ANSI Common Lisp   6 Iteration   6.1 The LOOP Facility   6.1.3 Value Accumulation Clauses

6.1.3.1 Examples of COLLECT clause

;; Collect all the symbols in a list.
 (loop for i in '(bird 3 4 turtle (1 . 4) horse cat)
       when (symbolp i) collect i)
 (BIRD TURTLE HORSE CAT)
 
;; Collect and return odd numbers.
 (loop for i from 1 to 10
       if (oddp i) collect i)
 (1 3 5 7 9)
 
;; Collect items into local variable, but don't return them.
 (loop for i in '(a b c d) by #'cddr
       collect i into my-list
       finally (print my-list))
(A C) 
  NIL