Samples for updating from a future

[gregorybleiker]

Following the thread on slack clojuredart I have tried to compile a sample using the 3 methods described. I could not figure out a good example for the atom holding a future as described by cgrand in the thread.

[dupuchba]

thanks a lot @gregorybleiker for your 1st contribution! it's greatly appreciated! I'll get back to you at the end of the day (testing this PR &so on)