Lifetimes and ownership are about finding use-after-free and double-free bugs. The fact that they enable automatic memory management without a tracing GC overhe

Lifetimes and ownership are about finding use-after-free and double-free bugs. The fact that they enable automatic memory management without a tracing GC overhead is just a cherry on top. For a long time languages were stuck with the false dichotomy of either trying to be 100% safe (and pay the cost of a VM/sandbox/GC) or said "halting problem" and gave up. Rust solved this dilemma by allowing safe abstractions around unsafe blocks. It works like a charm — I get speed I got from C, but don't have to use gdb. There's option 3) use program architecture that has clearer ownership and less shared mutable state. Borrow checker doesn't like doubly linked lists or mutual parent-child relationships. Instead you use different containers and DAG structures. And when you still have to have shared ownership without a clear scope, then you use refcounting. The nice thing in Rust is that (unlike C++/ObjC/Swift) it doesn't always have to be atomic in multi-threaded programs, and objects can be borrowed and used without touching the refcount.