State propagation via atoms. Usable in Clojure and ClojureScript.
Leiningen dependency:
[twinfoxcreations/fusion "0.1.0"]
(require '[fusion.core :refer [fuse]])
(def a (atom 1))
(def b (atom 2))
(def sum (fuse (+ @a @b)))
@sum ; 3
(reset! a 4)
(reset! b 5)
@sum ; 9
In this example, sum is a FusedAtom which, when dereferenced, returns the
sum of a and b.
Fused atoms are lazy: the body is not evaluated until it is dereferenced. Once evaluated, the value is stored for later.
Atoms dereferenced in the body are automatically watched for changes - if a
or b change, then sum is dirtied so it will recompute its value the next
time it is dereferenced.
For some problems, it can be nice to model state using a chain of connected atoms. Events that trigger updates in a source atom can automatically propagate through any dependent (fused) atoms.
Similar to ideas from Functional-Reactive Programming, though this library doesn't address the event side of things. State propagation only.
Actually, this is really just an excuse to practice test-driven development and library deployment. Hurray!