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Carbon Language: An experimental successor to C++

docs.carbon-lang.dev

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Re: Carbon Language: An experimental successor to C++

#161

Post by throwaway293873 »

kjksf wrote: post #50

I think this page describes "what" but not "why" of Carbon. Carbon exists so that it's possible to migrate a large C++ code base, like Chrome, from C++ to something saner, incrementally. The most important attribute of Carbon is not the specifics of the syntax but the fact that it's designed to be used in a mixed C++ / Carbon code base and comes with tooling to convert as much of C++ as possible to Carbon. That's wha…

The real "why" is because, unlike other languages, Google can't strong-arm or bribe C++'s ISO committee into doing its bidding, and that has caused problems for Google in the past. Carbon is a language born out of a corporate hissy fit.

Re: Carbon Language: An experimental successor to C++

#162

Post by aw1621107 »

justcuriousab wrote: post #154
aw1621107 wrote: post #149

Earlier quoted context omitted.

> Rust is often somewhat stable, but not always. > https://internals.rust-lang.org/t/type-inference-breakage-in ... > https://github.com/rust-lang/rust/issues/127343 > 300 comments on Github. > https://github.com/NixOS/nixpkgs/pull/332176 Might worth noting that this change technically doesn't violate Rust's stability guarantees since type inference changes and/or adding new impls are exempt. Of course, that doesn't…

I wonder if the guarantees could be amended, considering the reactions from the Rust community.

They could be amended, but I suspect they will not be. There's a reason those exemptions were added in the first place, and the impression I get is that the 1.80 issues were more of a social problem that doesn't significantly change the reasons the exemptions were added in the first place.

In addition, as I mentioned I don't think this is the first time Rust has had to navigate this kind of wide-ranging technically-allowed-but-still-breaking change. The Rust devs first created a PR to change its internal representation for IP addresses in November 2020 [0], but multiple major libraries (including mio, which tokio depends on) incorrectly assumed that the representation for Rust's IP address type was the same as libc's representation and basically type punned between the two, so the change would result in UB. The Rust devs could have pushed out the change anyways, as the change didn't violate the backwards compatibility guarantee due to just being an internal implementation detail change, but the PR didn't actually land until July 2022 [1] because the Rust devs wanted to give the ecosystem time to migrate.

More discussion at [2].

[0]: https://github.com/rust-lang/rust/pull/78802

[1]: https://github.com/rust-lang/rust/pull/78802#event-709670882...

[2]: https://old.reddit.com/r/rust/comments/wcw93o/a_major_refact...

Re: Carbon Language: An experimental successor to C++

#163

Post by pjmlp »

throwaway293873 wrote: post #161
kjksf wrote: post #50

I think this page describes "what" but not "why" of Carbon. Carbon exists so that it's possible to migrate a large C++ code base, like Chrome, from C++ to something saner, incrementally. The most important attribute of Carbon is not the specifics of the syntax but the fact that it's designed to be used in a mixed C++ / Carbon code base and comes with tooling to convert as much of C++ as possible to Carbon. That's wha…

The real "why" is because, unlike other languages, Google can't strong-arm or bribe C++'s ISO committee into doing its bidding, and that has caused problems for Google in the past. Carbon is a language born out of a corporate hissy fit.

Depends on how much people one sends to WG21 voting sessions, some folks at Reddit would assert contracts only got into C++26, thanks to Bloomberg votes.

Re: Carbon Language: An experimental successor to C++

#164

Post by germandiago »

kjksf wrote: post #50

I think this page describes "what" but not "why" of Carbon. Carbon exists so that it's possible to migrate a large C++ code base, like Chrome, from C++ to something saner, incrementally. The most important attribute of Carbon is not the specifics of the syntax but the fact that it's designed to be used in a mixed C++ / Carbon code base and comes with tooling to convert as much of C++ as possible to Carbon. That's wha…

In which way is C++ an "objectively pretty bad language"?

I have done C++ for a living and it is not the easiest but there is tooling and warnings as errors that catch a lot of the errors before even you make a mistake.

It is true that packaging is more challenging but it is also true that it is very configurable ro squeeze performance as much as possible (which is on of C++'s niches). And by squeezing I mean beyond setting a release build. You could for example decide to go with LTO + PGO + remove position independent code and do static linking for all dependencies, for example.

You can do virtually anything that no other language can do and whwn you need it, believe me it is useful.

But you can still code every day code wirh your lambdas, ranges, smart pointers and virtual interfaces.

I understand C++ has some baggage but is is very far from being an "objectively bad language" in ly opinion. More so if you take into account its performance and library availability, which is second to none for almost any task, except maybe for the typical enterprise-like Java app or web stuff, byt niw C++26 will include reflection and annotations, so this could be a game changer.

Re: Carbon Language: An experimental successor to C++

#165

Post by steveklabnik »

aw1621107 wrote: post #162
justcuriousab wrote: post #154

Earlier quoted context omitted.

I wonder if the guarantees could be amended, considering the reactions from the Rust community.

They could be amended, but I suspect they will not be. There's a reason those exemptions were added in the first place, and the impression I get is that the 1.80 issues were more of a social problem that doesn't significantly change the reasons the exemptions were added in the first place. In addition, as I mentioned I don't think this is the first time Rust has had to navigate this kind of wide-ranging technically-a…

Yes, this was a social issue more than a technical one.

