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but having all those things go would become another C++ with a different syntax. I like the direction Go is going of "there are no options to choose", like unc

but having all those things go would become another C++ with a different syntax. I like the direction Go is going of "there are no options to choose", like unconfigurable fmt, or the fact that there is no way to create "exotic" implementations. However, generics would be my number #1 on the list of "maybe let's add that". Would be nice to have less "interface {}" in reusable libraries. Exceptions would be probably second, but that would come with some sort of runtime cost. With them Go would start to drift towards "generic programming language".

pcwalton 10y ago
Exceptions don't have any runtime costs beyond those which Go is already paying by mandating unwinding. In fact, C++-style exceptions are strictly less expensive in the non-exceptional case than defer, because of defer's dynamic semantics. Go's semantics require a slower exceptional control flow scheme than almost any other language I'm aware of, including dynamic ones like JavaScript.
- duaneb 10y ago
  IIRC the idea is that the conceptual overhead of exceptions is much larger than the runtime cost, hence the minimal syntax/runtime support beyond defer (which is easy to follow, if hard to implement efficiently). I am not so sure I would agree with this, but I don't use go enough to have a firm opinion myself.
  - pcwalton 10y ago
    Try/catch/finally is simpler than panic/recover/defer both conceptually and in implementation, due to the statically, lexically-scoped semantics.
    - enneff 10y ago
      As you probably already know, panic/recover/defer are not supposed to be used in the same way as try/catch/finally. They're different features for different purposes. If you want error handling in Go, use error values.
      - pcwalton 10y ago
        Sure. Panic, recover, and defer are in the language, though, and are more complex than exceptions regardless of how they're intended to be used.
    - duaneb 10y ago
      If recover is used in a file you never read, is its complexity relevant?
      - enneff 10y ago
        I think what's happening here is pcwalton is a language implementer, so when you talk about 'conceptual complexity' he thinks about how the feature is specified, whereas you or I think about how the users of the feature think about and use it. We're all talking past each other a bit, I think.
        duaneb 10y ago
        Well he answered me as if he understood me, so I am going to go ahead with that assumption. This thread is not at all difficult to follow. Anyone who uses rescue should be shot on sight--it takes a masochist to introduce panic as a stack unwind mechanism intended to be caught. The process should stop. I have never seen rescue used in the wild, so it seems as if the only thing this has in common with exceptions is stack unwinding. It is apples and oranges and the performance difference is meaningless unless you try to use them as the same. To be fair, pcwalton was not advocating this. He was pointing out that defer is already more costly runtime wise than exceptions, correcting another person.
        the_mitsuhiko 10y ago
        A big problem with both Rust and Go is that the marketing says there are no exceptions, and because we all know exceptions are bad/slow/hard to understand that the languages are superior. I strongly object to this idea because from an implementation POV both Go and Rust are 90% there for all the complexities that exceptions cause but now nobody is aware of it. (This is also why I'm a huge proponent of Results in Rust and disabling unwinding altogether)
        duaneb 10y ago
        Well, as I said earlier, stack unwinding does not imply that the stack unwinding is NORMAL; I'm fine with it in exceptional cases. Defer has its own quirks that irritate me but I wouldn't call them exceptional so much as dynamic RAII.... or something. Either way, if the languages allow me to avoid tracking down every possible http connection exception I need to trap to avoid bringing down my process I'd say it's a net win.
duaneb 10y ago
This was basically the point I was trying to make. :)
ktRolster 10y ago
I wouldn't mind seeing a powerful contracts implementation in C++. (Or any language, really).
coldtea 10y ago
>but having all those things go would become another C++ with a different syntax. Haskell and CL have "all those things" and they are not "C++ with a different syntax". I don't know why people repeat these cliches... It's not like a language can't have many features and be designed well at the same time. It just takes preparation and effort instead of ad-hoc additions (like with C++).
- duaneb 10y ago
  I'd argue either are just as bad as C++ if you actually use all those features, just like NOT using all those features turns your C++ readable. I'd also argue that Haskell does NOT support all the features directly but implements them through the language, which is a Good Thing. I consider CL a mess, so I probably shouldn't comment on it.
- geodel 10y ago
  But then there need not be raging debate about Go/Generics. As pragmatic developers can move to Haskell etc if Go has no value add to them.
  - coldtea 10y ago
    That reminds me of the "If those books say something worthwhile, it will be in the Kuran, too, so it's ok to burn them. If they don't, they it's ok to burn them anyway" argument -- something a sultan is alleged to have said as the justification for burning the library of Alexandria. The thing is, it's not just the feature set, different languages have lots of different things going (or not going) for them too. One might like Go's syntax over Haskell's. Another might not like Haskell's purity. A third might not like Haskell's heavyweight platform installation and tooling. Another might be forced to use Go because of his work but still hate the lack of Generics. Yet another might prefer Go over Haskell just for the fact that you can find Go jobs, where Haskell jobs are too few and far between.

