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icncsx
icncsx

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Clojure 101 / operator precedence

#clojure #tutorial #functional

Surprise! I tricked you (πŸ˜†). There is no operator precedence in Clojure because there are no operators - only functions and arguments.

All functions evaluate left to right and inside out. Function first, then args.

(/ 1 2) (/ 500 20) (= "foo" "bar") (not true)
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Ok, that seems trivial. How about something more complicated?

(defn leap-year? [year] (or (and (= (rem year 4) 0) (> (rem year 100) 0)) (= (rem year 400) 0)))
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I'm telling you this is such an underrated feature of using Clojure. I can focus on memorizing the important stuff - not horrendously lengthy precedence tables such as this:

Alt Text

Now can you figure out what this does in JavaScript?

3 > 2 && 2 > 1
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Apparently, it returns true. I love you JavaScript, but we need a break... truly...

Warmly,
DH

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