destructuring-bind

destructuring-bind Macro

Syntax:

destructuring-bind lambda-list expression {declaration}* {form}*

→ {result}*

Arguments and Values:

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.

Description:

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).

Examples:

(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) 
Data and Control 

Exceptional Situations:

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

See Also:

macrolet, defmacro

Expanded Reference: destructuring-bind

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