A collection of functions to generate combinatorial objects like partitions, combinations, permutations, Young tableaux, various trees, etc.

The long-term goals are

1. to be efficient;
2. to be able to enumerate the structures with constant memory usage.

The short-term goal is to generate many interesting structures.

Naming conventions (subject to change):

• prime suffix: additional constrains, typically more general;
• underscore prefix: use plain lists instead of other types with enforced invariants;
• "random" prefix: generates random objects (typically with uniform distribution);
• "count" prefix: counting functions.