(if-not test then)
(if-not test then else)
Evaluates test. If logical false, evaluates and returns then expr,
otherwise else expr, if supplied, else nil.
Source
(defmacro if-not
"Evaluates test. If logical false, evaluates and returns then expr,
otherwise else expr, if supplied, else nil."
{:added "1.0"}
([test then] `(if-not ~test ~then nil))
([test then else]
`(if (not ~test) ~then ~else)))