Carbon (programming language): Difference between revisions

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| designer = [[Google]]

| typing = [[Static type|Static]], [[Nominal type system|nominative]], [[Type inference|partly inferred]]

| influenced by = [[C++]], [[Rust (programming language)|Rust]], [[SwiftZig (programming language)|SwiftZig]], [[Haskell {{cn(programming language)|dateHaskell]], [[Kotlin (programming language)|Kotlin]], [[Swift (programming language)|Swift]]<ref name=August"cppnorthkeynote-video" 2023}}/>

| programming language = [[C++]]

| license = [[Apache-2.0-with-LLVM-Exception]]

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}}

'''Carbon''' is an experimental [[programming language]] designed for interoperability with [[C++]].<ref name="readme">{{cite web|title=README|url=https://github.com/carbon-language/carbon-lang/blob/trunk/README.md|quote="It is designed around interoperability with C++ as well as large-scale adoption and migration for existing C++ codebases and developers."|accessdate=2023-09-06}}</ref> The project is [[Open-source software|open-source]] and was started at [[Google]]. Google engineer Chandler Carruth first introduced Carbon at the CppNorth conference in [[Toronto]] in July 2022. He stated that Carbon was created to be a C++ successor.<ref name="cppnorthkeynote-sched" /><ref name="cppnorthkeynote-video" /><ref name="cppnorthkeynote-9to5google" /> The language is expected to have aan 1.0experimental release[[Minimum viable product|MVP]] version 0.1 in 2024late 2026 at the earliest and a production-ready version 1.0 orafter 20252028.<ref>{{Citation |title=Carbon Language: An experimental successor to C++Roadmap |date=20222024-1001-1211 |url=https://github.com/carbon-language/carbon-lang/blob/9feff92f223e1a855abf2b343387d8460f63317btrunk/docs/project/roadmap.md |publisher=carbon-language |access-date=20222024-1001-1218}}</ref>

The language intends to fix several perceived shortcomings of C++<ref name="difficulties improving cpp" /> but otherwise provides a similar feature set.

The main goals of the language are readability and "bi-directional interoperability" (which allows the user to include C++ code in the Carbon file), as opposed to using a new language like [[Rust (programming language)|Rust]], that, whilewhilst being influenced by C++, is not two-way compatible with C++ programs. Changes to the language will be decided by the Carbon leads.<ref name="c1" /><ref name="c2" /><ref name="c3" /><ref name="c4" />

Carbon's documents, design, implementation, and related tools are hosted on [[GitHub]] under the [[Apache License|Apache-2.0]] license with [[LLVM]] Exceptions.<ref>{{Cite web |url=https://github.com/carbon-language/carbon-lang/blob/31df852738aea520a1a1800259120bc10ce7a005/LICENSE |title=carbon-lang/LICENSE |date=2020-06-16 |access-date=2022-07-24 |website=GitHub}}</ref>

==Example==

The following shows how a program might be written in Carbon and C++:<ref>{{cite web |title=carbon-lang/docs/images/snippets.md at trunk · carbon-language/carbon-lang |url=https://github.com/carbon-language/carbon-lang/blob/trunk/docs/images/snippets.md |website=GitHub |access-date=16 December 2023 |language=en}}</ref>

The following shows how a [["Hello, World!" program]] is written in Carbon:

{{clear}}

<!--

Part of the Carbon Language project, under the Apache License v2.0 with LLVM

Exceptions. See https://github.com/carbon-language/carbon-lang/blob/9a7b7c2b8be3bcf288d29eb9b7afbf37fb471c1b/LICENSE for license information.

SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

Source: https://github.com/carbon-language/carbon-lang/blob/9a7b7c2b8be3bcf288d29eb9b7afbf37fb471c1b/docs/images/snippets.md

-->

{| class="wikitable"

|-

! Carbon !! C++

|- style=vertical-align:top

| <syntaxhighlight lang="carbon" line="1">

package Sample apiGeometry;

import Math;

class Circle {

<syntaxhighlight lang="carbon" line="1">

var r: f32;

package Sample api;

}

fn PrintTotalArea(circles: Slice(Circle)) {

var area: f32 = 0;

for (c: Circle in circles) {

area += Math.Pi * c.r * c.r;

}

Print("Total area: {0}", area);

}

fn Main() -> i32 {

// A dynamically sized array, like `std::vector`.

var s: auto = "Hello, World!";

var circles: Array(Circle) = ({.r = 1.0}, {.r = 2.0});

Print(s);

// Implicitly converts `Array` to `Slice`.

return 0;

PrintTotalArea(circles);

return 0;

}

</syntaxhighlight>

| <syntaxhighlight lang="c++" line="1">

The following is the equivalent "Hello, World!" program written in C++:

#include <iostreamvector>

<syntaxhighlight lang="c++" line="1">

using namespace std;

#include <iostream>

struct Circle {

float32_t r;

};

void PrintTotalArea(span<Circle> circles)

{

float32_t area = 0;

for (const Circle& c : circles) {

area += numbers::pi * c.r * c.r;

}

print("Total area: {}\n", area);

}

int main() {

vector<Circle> circles{{.r = 1.0}, {.r = 2.0}};

auto s = "Hello, World!";

// Implicitly converts `vector` to `span`.

std::cout << s;

return 0;

PrintTotalArea(circles);

return 0;

}

</syntaxhighlight>

|}

==See also==

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* [[C++]]

* [[D (programming language)|D]]

* [[Go (programming language)|Go]]

* [[Rust (programming language)|Rust]]

* [[Mojo (programming language)|Mojo]]

== References ==

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|url=https://cppnorth2022.sched.com/event/140f8/keynote-chandler-carruth-nulbscience-experiment-timenulb?linkback=grid

|title=Scheduled events for Tuesday, July 19, 09:00 - 10:30

|work=CppNorth, The Canadian C++ Conference, July 17-2017–20, 2022

|publisher=CppNorth

|via=Sched.com

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== External links ==

* {{GitHub|carbon-language}}

* [https://docs.carbon-lang.dev/ Carbon language documentation]

* [https://carbon.godbolt.org/ Carbon at the Compiler Explorer (godbolt)]

{{Google FOSS}}

{{Google LLC}}

[[Category:Google]]

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[[Category:Object-oriented programming languages]]

[[Category:Programming languages created in 2022]]

[[Category:Google software]]

{{Google FOSS}}

{{Google LLC}}

{{Google-stub}}