Persistent/Functional/Immutable Data Structures

Pyrsistent is a Python library providing persistent and immutable data structures, such as lists, dictionaries, and sets, that facilitate functional programming paradigms. Unlike mutable data structures, all operations that would typically modify a `pyrsistent` object instead return a new, updated copy, leaving the original untouched. This simplifies reasoning about program state by eliminating hidden side effects. The library is currently at version 0.20.0, released in October 2023, and is actively maintained.