On 4/5/26 16:54, Emanuel Spiridon wrote:
> Yes, the proposal from 2018 is quite similar to mine, however that
> proposal is trying to standardize Boost.Mp11 as a general purpose meta
> programming toolkit.
> P0949 was proposed in 2018 but was not adopted, and predates C++20
> concepts entirely.
My point was that having a type algorithm (contains) that only works
with a dedicated type-list type rather than arbitrary templates means
that the type algorithm has limited utility.
> I am proposing the minimal building blocks needed for named, composable
> type sets for concept constraints, without requiring users to learn a
> full meta programming library.
Another proposal that looks a lot like yours is
https://wg21.link/N4115
It may be worth investigating why this was not adopted.
About your proposal, the subsumption example using numbers is not great,
because we already have std::is_arithmetic for that.
I am sorry for having to reply twice, but I forgot to reply to this part.
A reason N4115 didn't pass could be that concept constraints weren't standardized in 2014, my proposal is very similar by the looks of it, but it targets a feature that exists and could be developed further.
I used the types we are familiar with to demonstrate subsumption, I didn't believe it was necessary to use additional user defined classes for this example
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