Custom error types and error factory functions

Collection of ~170 lightweight, composable transducers, reducers, generators, iterators for functional data transformations

Collection of 70+ type, feature & value checks

Mutable wrappers for nested immutable values with optional undo/redo history and transaction support

Extensible deep value equivalence checking for any data types

Immutable, optimized and optionally typed path-based object property / array accessors with structural sharing