Impelement till 4.5

misc/evaluator.scm

@@ -63,6 +63,8 @@
 (define (self-evaluating? exp)
   (cond ((number? exp) true)
         ((string? exp) true)
+        ((eq? exp #t) true)
+        ((eq? exp #f) true)
         (else false)))
 
 (define (variable? exp) (symbol? exp))