hygenic-let.scm

(define-syntax let
  (rsc-macro-transformer
   (lambda (form mac-env)
     (if (symbol? (cadr form))
	 ((lambda (name bindings body)
	    (list (make-syntactic-closure mac-env '() 'let)
		  '()
		  (list (make-syntactic-closure mac-env '() 'define)
			name
			(cons (make-syntactic-closure mac-env '() 'lambda)
			      (cons (map car bindings)
				    body)))
		  (cons name (map cadr bindings))))
	  (cadr  form)
	  (caddr form)
	  (cdddr form))
	 ((lambda (bindings body)
	    (cons (cons (make-syntactic-closure mac-env '() 'lambda)
			(cons (map car bindings)
			      body))
		  (map cadr bindings)))
	  (cadr form)
	  (cddr form))))))