*** ch4-mceval.scm.orig	1996-09-05 03:17:21.000000000 +0900
--- ch4-mceval.scm	2005-01-24 07:09:49.000000000 +0900
***************
*** 16,22 ****
  
  ;;;SECTION 4.1.1
  
! (define (eval exp env)
    (cond ((self-evaluating? exp) exp)
          ((variable? exp) (lookup-variable-value exp env))
          ((quoted? exp) (text-of-quotation exp))
--- 16,22 ----
  
  ;;;SECTION 4.1.1
  
! (define (myeval exp env)
    (cond ((self-evaluating? exp) exp)
          ((variable? exp) (lookup-variable-value exp env))
          ((quoted? exp) (text-of-quotation exp))
***************
*** 29,42 ****
                           env))
          ((begin? exp) 
           (eval-sequence (begin-actions exp) env))
!         ((cond? exp) (eval (cond->if exp) env))
          ((application? exp)
!          (apply (eval (operator exp) env)
                  (list-of-values (operands exp) env)))
          (else
           (error "Unknown expression type -- EVAL" exp))))
  
! (define (apply procedure arguments)
    (cond ((primitive-procedure? procedure)
           (apply-primitive-procedure procedure arguments))
          ((compound-procedure? procedure)
--- 29,42 ----
                           env))
          ((begin? exp) 
           (eval-sequence (begin-actions exp) env))
!         ((cond? exp) (myeval (cond->if exp) env))
          ((application? exp)
!          (myapply (myeval (operator exp) env)
                  (list-of-values (operands exp) env)))
          (else
           (error "Unknown expression type -- EVAL" exp))))
  
! (define (myapply procedure arguments)
    (cond ((primitive-procedure? procedure)
           (apply-primitive-procedure procedure arguments))
          ((compound-procedure? procedure)
***************
*** 54,81 ****
  (define (list-of-values exps env)
    (if (no-operands? exps)
        '()
!       (cons (eval (first-operand exps) env)
              (list-of-values (rest-operands exps) env))))
  
  (define (eval-if exp env)
!   (if (true? (eval (if-predicate exp) env))
!       (eval (if-consequent exp) env)
!       (eval (if-alternative exp) env)))
  
  (define (eval-sequence exps env)
!   (cond ((last-exp? exps) (eval (first-exp exps) env))
!         (else (eval (first-exp exps) env)
                (eval-sequence (rest-exps exps) env))))
  
  (define (eval-assignment exp env)
    (set-variable-value! (assignment-variable exp)
!                        (eval (assignment-value exp) env)
                         env)
    'ok)
  
  (define (eval-definition exp env)
    (define-variable! (definition-variable exp)
!                     (eval (definition-value exp) env)
                      env)
    'ok)
  
--- 54,81 ----
  (define (list-of-values exps env)
    (if (no-operands? exps)
        '()
!       (cons (myeval (first-operand exps) env)
              (list-of-values (rest-operands exps) env))))
  
  (define (eval-if exp env)
!   (if (true? (myeval (if-predicate exp) env))
!       (myeval (if-consequent exp) env)
!       (myeval (if-alternative exp) env)))
  
  (define (eval-sequence exps env)
!   (cond ((last-exp? exps) (myeval (first-exp exps) env))
!         (else (myeval (first-exp exps) env)
                (eval-sequence (rest-exps exps) env))))
  
  (define (eval-assignment exp env)
    (set-variable-value! (assignment-variable exp)
!                        (myeval (assignment-value exp) env)
                         env)
    'ok)
  
  (define (eval-definition exp env)
    (define-variable! (definition-variable exp)
!                     (myeval (definition-value exp) env)
                      env)
    'ok)
  
***************
*** 330,336 ****
  (define (driver-loop)
    (prompt-for-input input-prompt)
    (let ((input (read)))
!     (let ((output (eval input the-global-environment)))
        (announce-output output-prompt)
        (user-print output)))
    (driver-loop))
--- 330,336 ----
  (define (driver-loop)
    (prompt-for-input input-prompt)
    (let ((input (read)))
!     (let ((output (myeval input the-global-environment)))
        (announce-output output-prompt)
        (user-print output)))
    (driver-loop))