doesn't. This doesn't make any sense. What are the performance costs of doing I/O in Rust using `std::io`? If there are none, why would I want to give it up? AFAIK, the only reason to give up `std::io` is if your platform isn't supported by `std`. > it's possible that we should think of exceptions as just a failed experiment Who said that? Why does one way have to be right? There are trade offs! I'm sure you can find plenty of articles on the Internet that discuss exceptions vs. values. There are plenty of reasonable arguments on both sides. > This debate was settled OK, that's enough. I won't waste any more of my time with someone who is so certain of themselves.

burntsushi 10y ago

If your only error handling mechanism is exceptions and you disable exceptions because you can't bare the cost, then what are you left with? > The people who can't tolerate exceptions are the same ones who want precise machine control and who probably don't want stdlib either. I don't agree. Just because I don't want to pay for exceptions doesn't mean I don't want, say, convenient platform abstractions over file systems or I/O. > I regret that this opinion The opinion that you don't like Rust's error handling isn't the problem. It's all of the insinuations you're making about the people who worked on it. You paint a picture of carelessness and irrationality, but that couldn't be further from the truth. The other problem is that exceptions vs. error values---aside from the performance or implementation implications---is a debate unto itself without a clear answer, but you pretend as if it's a solved problem and that your view couldn't possibly be wrong. On the other hand, I'm trying to sit here and say that there are trade offs, but you don't want to acknowledge them.

quotemstr 10y ago
What is reporting the errors? In a standalone environment, in which you're left with the core language, anything that reports errors is something you can define, and you can define that component to use error codes, just as we would in C. It feels odd to want exact control over the error handling abstraction but want to use Rust's convenient IO abstraction. Performance either matters or it doesn't. > debate unto itself without a clear answer, but you pretend as if it's a solved problem and that your view couldn't possibly be wrong This debate was settled: we started out with error codes. We saw a generation of languages with exceptions --- Java, C++, CL with its condition system, Python, etc. arise in reaction to the problems with error codes. The current movement away from exceptions, which I think started with Go, feels like backsliding, especially because most of the justifications for error code primacy that I see either ignore the actual (instead of mythologized) costs of exceptions or claim that exceptional code is a hardship inconsistent with my experience. Now, it's possible that we should think of exceptions as just a failed experiment, but that view isn't consistent with the extreme utility I've seen in exception systems. Exceptions are so useful that people build them out of longjmp! Anyway, it's frustrating that because Rust tried to solve simultaneously for ergonomics, exception freedom, and a rich standard library, it ended up in a position of having to abort on OOM. (I realize that there are more options these days.) Still, exceptions in stdlib with an option for an exception free standalone system feels like the more appropriate trade-off. I understand that there are trade-offs everywhere, but this observation doesn't mean that I have to excuse what I see as very bad trade-offs.
- burntsushi 10y ago
  > It feels odd to want exact control over the error handling abstraction but want to use Rust's convenient IO abstraction. Performance either matters or it doesn't. This doesn't make any sense. What are the performance costs of doing I/O in Rust using `std::io`? If there are none, why would I want to give it up? AFAIK, the only reason to give up `std::io` is if your platform isn't supported by `std`. > it's possible that we should think of exceptions as just a failed experiment Who said that? Why does one way have to be right? There are trade offs! I'm sure you can find plenty of articles on the Internet that discuss exceptions vs. values. There are plenty of reasonable arguments on both sides. > This debate was settled OK, that's enough. I won't waste any more of my time with someone who is so certain of themselves.