C++ pattern matching is coming (page 11)

10.1 Language Support for Variant
The design of this proposal also accounts for a potential language support for variant. It achieves this by keeping
the alternative pattern flexible for new extensions via < new_entity > pattern.
Consider an extension to union that allows it to be tagged by an integral, and has proper lifetime management
such that the active alternative need not be destroyed manually.

On Friday, 28 October 2022 at 15:29:15 UTC, ryuukk_ wrote:

On Friday, 28 October 2022 at 14:49:28 UTC, Nick Treleaven wrote:

On Friday, 28 October 2022 at 14:47:27 UTC, ryuukk_ wrote:

On Friday, 28 October 2022 at 14:43:54 UTC, Nick Treleaven wrote:

Has C or C++ actually added sum types to their standards?

It was proposed and feedback was favorable, it's only just a matter of when now

Do you have a link? I saw the circle compiler extension and feedback wasn't all favourable. Standardising something is long and arduous.

Here is the latest revision i could find

https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p1371r3.pdf

And Bjarne Stroustrup thoughts

https://www.open-std.org/JTC1/SC22/WG21/docs/papers/2021/p2411r0.pdf

Final words

I am still of the opinion that after a general model of concurrency, a module version of the standard
library, and library support for coroutines, pattern matching is the most promising addition to the
language for the (relatively) near future [P2000].

This is just the pattern matching part I am guessing. I do not see any built-in sum type there such as Rust's enum or Haskell/Ocalm style stuff for sum types. There is the std::variant library type so far.

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