Question

In Common Lisp you use the (null x) function to check for empty lists and nil values.

Most logically this maps to

(or (nil?  x) (= '() x))

In clojure. Can someone suggest a more idiomatic way to do it in Clojure?

Answer 1

To get the same result for an empty list in Clojure as you do in Common Lisp, use the empty? function. This function is in the core library: no imports are necessary.

It is also a predicate, and suffixed with a ?, making it a little clearer what exactly you’re doing in the code.

=> (empty? '())
true
=> (empty? '(1 2))
false
=> (empty? nil)
true

As j-g faustus already noted, seq can be used for a similar effect.