It's Probably Fine
to think in Clojure just a little bit
July 04, 2017
After reading most of Clojure for the Brave and True, I was embarrassed to draw a big, fat blank trying to write a dead simple mean function recently. Turns out I was overthinking it.
(defn mean
[xs]
(/ (apply + xs) (count xs)))
I kept wanting to consider each value separately in a loop or reducer instead of thinking of the collection as a whole. You can’t just + a collection in any other language I use. I hadn’t thought of the possibilities like this that prefix notation offers.
Repetition == Remembering
If I hadn’t been feeling so out of place in Clojureland, I would have realized my preferred JavaScript approach makes use of functional elements as well:
function mean(xs) {
const sum = xs.reduce((sum, x) => sum + x);
const count = xs.length;
return sum / count;
}
I’ve really grown to love reduce, map, and forEach on my JS arrays.
How about Java? Not sure I’m doing this idiomatically, but since I last used it in v6, Java’s gotten lambdas and streams. So I think that means it ends up a lot like the JavaScript implementation:
static long mean(Collection<Long> xs) {
long total = xs.stream().reduce(0l, (sum, x) -> sum + x);
int count = xs.size();
return total / count;
}
May I never stare blankly at an empty mean function body again.
I'm Trevor Farlow, a Denver-based software developer. They said "always be learning," so here I am.