Purely Functional Data Structures

Purely functional data structures are ways of organizing and managing data that avoid changing existing data directly. Instead, any modifications create new versions, leaving earlier ones unchanged. This approach ensures safe, predictable behavior, simplifies debugging, and enables easy undo operations. They rely on immutability—once data is created, it cannot be altered—making systems more reliable, especially in concurrent or multi-threaded environments. This design emphasizes pure functions that produce new data without side effects, leading to more maintainable code with clear data flow.