Clojure's ML/stats ecosystem is moving fast. Several important libraries are under construction and will mature in few months. Imho, it is worth following this year, for anyone interested in languages for ML/stats.
In addition to probabilistic programming libraries such as Metaprob and Anglican mentioned above, here are some libraries worth mentioning: https://github.com/MastodonC/kixi.stats https://github.com/generateme/fastmath https://github.com/techascent/tech.ml