Re: shootout: implementing an interpreter

B. Pym wrote:

Kent M. Pitman wrote:
 

(defun shrug (list)
  (loop for (x . sublist-and-more) on list
        for more = (member x sublist-and-more)
        when more
         collect `(g ,x ,(ldiff sublist-and-more more))))
=> SHRUG
 
(shrug '(a b c a d b d))
=> ((G A (B C)) (G B (C A D)) (G D (B)))

Gauche Scheme

Using recursion instead of looping and the symbol !
instead of the less distinctive G.

(define (shrug List)
  (if (pair? List)
    (let* ((x (pop! List)) (more (member x List)))
      (if more
        (cons `(! ,x ,(drop-right List (length more))) (shrug List))
        (shrug List)))
    ()))

(shrug '(a b c a d b d))
  ===>
((! a (b c)) (! b (c a d)) (! d (b)))