AbstractAlgebra defines a series of interfaces that can be extended with new types that implement those interfaces. For example, if one were implementing a new polynomial ring type, one would implement all of the required functionality described in this chapter for the relevant AbstractAlgebra interfaces. This would include the Ring Interface and the Univariate Polynomial Ring Interface.
Once a new type implements all the required functionality, all the corresponding generic functionality would then function automatically for the new type.
One may then go on to implement some of the optional functionality for performance if the provided generic functionality is insufficient.
AbstractAlgebra tries to provide all generic constructions recursively so that one can have towers of generic constructions. This means that new interfaces should generally only be added if they cooperate with all the existing interfaces, at least so far as the theory exists to do so.