lazy special form sample

lazy_syntax.scm

(define-syntax lazy
  (syntax-rules ()
    ((lazy)
     (error "lazy requires (lazy s-expression)"))
    ((lazy s-exp)
     (let-syntax
         ((map
           (syntax-rules (%lazy-map)
             ((map)
              (error "map requires (map func lst ...)"))
             ((map func)
              (error "map requires (map func lst ...)"))
             ((map func       lst1)
              (%lazy-map func lst1))
             ((map func       lst1 lst2)
              (%lazy-map func lst1 lst2))
             ((map func       lst1 lst2 lst3)
              (%lazy-map func lst1 lst2 lst3))))
             
          (for-each
           (syntax-rules (%lazy-for-each)
             ((for-each)
              (error "for-each requires (for-each func lst ...)"))
             ((for-each func)
              (error "for-each requires (for-each func lst ...)"))
             ((for-each func       lst1)
              (%lazy-for-each func lst1))
             ((for-each func       lst1 lst2)
              (%lazy-for-each func lst1 lst2))
             ((for-each func       lst1 lst2 lst3)
              (%lazy-for-each func lst1 lst2 lst3))
             ))
          (filter
           (syntax-rules (%lazy-filter)
             ((filter)
              (error "filter requires (filter func lst ...)"))
             ((filter func)
              (error "filter requires (filter func lst ...)"))
             ((filter func       lst1)
              (%lazy-filter func lst1))
             ((filter func       lst1 lst2)
              (%lazy-filter func lst1 lst2))
             ((filter func       lst1 lst2 lst3)
              (%lazy-filter func lst1 lst2 lst3))
             )))
       s-exp))
    ((lazy s-exp other)
     (error "lazy requires (lazy s-expression)"))))