Add recursive fibonacci benchmark

[devyn]

This is pretty much the least efficient reasonably simple way to implement fibonacci in Nushell, and it's a good benchmark to profile our custom command call performance, as this is the majority of the work being done.

I think it may actually be good to add this and the other one to cargo bench so we can track it over time, but it's also useful as a script so it can easily be profiled.

[fdncred]

Thanks. There's also a --pretty on bench that summarizes the output.

[amtoine]

is my implementation faster? 😊

let PHI = (1 + (5 | math sqrt)) / 2  # cannot make that a true constant unfortunately

export def fibo [n: int]: [ nothing -> int ] {
    ($PHI ** $n - (1 - $PHI) ** $n) / (5 | math sqrt) | math round --precision 0
}

[fdncred]

We could make the math commands const if that's something people are interested in. I just did math sqrt for funsies.

❯ const PHI = (1 + (5 | math sqrt)) / 2
❯ $PHI
1.618033988749895

There's also PHI defined in the std lib although I always forget how to use it.

❯ use std math PHI
❯ $PHI
1.618033988749895

[devyn]

I'm sure it is, though finding the fastest way to do fib isn't really the goal here 😉

[amtoine]

@fdncred honestly, i think this is a good idea, solely to be able to define mathematical constants as you did 👍

[devyn]

Yeah Rust doesn't allow floating point math in constants for various reasons (external floating point state I think being a major one), but we don't really have that problem, it should be fine for us