pcwalton 10y ago

Exceptions don't have any runtime costs beyond those which Go is already paying by mandating unwinding. In fact, C++-style exceptions are strictly less expensive in the non-exceptional case than defer, because of defer's dynamic semantics. Go's semantics require a slower exceptional control flow scheme than almost any other language I'm aware of, including dynamic ones like JavaScript.

duaneb 10y ago
IIRC the idea is that the conceptual overhead of exceptions is much larger than the runtime cost, hence the minimal syntax/runtime support beyond defer (which is easy to follow, if hard to implement efficiently). I am not so sure I would agree with this, but I don't use go enough to have a firm opinion myself.
- pcwalton 10y ago
  Try/catch/finally is simpler than panic/recover/defer both conceptually and in implementation, due to the statically, lexically-scoped semantics.
  - enneff 10y ago
    As you probably already know, panic/recover/defer are not supposed to be used in the same way as try/catch/finally. They're different features for different purposes. If you want error handling in Go, use error values.
    - pcwalton 10y ago
      Sure. Panic, recover, and defer are in the language, though, and are more complex than exceptions regardless of how they're intended to be used.
  - duaneb 10y ago
    If recover is used in a file you never read, is its complexity relevant?
    - enneff 10y ago
      I think what's happening here is pcwalton is a language implementer, so when you talk about 'conceptual complexity' he thinks about how the feature is specified, whereas you or I think about how the users of the feature think about and use it. We're all talking past each other a bit, I think.
      - duaneb 10y ago
        Well he answered me as if he understood me, so I am going to go ahead with that assumption. This thread is not at all difficult to follow. Anyone who uses rescue should be shot on sight--it takes a masochist to introduce panic as a stack unwind mechanism intended to be caught. The process should stop. I have never seen rescue used in the wild, so it seems as if the only thing this has in common with exceptions is stack unwinding. It is apples and oranges and the performance difference is meaningless unless you try to use them as the same. To be fair, pcwalton was not advocating this. He was pointing out that defer is already more costly runtime wise than exceptions, correcting another person.
        the_mitsuhiko 10y ago
        A big problem with both Rust and Go is that the marketing says there are no exceptions, and because we all know exceptions are bad/slow/hard to understand that the languages are superior. I strongly object to this idea because from an implementation POV both Go and Rust are 90% there for all the complexities that exceptions cause but now nobody is aware of it. (This is also why I'm a huge proponent of Results in Rust and disabling unwinding altogether)
        duaneb 10y ago
        Well, as I said earlier, stack unwinding does not imply that the stack unwinding is NORMAL; I'm fine with it in exceptional cases. Defer has its own quirks that irritate me but I wouldn't call them exceptional so much as dynamic RAII.... or something. Either way, if the languages allow me to avoid tracking down every possible http connection exception I need to trap to avoid bringing down my process I'd say it's a net win.

duaneb 10y ago

This was basically the point I was trying to make. :)

ktRolster 10y ago

I wouldn't mind seeing a powerful contracts implementation in C++. (Or any language, really).

coldtea 10y ago

>but having all those things go would become another C++ with a different syntax. Haskell and CL have "all those things" and they are not "C++ with a different syntax". I don't know why people repeat these cliches... It's not like a language can't have many features and be designed well at the same time. It just takes preparation and effort instead of ad-hoc additions (like with C++).

duaneb 10y ago
I'd argue either are just as bad as C++ if you actually use all those features, just like NOT using all those features turns your C++ readable. I'd also argue that Haskell does NOT support all the features directly but implements them through the language, which is a Good Thing. I consider CL a mess, so I probably shouldn't comment on it.
geodel 10y ago
But then there need not be raging debate about Go/Generics. As pragmatic developers can move to Haskell etc if Go has no value add to them.
- coldtea 10y ago
  That reminds me of the "If those books say something worthwhile, it will be in the Kuran, too, so it's ok to burn them. If they don't, they it's ok to burn them anyway" argument -- something a sultan is alleged to have said as the justification for burning the library of Alexandria. The thing is, it's not just the feature set, different languages have lots of different things going (or not going) for them too. One might like Go's syntax over Haskell's. Another might not like Haskell's purity. A third might not like Haskell's heavyweight platform installation and tooling. Another might be forced to use Go because of his work but still hate the lack of Generics. Yet another might prefer Go over Haskell just for the fact that you can find Go jobs, where Haskell jobs are too few and far between.