Over the last few days, when I should have been doing other things, I've been programming up a few combinatorial algorithms, to supplement those already in the system. I've programmed as a sort of proof-of-concept in the interactive language.
The functions include generators for powersets, subsets, set partitions, permutations and derangements (of sets and multisets), and the numbers involved.
So attached are two files: combinatorics.input, which contains the programs, and combinatorics.pdf, which describes the functions.