Using Idiomatic Clojure, Part 1 - comp

As I read the Clojure code of others, I come across better ways to write my own code. Today’s example comes from The Joy of Clojure by Michael Fogus and Chris Houser.

I often find myself writing anonymous functions along the lines of

#(not (vector? %))

to act as filters in various places (filter, for, take-while, etc.). I always thought it looked a bit gnarly like that. Fortunately, there is a better way, using the comp function.

According to the documentation string, comp takes a number of functions and returns a new function that is the composition of all of them. I’ve used comp a few other places before, but for some reason, it didn’t “click” that I could use it in this situation, too. With it, the above code transforms into the much cleaner-looking

(comp not vector?)

Looks much better without the anonymous function trappings, yes?

Update: I just came back to this post after a long time… Now I probably wouldn’t even use comp here, opting instead for

(complement vector?)

It keeps getting shorter!

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