chickadee » alist-lib » alist-set!

Destructively set a key-value association.

alist

The alist in which to set

key

The key to set

value

The value to associate with the key

(define-syntax
  alist-set!
  (lambda (expression rename compare)
    (match expression
           ((_ variable key value)
            (let ((%if (rename 'if))
                  (%null? (rename 'null?))
                  (%set! (rename 'set!))
                  (%list (rename 'list))
                  (%cons (rename 'cons))
                  (%alist-prepend! (rename 'alist-prepend!)))
              `(,%if
                (,%null? ,variable)
                (,%set! ,variable (,%list (,%cons ,key ,value)))
                (,%alist-prepend! ,variable ,key ,value)))))))