Three different algorithms for generating permutations, Lexicographic, Steinhaus-Johnson-Trotter-Even, and a recursive algorithm.
All three are reasonably efficient and might be useful as they are but really the package is a bit a dabbling at this point.
It started with a desire to generate permutations in SJT order. I found the Wikipedia explanation of the SJTE algorithim unclear and found a lot of craziness when I looked for existing implementations on the internet. Coding just to Wikipedia’s description of the "recursive structure," I came up with the recursive algorithm in this package. But then wanting to benchmark my algorithm against others, I puzzled out the iterative SJTE and also the lexicographic algorithms. All three turn out to be very fast.
If you are interested in using them, note that their APIs are a little different. Read the doc and look at the examples.