1 665c255d 2023-08-04 jrmu (define (eval exp env)
2 665c255d 2023-08-04 jrmu (cond ((self-evaluating? exp) exp)
3 665c255d 2023-08-04 jrmu ((variable? exp) (lookup-variable-value exp env))
4 665c255d 2023-08-04 jrmu ((quoted? exp) (text-of-quotation exp))
5 665c255d 2023-08-04 jrmu ((assignment? exp) (eval-assignment exp env))
6 665c255d 2023-08-04 jrmu ((definition? exp) (eval-definition exp env))
7 665c255d 2023-08-04 jrmu ((if? exp) (eval-if exp env))
8 665c255d 2023-08-04 jrmu ((and? exp) (eval-and exp env))
9 665c255d 2023-08-04 jrmu ((or? exp) (eval-or exp env))
10 665c255d 2023-08-04 jrmu ((lambda? exp)
11 665c255d 2023-08-04 jrmu (make-procedure (lambda-parameters exp)
12 665c255d 2023-08-04 jrmu (lambda-body exp)
14 665c255d 2023-08-04 jrmu ((begin? exp)
15 665c255d 2023-08-04 jrmu (eval-sequence (begin-actions exp) env))
16 665c255d 2023-08-04 jrmu ((cond? exp) (eval (cond->if exp) env))
17 665c255d 2023-08-04 jrmu ((let? exp) (eval (let->combination exp) env))
18 665c255d 2023-08-04 jrmu ((let*? exp) (eval (let*->nested-lets exp) env))
19 665c255d 2023-08-04 jrmu ((named-let? exp) (eval (named-let->combination exp) env))
20 665c255d 2023-08-04 jrmu ((do? exp) (eval (do->combination exp) env))
21 665c255d 2023-08-04 jrmu ((application? exp)
22 665c255d 2023-08-04 jrmu (apply (eval (operator exp) env)
23 665c255d 2023-08-04 jrmu (list-of-values (operands exp) env)))
25 665c255d 2023-08-04 jrmu (error "Unknown expression type -- EVAL" exp))))
26 665c255d 2023-08-04 jrmu (define (apply procedure arguments)
27 665c255d 2023-08-04 jrmu (cond ((primitive-procedure? procedure)
28 665c255d 2023-08-04 jrmu (apply-primitive-procedure procedure arguments))
29 665c255d 2023-08-04 jrmu ((compound-procedure? procedure)
30 665c255d 2023-08-04 jrmu (eval-sequence
31 665c255d 2023-08-04 jrmu (procedure-body procedure)
32 665c255d 2023-08-04 jrmu (extend-environment
33 665c255d 2023-08-04 jrmu (procedure-parameters procedure)
35 665c255d 2023-08-04 jrmu (procedure-environment procedure))))
38 665c255d 2023-08-04 jrmu "Unknown procedure type -- APPLY" procedure))))
40 665c255d 2023-08-04 jrmu (define (list-of-values exps env)
41 665c255d 2023-08-04 jrmu (if (no-operands? exps)
43 665c255d 2023-08-04 jrmu (cons (eval (first-operand exps) env)
44 665c255d 2023-08-04 jrmu (list-of-values (rest-operands exps) env))))
46 665c255d 2023-08-04 jrmu (define (tagged-list? exp tag)
47 665c255d 2023-08-04 jrmu (if (pair? exp)
48 665c255d 2023-08-04 jrmu (eq? (car exp) tag)
51 665c255d 2023-08-04 jrmu ;; self-evaluating/variable/quoted
52 665c255d 2023-08-04 jrmu (define (self-evaluating? exp)
53 665c255d 2023-08-04 jrmu (cond ((number? exp) true)
54 665c255d 2023-08-04 jrmu ((string? exp) true)
55 665c255d 2023-08-04 jrmu (else false)))
56 665c255d 2023-08-04 jrmu (define (variable? exp) (symbol? exp))
57 665c255d 2023-08-04 jrmu (define (quoted? exp)
58 665c255d 2023-08-04 jrmu (tagged-list? exp 'quote))
59 665c255d 2023-08-04 jrmu (define (text-of-quotation exp) (cadr exp))
61 665c255d 2023-08-04 jrmu ;; assignment/definition
62 665c255d 2023-08-04 jrmu (define (assignment? exp)
63 665c255d 2023-08-04 jrmu (tagged-list? exp 'set!))
