If test is true, evaluates then with binding-form bound to the value of test, if not, yields else.

if-let.lisp

(defmacro if-let ((var test) then &optional else)
  "(if-let binding then else?)
  binding => binding-form test

  If test is true, evaluates then with binding-form bound to the value of
  test, if not, yields else"
  `(let ((,var ,test))
     (if ,var
       ,then
       ,else)))