proposal VS thiserror

I know they implemented an optimization back in go 1.13. Not sure if that will help.

https://github.com/golang/proposal/blob/master/design/34481-...

the most basic example was the declined proposal https://github.com/golang/proposal/blob/master/design/32437-...

Some people didn't like the "try" keyword it reminded them too much of exceptions, some people didn't like that they couldnt see a return inline (which was the purpose of the proposal in the first place).

it's not that there are no solutions. the main problem is the go team's insistence to have "one true way" (tm) of doing something and unfortunately this gap between people who want to see every return inline and people who want to see the clean solution separate from the error handling is not something that can be bridged by technical means. the only solution is to implement both ways and lets see which one wins.

The conclusion is pretty weird to me.

Go does rely on monomorphization for generics, just like C++ and Rust. The only difference is that this is an implementation detail, so Go can group multiple monomorphizations without worrying about anything else [1]. This form of hybrid monomorphization is being increasingly common, GHC does that and Rust is also trying to do so [2], so nothing special for Go here.

On the other hand, explaining variance as a lifted polymorphism is---while not incorrect per se---also weird in part because a lack of variance is at worst just an annoyance. You can always make an adopter to unify heterogeneous types. Rust calls it `Box`, Go happens to call it an interface type instead. Both languages even do not allow heterogeneous concrete (or runtime) types in a single slice! So variance has no use in both languages because no concrete types are eligible for variance anyway.

I think the conclusion got weird because the term "subtyping" is being misused. Subtyping, in the broadest sense, is just a non-trivial type relation. Many languages thus have a multiple notion of subtyping, often (almost) identical to each other but sometimes not. Go in particular has a lot of them, and even some relation like "T implements U" is a straightforward record subtyping. It is no surprise that the non-uniform value representation has the largest influence, and only monomorphization schemes and hetero-to-homogeneous adapters vary in this particular group.

[1] https://github.com/golang/proposal/blob/master/design/generi...

[2] https://rust-lang.github.io/compiler-team/working-groups/pol...

https://github.com/golang/proposal/blob/master/design/generi...

Go Team wanted generics since the start. It was always a problem implementing them without severely hurting compile time and creating compilation bloat. Rust chose to ignore this problem, by relying on LLVM backend for optimizations and dead code elimination.

Hold up, did the members actually push this forward or was support just often memed about and suddenly this proposal was made: https://github.com/golang/proposal/blob/master/design/43651-type-parameters.md

As far as I can tell, the consensus for generics was "it will happen, but we really want to get this right, and it's taking time."

I know some people did the knee-jerk attacks like "Go sucks, it should have had generics long ago" or "Go is fine, it doesn't need generics". I don't think we ever needed to take those attitudes seriously.

> Will error handling be overhauled or not?

Error handling is a thorny issue. It's the biggest complaint people have about Go, but I don't think that exceptions are obviously better, and the discriminated unions that power errors in Rust and some other languages are conspicuously absent from Go. So you end up with a bunch of different proposals for Go error handling that are either too radical or little more than syntactic sugar. The syntactic sugar proposals leave much to be desired. It looks like people are slowly grinding through these proposals until one is found with the right balance to it.

I honestly don't know what kind of changes to error handling would appear in Go 2 if/when it lands, and I think the only reasonable answer right now is "wait and find out". You can see a more reasonable proposal here:

https://github.com/golang/proposal/blob/master/design/go2dra...

Characterizing it as a "lack of vision" does not seem fair here--I started using Rust back in the days when boxed pointers had ~ on them, and it seemed like it took Rust a lot of iterations to get to the current design. Which is fine. I am also never quite sure what is going to get added to future versions of C#.

I am also not quite sure why Go gets so much hate on Hacker News--as far as I can tell, people have more or less given up on criticizing Java and C# (it's not like they've ossified), and C++ is enough of a dumpster fire that it seems gauche to point it out.

There will almost certainly not be a Go 2 in that sense. There is a Go 2 transition doc which extensively discusses what "Go 2" means. The conclusion is

As it says on that page - those were not proposals. They were draft ideas to get feedback on. You can see the list of proposals in this repository: https://github.com/golang/proposal

Inspired by this blog post I just added an `#[implicit]` field feature to the `thiserror` crate. It makes it easy to automatically annotate errors with things like code location (per this blog post), a timestamp, or a backtrace without requiring further modifications to the thiserror crate. I'm hoping that dtolnay will consider it. You can find my PR here: https://github.com/dtolnay/thiserror/pull/402

We can utilize third-party libraries to simplify the code above. For example thiserror (https://github.com/dtolnay/thiserror) provides convenien derive macro for Error trait:

thiserror crate makes it easy to do so using macros on CliError enum.

Depending on your use case, thiserror and/or anyhow.

What is the benefit of splitting a proc-macro crate into (usually) two crates, proc_macro_crate and proc_macro_crate_impl? Why not just have one crate? Does it offer any benefits to to overall compilation times? An example of this can be seen in the thiserror crate where there's a thiserror and thiserror_impl crate.

You might want to use thiserror to generate implementation for Error and Display.

thiserror for my error types.

thiserror - https://crates.io/crates/thiserror

I dont think you realize how ridiculous this comment is. Youre comparing 10 lines of Go, with 200 of Rust:

https://github.com/dtolnay/thiserror/blob/master/src/lib.rs