I haven't tried it and am afk rn but I'd imagine you just define a constexpr function that implements collatz and use that in your contract.

(Edit: if the input is constexpr itself) Its also quire easy to think about specializing a few templates and doing it that way. If you look up an example of the fib sequence in c++ templates you'll get the general idea.

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kelseyfrog 3 hours ago | parent [-]

I feel like I'd have something to learn from seeing the code.

Won't you just run into a constexpr evaluation depth error with a suggestion to set -fconstexpr-depth? I don't see how this is the gotcha it's made out to be.

	▲	tyromaniac 3 hours ago \| parent [-]
		I'd exepct something like that to happen. Worth reiterating that the whole scenario is for a hypothetical different implementation of contract that would execute comptime, as noted in the parent thread. If you wanted a c++26 preconditon for collatz tho, here it is. ```cpp bool collatz(unsigned long long n) { while (n != 1) n = n % 2 ? 3 * n + 1 : n / 2; return true; } void f(unsigned long long n) pre(collatz(n)); ``` That's basically what you'd write if you were doing it with asserts, as the linked article states, just now you add it to the declaration.