This is a package for working with symmetric functions. It has the core bases, as well as Jack and Macdonald polynomials, LLT polynomials, SchurP and SchurQ functions, the Hall inner product, plethysm and the Delta operator.
This also has support for working multiple alphabets, which is useful when dealing with plethysm calculus.
Compare with Stembridge's sf package for Maple, or Curtis Greene's symfun13 package.