Re: chain of transformations

Kaz Kylheku wrote:

(defun tree-find (needle haystack &key (test #'eql))
  (dolist (item haystack)
    (if (funcall test needle item)
      (return item)
      (when (consp item)
        (let ((find (tree-find needle item :test test)))
          (when find
            (return find)))))))

Gauche Scheme:

(define (tree-find needle haystack :optional (test equal?))
  (any
    (lambda (item)
      (if (test needle item)
        item
        (and (pair? item) (tree-find needle item test))))
    haystack))