Add lazy lists from the book

mceval/lazy-list.rkt

@@ -0,0 +1,41 @@
+;; Lisp code that can be evaluated by the lazy evaluator to implement
+;; lazy lists
+
+#lang sicp
+
+(#%provide lazy-lists-program)
+
+(define lazy-lists-program
+  '((define (cons x y)
+      (lambda (m) (m x y)))
+    
+    (define (car z)
+      (z (lambda (p q) p)))
+    
+    (define (cdr z)
+      (z (lambda (p q) q)))
+
+    (define (list-ref items n)
+      (if (= n 0) (car items)
+          (list-ref (cdr items)
+                    (- n 1))))
+
+    (define (map proc items)
+      (if (null? items) '()
+          (cons (proc (car items))
+                (map proc (cdr items)))))
+
+    (define (scale-list items factor)
+      (map (lambda (x) (* x factor)) items))
+
+    (define (add-lists list1 list2)
+      (cond ((null? list1) (car list2))
+            ((null? list2) (car list1))
+            (else
+             (cons (+ (car list1) (car list2))
+                   (add-lists (cdr list1)
+                              (cdr list2))))))
+
+    (define ones (cons 1 ones))
+
+    (define integers (cons 1 (add-lists ones integers)))))

mceval/leval.rkt

@@ -10,6 +10,7 @@
 (#%require "environment.rkt")
 (#%require "common.rkt")
 (#%require "special-forms.rkt")
+(#%require "lazy-list.rkt")
 
 (#%provide lazy-driver-loop
            lazy-eval-program)
@@ -83,6 +84,8 @@
 
 (define (lazy-driver-loop)
   (define env (setup-environment))
+  ;; Read in code to implement lazy lists
+  (eval-program lazy-lists-program actual-value user-print env)
   (define (driver-loop)
     (prompt-for-input input-prompt)
     (let ((input (read)))
@@ -94,6 +97,7 @@
 
 (define (lazy-eval-program program)
   (define env (setup-environment))
+  (eval-program lazy-lists-program actual-value user-print env)
   (eval-program program actual-value user-print env))
 
 ;;; Representing thunks