STM und persistente Datenstrukturen

``The Clojure MVCC STM is designed to work with the persistent collections, and it is strongly recommended that you use the Clojure collections as the values of your Refs. Since all work done in an STM transaction is speculative, it is imperative that there be a low cost to making copies and modifications.''

``The values placed in Refs must be, or be considered, immutable!!''

Beispiel Suchbäume:

• destruktiv: Kind-Zeiger der Knoten verbiegen,
• persistent: neue Knoten anlegen.

Bsp: persistenter Suchbaum in Haskell