Implement 5.23

misc/sicp-eceval.scm

@@ -68,6 +68,11 @@
    (list 'extend-environment extend-environment)
    (list 'lookup-variable-value lookup-variable-value)
    (list 'set-variable-value! set-variable-value!)
+   ;;5.23
+   (list 'cond? cond?)
+   (list 'cond->if cond->if)
+   (list 'let? let?)
+   (list 'let->combination let->combination)
    (list 'define-variable! define-variable!)
    (list 'primitive-procedure? primitive-procedure?)
    (list 'apply-primitive-procedure apply-primitive-procedure)
@@ -119,6 +124,10 @@ eval-dispatch
   (branch (label ev-definition))
   (test (op if?) (reg exp))
   (branch (label ev-if))
+  (test (op cond?) (reg exp))
+  (branch (label ev-cond))
+  (test (op let?) (reg exp))
+  (branch (label ev-let))
   (test (op lambda?) (reg exp))
   (branch (label ev-lambda))
   (test (op begin?) (reg exp))
@@ -228,8 +237,16 @@ ev-sequence-last-exp
   (restore continue)
   (goto (label eval-dispatch))
 
-;;;SECTION 5.4.3
+;;; ex-5.23
+ev-cond
+  (assign exp (op cond->if) (reg exp))
+  (goto (label eval-dispatch))
 
+ev-let
+  (assign exp (op let->combination) (reg exp))
+  (goto (label eval-dispatch))
+
+;;;SECTION 5.4.3
 ev-if
   (save exp)
   (save env)