persistent/functional/immutable data structures
Pyrsistent is a number of persistent collections (by some referred to as
functional data structures). Persistent in the sense that they are
immutable.

All methods on a data structure that would normally mutate it instead
return a new copy of the structure containing the requested updates. The
original structure is left untouched.

Maintainer: The OpenBSD ports mailing-list <ports@openbsd.org>

WWW: http://github.com/tobgu/pyrsistent/
