STM is implemented using immutable data structures and using atomics you can do a compare and swap to update the value. If the swap fails you try your transact

STM is implemented using immutable data structures and using atomics you can do a compare and swap to update the value. If the swap fails you try your transaction again. I’m not sure how you would implement this in a language with mutable data structures easily. I know Azul had hardware transactional memory that supported its.