;;;; srfi-42-sequences.scm - By Thomas Chust


(module sequence-comprehensions (:seq)

(import scheme (chicken base) srfi-42
        (rename sequences (index iterator-index)))

(define-syntax :seq
  (syntax-rules (index)
    [(:seq cc var (index idx) arg)
     (:do cc
	  (let ([seq arg]))
	  ([itr (iterator seq)])
	  (not (at-end? itr))
	  (let ([var (elt seq itr)] [idx (iterator-index itr)]))
	  #t
	  ((advance! itr)))]
    [(:seq cc var (index idx) arg ...)
     (:seq cc var (index idx) (append (coerce '() arg) ...))]
    [(:seq cc var arg)
     (:do cc
	  (let ([seq arg]))
	  ([itr (iterator seq)])
	  (not (at-end? itr))
	  (let ([var (elt seq itr)]))
	  #t
	  ((advance! itr)))]
    [(:seq cc var arg ...)
     (:seq cc var (append (coerce '() arg) ...))]))


)