Clojure not nil check

After Clojure 1.6 you can use some?:

(some? :foo) => true
(some? nil) => false

This is useful, eg, as a predicate:

(filter some? [1 nil 2]) => (1 2)

Another way to define not-nil? would be using the complement function, which just inverts the truthyness of a boolean function:

(def not-nil? (complement nil?))

If you have several values to check then use not-any?:

user> (not-any? nil? [true 1 '()])
true
user> (not-any? nil? [true 1 nil])
false 

If you are not interested in distinguishing false from nil, you can just use the value as the condition:

(if value1
   "value1 is neither nil nor false"
   "value1 is nil or false")