FRP-inspired state propagation library for ClojureScript.



Montoux Follow

A Functional Reactive Programming (FRP) inspired library for managing state in ClojureScript.

Followers bring FRP ideas to a ClojureScript stack, e.g. for use with React. A follower is a data transformation function raised to operate over state, where state can be encapsulated by Atoms, or other followers. When state changes, the follower will recompute its internal value and notify listeners so they can respond to the change, as long as the internal value is has changed.

When a state update occurs, the API performs a topological sort then updates followers in order to ensure that each follower will only recompute once per state change (each listener will only be called once).

Followers are stateful objects with references to their state sources, so they need to be cleaned up manually when they are no longer required.


(let [a (atom 1)
      b (f/follow (partial * 2) a)
      c (f/follow (partial * 2) b)
      d (f/follow + a b c)]
  (add-watch d :print (fn [k r o n] (println n)))

  (reset! a 2)          ;; prints 14
  (reset! a 1)          ;; prints 7

  (run! f/dispose [b c d]))

(let [f  (f/lift repeat)
      n! (f/latch identity 1)]
  (add-watch f :print (fn [k r o n] (println n)))
  (f/partial f n)
  (f/bind f (atom "x")) ;; prints [x]
  (n! 5)                ;; prints [x x x x x]
  (f/dispose f)


Montoux Follow is available from

Add this to your :dependencies in project.clj:

[montoux/follow "1.0.0"]


Montoux is the global leader in pricing transformation for the life insurance industry. Our customers include several of the world's leading insurance providers and we are expanding our business in the United States and Asia, as well as Australia and New Zealand.


Copyright © 2018 Montoux Limited

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