[rybosome]

Fun! From the repo[0]:

> Your function must be self-contained, such that someone could copy-paste it into their code and not get an error. It also must not effect the environment outside it if at all possible (no #define or mutating globals). It must be as "pure" and self-contained as the language will allow.

This is an interesting restriction, actually, with respect to style. The “natural” way I would program such an algorithm certainly doesn’t adhere to this requirement.

Producing functions that are still correct, idiomatic and legible while producing minimal changes to environment or state requires a non-beginners understanding of the runtime nature of the language.

[0]: https://github.com/oliverkwebb/moonphase?tab=readme-ov-file#...

[oliverkwebb]

This is also interesting for speed, The algorithms ran by all the impls are identical, but sacrificing speed for cleanliness and adherence to spirit is done regularly.

Without having actually measured, the rust impl probably runs faster than the C impl, but that's not because rust is "faster" than C. That's because I used a closure with one call to floor() for modulus in rust, whilst in C I did 2 fmod()'s to get it because the alternative would've been to make the code unreadable or add a second function/macro (although thinking about it now, undef does exist...)

[danparsonson]

Could you elaborate on this? Maybe an example of what you mean?