At the same time, I was affected by this breakage, and it took me all of ten minutes to fix. So I both understand the outrage, and agree with it in general, but also, it was a tad overblown, I think.

Should they have done a slower rollout, like the IpAddr change? Probably. Is it the end of the world that they made a mistake? Nah. But if it happens more often, that's cause for concern.

Re: Carbon Language: An experimental successor to C++

#166

Post by pjmlp »

yegle wrote: post #58
kjksf wrote: post #50

I think this page describes "what" but not "why" of Carbon. Carbon exists so that it's possible to migrate a large C++ code base, like Chrome, from C++ to something saner, incrementally. The most important attribute of Carbon is not the specifics of the syntax but the fact that it's designed to be used in a mixed C++ / Carbon code base and comes with tooling to convert as much of C++ as possible to Carbon. That's wha…

A similar example is Facebook/Meta inventing Hack to progressively replacing the old PHP code.

Although it was a journey, starting with HipHop and other tools before arriving there.

Re: Carbon Language: An experimental successor to C++

#167

Post by pjmlp »

troad wrote: post #104
kjksf wrote: post #50

I think this page describes "what" but not "why" of Carbon. Carbon exists so that it's possible to migrate a large C++ code base, like Chrome, from C++ to something saner, incrementally. The most important attribute of Carbon is not the specifics of the syntax but the fact that it's designed to be used in a mixed C++ / Carbon code base and comes with tooling to convert as much of C++ as possible to Carbon. That's wha…

That seems like a really neat idea. One other use case I could think of is gaming, where there is an incredible amount of load-bearing C++ code that's never realistically going to be rewritten, and strict memory safety is not necessarily a sine qua non in the way it is in other fields.

Depends on the kind of game, and lack of security is how piracy thrives.

Re: Carbon Language: An experimental successor to C++

#168

Post by pjmlp »

owl_vision wrote: post #79
kjksf wrote: post #50

I think this page describes "what" but not "why" of Carbon. Carbon exists so that it's possible to migrate a large C++ code base, like Chrome, from C++ to something saner, incrementally. The most important attribute of Carbon is not the specifics of the syntax but the fact that it's designed to be used in a mixed C++ / Carbon code base and comes with tooling to convert as much of C++ as possible to Carbon. That's wha…

> Carbon exists so that it's possible to migrate a large C++ code base, like Chrome, from C++ to something saner, incrementally. _Incrementally_: a C++ project can be incrementally made more sane also using constructs to avoid and constructs to use once the problem domain is confined. In my past, I had successfully implemented this quest for 3 different fairly large C++ projects. This is not a strong selling point fo…

Assuming the right culture, which unfortunately many C++ shops lack, that is why we have things like Orthodox C++ and similar movements.

Re: Carbon Language: An experimental successor to C++

#169

Post by twoodfin »

germandiago wrote: post #164
kjksf wrote: post #50

I think this page describes "what" but not "why" of Carbon. Carbon exists so that it's possible to migrate a large C++ code base, like Chrome, from C++ to something saner, incrementally. The most important attribute of Carbon is not the specifics of the syntax but the fact that it's designed to be used in a mixed C++ / Carbon code base and comes with tooling to convert as much of C++ as possible to Carbon. That's wha…

In which way is C++ an "objectively pretty bad language"? I have done C++ for a living and it is not the easiest but there is tooling and warnings as errors that catch a lot of the errors before even you make a mistake. It is true that packaging is more challenging but it is also true that it is very configurable ro squeeze performance as much as possible (which is on of C++'s niches). And by squeezing I mean beyond…

Explicitly and between the lines, Carruth and Google have made it clear that the “bad” part of C++ from their perspective is the standards committee.

In particular, the committee’s unwillingness to make ABI-breaking changes to the language, or more abstractly, to consider the needs of organizations with huge active code bases at least as seriously as those with huge legacy code bases.

Re: Carbon Language: An experimental successor to C++

#170

Post by tialaramex »

cb321 wrote: post #150
tialaramex wrote: post #137

Earlier quoted context omitted.

The open addressed hash tables basically don't exist for a long time. The various strategies for collision handling in these tables are from the 1980s or later and if you don't have a collision strategy you can't use this as a general purpose container. I'm pretty sure I never used a hash table which didn't use separate chaining until at least the 1990s and perhaps later. So that's maybe a bad example. In the same wa…

I can't speak to what libraries you used, but both techniques have been broadly used in common practice since the 1950s. According to the "History" subsection in Knuth TAOCP v3 at the very end of 6.4 (whose very first edition written in 1972 covered OA with various probe/collision strategy ideas), both open addressing & separate chaining were co-invented at IBM in 1953/54 by Luhn & Amdahl. You may be confusing the Ce…

None of the schemes I was aware of pre-date Celis in 1985 but it's apparent upon actually reading Celis [which I hadn't done previously] that he's only improving on an existing state of the art, so I was entirely wrong about that. That state of the art was pretty dire by my reckoning, but it's clear that it would have worked so I was entirely wrong and I apologise for being so assertive when in fact I clearly didn't know what I was talking about.
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