What does HackerNews think of tesser?
Clojure reducers, but for parallel execution: locally and on distributed systems.
All of these options are, IME, relatively easy to drop in to some extant data processing pipeline to parallelize it, and probably require a similar level of finagling to what you're used to in Haskell.
[0] (->> some-lazy-seq (pmap ...) (reduce ...)) goes pretty far, but nesting/composing pmaps or doing i/o doesn't always work particularly well since the JVM [currently] uses OS threads rather than something like the lightweight threads GHC provides.
[1] https://clojure.org/reference/reducers
From a brief examination tesser looks a lot simpler (probably because of encoding most of the folding using various monoids). Does onyx have a similar abstraction model that I missed?
On first look: "No loops?" "This reduce functions everyhere look ugly."
On second look: "Oh, I can import paralel reduce instead of the single-threaded one?" [1] "Somebody created a library to transparently switch between local reduce and one using hadoop?" [2]
[1] http://clojure.org/reducers [2] https://github.com/aphyr/tesser