I get where you are coming from. Just propose a runtime dynamic index for the existing std::tuple. The implementors will take care of it and it will be fast.   Also creating a std::variant to a pointer or (extended to a reference) on the fly will be fast. No need to put a pre-created std::variant copy into the tuple or array.   The recursive definition will not matter for the runtime-speed or optimization potential. That is the implementors' job.     It could (!) be that some implementations are slow *at compile-time* for very long heterogeneous lists implemented with std::tuple. In this case that is not a topic for the standard (nothing it could do to help), but for the implementations to optimize their compilation.   -----Ursprüngliche Nachricht----- Von:Muneem via Std-Proposals <std-proposals_at_[hidden]> Gesendet:Mo 20.04.2026 11:01 Betreff:Re: [std-proposals] Extension to std::tuples to allow runtime indexing. An:std-proposals_at_[hidden]; CC:Muneem <itfllow123_at_[hidden]>; It is not relevant, but mentioned it to just say that their existing structure is normally just a dumb recursion which is perfect for compile indexing, but not for complex optimizations that are to reduce a runtime indexing operator to 0(1) complexity.  I am sorry that I didn't reply to all the previous responses, I was a little tired from writing the code. On Mon, 20 Apr 2026, 1:41 pm Sebastian Wittmeier via Std-Proposals, <std-proposals_at_[hidden] <mailto:std-proposals_at_[hidden]> > wrote: Is it relevant, whether tuples are recursively defined, or not? It is the programming style for functional programming. Doesn't mean that indexes are resolved recursively at runtime.   -----Ursprüngliche Nachricht----- Von:Muneem via Std-Proposals <std-proposals_at_[hidden] <mailto:std-proposals_at_[hidden]> > Gesendet:Mo 20.04.2026 10:03 Betreff:Re: [std-proposals] Extension to std::tuples to allow runtime indexing. An:std-proposals_at_[hidden] <mailto:std-proposals_at_[hidden]> ; CC:Muneem <itfllow123_at_[hidden] <mailto:itfllow123_at_[hidden]> >; Sorry for sending too many emails at one( I really am ): https://github.com/HjaldrKhilji/Future-potential-ISO-porposals/blob/main/Runtime_Indexed_Tuples_Proposal_Official%20(1).pdf  (in case you couldnt see my proposal as attached then this is the link)  On Mon, Apr 20, 2026 at 1:00 PM Muneem <itfllow123_at_[hidden] <mailto:itfllow123_at_[hidden]> > wrote: My proposal with conceptual implementation that you can run but the implementation does not have the exact implementation as one with std::variant<T&...> would have, like I could modify it but it would never be one to one, so see my implementation as a conceptual implementation roadmap meant to show how bookkeeping helps rather than showing the exact semantics of my implementation.  I also fixed some Typos and grammar mistakes (in the code example section) that were in my updated docx file. On Mon, Apr 20, 2026 at 12:47 PM Muneem <itfllow123_at_[hidden] <mailto:itfllow123_at_[hidden]> > wrote: Credits to this video: https://www.youtube.com/watch?v=LDPMpc-ENqY like in this video, at the end, he describes std::apply that was useful for folding tuples for me. I was lucky to see this a month ago while learning random number generators and reading Bjarne's great book. Without this video, My code couldn't be completed, like most of it is basic, except the part where I used std::apply because that was what took 3 hours to get a hint of, which is when this video came into mind somehow. Funny how the world is, like I programmed in my dream, literally solving this puzzle. This puzzle may look basic to the old timers but for me, this basic puzzle took like an honest 4 hours to prototype and 6 hours to fix completely(about 10 if you count the 2-4 hours in my dream). On Mon, Apr 20, 2026 at 12:25 PM Muneem <itfllow123_at_[hidden] <mailto:itfllow123_at_[hidden]> > wrote: My code is complete: https://github.com/HjaldrKhilji/Future-potential-ISO-porposals/blob/main/Code_example.cpp https://godbolt.org/z/WWoWrd3q1 My updated proposal is also attached and is also on the github link: https://github.com/HjaldrKhilji/Future-potential-ISO-porposals/blob/main/Runtime_Indexed_Tuples_Proposal_Official%20(1).docx Again, I am sorry for taking so much time on such trivial code. I know I should be faster, so hope it dosent reflect badly on the technical merit of my proposal On Sun, Apr 19, 2026 at 11:22 PM Muneem <itfllow123_at_[hidden] <mailto:itfllow123_at_[hidden]> > wrote: https://godbolt.org/z/rs34q1Wj9 This is what I got till today,  I will debug this tomorrow, but yeah, I just wanted to show what's done till now before going to sleep. On Sun, Apr 19, 2026 at 8:54 PM Muneem <itfllow123_at_[hidden] <mailto:itfllow123_at_[hidden]> > wrote: I am really really sorry that previously my code was not only using enable if but also the pattern of making types unique was wrong. I promise that I will fix it tomorrow and will test every possible specialization to make sure such mistakes don't occur again. Again, really really sorry. I am almost done with the proper code but it's just a little bit left that I left for tomorrow. I know it's nothing special and that I should be better at wiring such basic code but things happen and in my case, it would to not think properly so as to use recursion with conditinal_t.   Regards, Muneem On Sun, 19 Apr 2026, 8:28 pm Thiago Macieira via Std-Proposals, <std-proposals_at_[hidden] <mailto:std-proposals_at_[hidden]> > wrote: On Sunday, 19 April 2026 01:01:13 Pacific Daylight Time Muneem via Std- Proposals wrote: > This is the example implementation code: Send the link to the working implementation in godbolt or your repository on GitHub/GitLab/equivalent. -- Thiago Macieira - thiago (AT) macieira.info <http://macieira.info> - thiago (AT) kde.org <http://kde.org>   Principal Engineer - Intel Data Center - Platform & Sys. 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