A new way to manage memory: no garbage collection, extremely fast & safe access

U is a programming language with a novel memory management system that eliminates garbage collection by using directed acyclic graph (DAG) ownership where owners and their entire subtrees are deallocated when the owner's reference count reaches zero. The system combines several techniques including power-of-two slab chains for efficient allocation, NaN-boxed 8-byte tagged values, and stable indices that prevent data relocation, achieving both safety and performance without tracing garbage collection overhead.