skeleton code

cm.rkt

@@ -0,0 +1,120 @@
+#lang racket
+
+
+;; Chapter 5.5 of the compiler
+
+
+;; compile: expression target linkage -> instruction-sequence
+(define (compile exp target linkage)
+  (cond
+    [(self-evaluating? exp)
+     (compile-self-evaluating exp target linkage)]
+    [(quoted? exp)
+     (compile-quoted exp target linkage)]
+    [(variable? exp)
+     (compile-variable exp target linkage)]
+    [(assignment? exp)
+     (compile-assignment exp target linkage)]
+    [(definition? exp)
+     (compile-definition exp target linkage)]
+    [(if? exp)
+     (compile-if exp target linkage)]
+    [(lambda? exp)
+     (compile-lambda exp target linkage)]
+    [(begin? exp)
+     (compile-sequence (begin-actions exp)
+                       target
+                       linkage)]
+    ;; skipping cond
+    [(application? exp)
+     (compile-application exp target linkage)]
+    [else
+     (error 'compile "Unknown expression type ~e" exp)]))
+    
+
+(define (compile-self-evaluating exp target linkage) (error))
+(define (compile-quoted exp target linkage) (error))
+(define (compile-variable exp target linkage) (error))
+(define (compile-assignment exp target linkage) (error))
+(define (compile-definition exp target linkage) (error))
+(define (compile-if exp target linkage) (error))
+(define (compile-lambda exp target linkage) (error))
+(define (compile-sequence seq target linkage) (error))
+(define (compile-application exp target linkage) (error))
+
+
+
+(define (self-evaluating? exp)
+  (cond
+    [(number? exp) #t]
+    [(string? exp) #t]
+    [else #f]))
+
+(define (variable? exp) (symbol? exp))
+
+(define (quoted? exp) (tagged-list? exp 'quote))
+
+(define (tagged-list? exp tag)
+  (if (pair? exp)
+      (eq? (car exp) tag)
+      #f))
+
+(define (assignment? exp)
+  (tagged-list? exp 'set!))
+(define (assignment-variable exp) (cadr exp))
+(define (assignment-value exp) (caddr exp))
+
+(define (definition? exp)
+  (tagged-list? exp 'define))
+(define (definiiton-variable exp)
+  (if (symbol? (cadr exp))
+      (cadr exp)
+      (caadr exp)))
+(define (definition-value exp)
+  (if (symbol? (cadr exp))
+      (caddr exp)
+      (make-lambda (cdadr exp)
+                   (cddr exp))))
+
+(define (lambda? exp)
+  (tagged-list? exp 'lambda))
+(define (lambda-parameters exp) (cadr exp))
+(define (lambda-body exp) (cddr exp))
+
+(define (make-lambda parameters body)
+  (cons 'lambda (cons parameters body)))
+
+(define (if? exp)
+  (tagged-list? exp 'if))
+(define (if-predicate exp)
+  (cadr exp))
+(define (if-consequent exp)
+  (caddr exp))
+(define (if-alternative exp)
+  (if (not (null? (cdddr exp)))
+      (cadddr exp)
+      'false))
+
+(define (begin? exp)
+  (tagged-list? exp 'begin))
+(define (begin-actions exp) (cdr exp))
+(define (last-exp? seq) (null? (cdr seq)))
+(define (first-exp seq) (car seq))
+(define (rest-exps seq) (cdr seq))
+
+(define (sequence->exp seq)
+  (cond
+    [(null? seq) '()]
+    [(last-exp? seq)
+     (first-exp seq)]
+    [else (make-begin seq)]))
+
+(define (make-begin seq) (cons 'begin seq))
+
+
+(define (application? exp) (pair? exp))
+(define (operator exp) (car exp))
+(define (operands exp) (cdr exp))
+(define (no-operands? ops) (null? ops))
+(define (first-operand ops) (car ops))
+(define (rest-operands ops) (cdr ops))