;;; let.ss

(load "/u/c311/ss/env.ss")

(define <let-language> ; EOPL Figure 5.3.2
  (class ()
    (base <env-language>)
    (base-inst-vars <exps> <extended-environment> test-clauses)
    (base-methods (base-parse parse))
    (base-init)
    (inst-vars
      (define <let>
	(class (formals exps body)
	  (base <syntax>)
	  (inst-vars formals exps body)
	  (methods
	    (define eval
	      (method (env)
		(eval body
		  (<extended-environment> env formals (eval exps env)))))
	    (define unparse
	      (method ()
		(list 'let
		  (map list formals (unparse exps))
		  (unparse body)))))))
      (set! test-clauses
	(append
	  '(((let ((x 3) (y 4)) (+ x y)) 7))
	  test-clauses)))
    (methods
      (define name
	(method () 'let))
      (define parse
	(method (datum)
	  (form-case datum
	    (let (decls body)
	      (<let> (map car decls)
		(<exps> (map (lambda (datum) (parse this datum))
			  (map cadr decls)))
		(parse this body)))
	    (else (base-parse this datum))))))))