Permutation Memory Issues

[Chadtech]

In the slack channel, Numiastowski discovered that permutations causes a memory problem. A list of 9 elements might have as many as 9! permutations, and therefore, 9! stack calls.

I believe this can be solved by implementing something like this: https://www.nayuki.io/page/next-lexicographical-permutation-algorithm, or ~~any non-recursive permutation function~~.

But before settling on that, we should consider use cases of the permutation function. Has anyone used it? How did you use it? What problem did it solve for you?

[pzp1997]

Maybe it should be lazy?

[Chadtech]

@zwilias made this cool Ellie app demonstrating an implementation of the next permutation algorithm. Could be useful to this project : https://ellie-app.com/3vnrtbJffbYa1/0

[pzp1997]

We might want to consider the implementation of subsequences as well, which outputs a list of 2ⁿ lists for an input list of length n.