Hacker News Reader

Comment by dmichulke | Hacker News Reader

I always use `or` because it's IMO most readable:

    (or x 5) ;;=> returns x if x is not nil, else 5

E.g.,

    (-> {:a 1 :b 2}
        :c
        (or 5.5)
        inc)

View on HN

One problem with using or is if the key is associated with false, then it will be ignored in favour of the default. Keywords support a second argument which is the default to use on not-found so you can just write:

    (-> {:a 1 :b 2}
        (:c 5.5)
        inc)

> ;;=> returns x if x is nil, else 5

Should this be:

> ;;=> returns x if x is not nil, else 5

Corrected, thanks! (It was correct in the beginning but then I decided I need to improve it)

=> https://en.wiktionary.org/wiki/verschlimmbessern

`false` is not nil but `(let [x false] (or x 5))` evaluates to 5 ;)

yes! you have eliminated repeating yourself and returning nil. Other ways to do this very simple example:

`(some-> m :c (inc 5))`

there is no need to defend against nil values. Hickey has your back on built in functions.

Franky, this looks great and should be in the article :-)

Reply on news.ycombinator.com