Thanks, skimming through clojure's website it mentions that Clojure simplifies multi-threaded programming in several ways. Because the core data structures are immutable, they can be shared readily between threads. which is exactly what you said, I though its concurrency features where emphasized more on its refs stuff(refs, agents) or futures, delays, promises. Also reading that clojure being hosted is a feature then I guess leveraging the host is idiomatic, (using Thread or other concurrency APIs).

Can you elaborate on why using Thread was the intended way to use Clojure for concurrency?