lambda-list — a destructuring lambda list.

expression — a form.

declaration — a declare expression; not evaluated.

forms — an implicit progn.

results — the values returned by the forms.

destructuring-bind binds the variables specified in lambda-list to the corresponding values in the tree structure resulting from the evaluation of expression; then destructuring-bind evaluates forms.

The lambda-list supports destructuring as described in Section 3.4.5 (Destructuring Lambda Lists).

(defun iota (n) (loop for i from 1 to n collect i))       ;helper 
(destructuring-bind ((a &optional (b 'bee)) one two three) 
    `((alpha) ,@(iota 3)) 
  (list a b three two one)) → (ALPHA BEE 3 2 1)

If the result of evaluating the expression does not match the destructuring pattern, an error of type error should be signaled.

macrolet, defmacro