64 665c255d 2023-08-04 jrmu (define (assignment-variable exp) (cadr exp))
65 665c255d 2023-08-04 jrmu (define (assignment-value exp) (caddr exp))
66 665c255d 2023-08-04 jrmu (define (definition? exp)
67 665c255d 2023-08-04 jrmu (tagged-list? exp 'define))
68 665c255d 2023-08-04 jrmu (define (definition-variable exp)
69 665c255d 2023-08-04 jrmu (if (symbol? (cadr exp))
71 665c255d 2023-08-04 jrmu (caadr exp)))
72 665c255d 2023-08-04 jrmu (define (definition-value exp)
73 665c255d 2023-08-04 jrmu (if (symbol? (cadr exp))
75 665c255d 2023-08-04 jrmu (make-lambda (cdadr exp) ; formal parameters
76 665c255d 2023-08-04 jrmu (cddr exp)))) ; body
77 665c255d 2023-08-04 jrmu (define (eval-assignment exp env)
78 665c255d 2023-08-04 jrmu (set-variable-value! (assignment-variable exp)
79 665c255d 2023-08-04 jrmu (eval (assignment-value exp) env)
82 665c255d 2023-08-04 jrmu (define (eval-definition exp env)
83 665c255d 2023-08-04 jrmu (define-variable! (definition-variable exp)
84 665c255d 2023-08-04 jrmu (eval (definition-value exp) env)
87 665c255d 2023-08-04 jrmu (define (make-definition var val)
88 665c255d 2023-08-04 jrmu `(define ,var ,val))
91 665c255d 2023-08-04 jrmu ;; if/and/or
92 665c255d 2023-08-04 jrmu (define (if? exp) (tagged-list? exp 'if))
93 665c255d 2023-08-04 jrmu (define (if-predicate exp) (cadr exp))
94 665c255d 2023-08-04 jrmu (define (if-consequent exp) (caddr exp))
95 665c255d 2023-08-04 jrmu (define (if-alternative exp)
96 665c255d 2023-08-04 jrmu (if (not (null? (cdddr exp)))
97 665c255d 2023-08-04 jrmu (cadddr exp)
99 665c255d 2023-08-04 jrmu (define (make-if predicate consequent alternative)
100 665c255d 2023-08-04 jrmu (list 'if predicate consequent alternative))
101 665c255d 2023-08-04 jrmu (define (eval-if exp env)
102 665c255d 2023-08-04 jrmu (if (true? (eval (if-predicate exp) env))
103 665c255d 2023-08-04 jrmu (eval (if-consequent exp) env)
104 665c255d 2023-08-04 jrmu (eval (if-alternative exp) env)))
106 665c255d 2023-08-04 jrmu (define (and? exp)
107 665c255d 2023-08-04 jrmu (tagged-list? exp 'and))
108 665c255d 2023-08-04 jrmu (define (and-clauses exp)
110 665c255d 2023-08-04 jrmu (define (or? exp)
111 665c255d 2023-08-04 jrmu (tagged-list? exp 'or))
112 665c255d 2023-08-04 jrmu (define (or-clauses exp)
114 665c255d 2023-08-04 jrmu (define (eval-and exp env)
115 665c255d 2023-08-04 jrmu (define (eval-clauses clauses)
116 665c255d 2023-08-04 jrmu (cond ((null? clauses) true)
117 665c255d 2023-08-04 jrmu ((null? (cdr clauses)) (eval (car clauses) env))
118 665c255d 2023-08-04 jrmu (else (and (eval (car clauses) env)
119 665c255d 2023-08-04 jrmu (eval-clauses (cdr clauses))))))
120 665c255d 2023-08-04 jrmu (eval-clauses (and-clauses exp)))
121 665c255d 2023-08-04 jrmu (define (eval-or exp env)
122 665c255d 2023-08-04 jrmu (define (eval-clauses clauses)
123 665c255d 2023-08-04 jrmu (if (null? clauses)
125 665c255d 2023-08-04 jrmu (or (eval (car clauses) env)
126 665c255d 2023-08-04 jrmu (eval-clauses (cdr clauses)))))
127 665c255d 2023-08-04 jrmu (eval-clauses (or-clauses exp)))
130 665c255d 2023-08-04 jrmu ;; lambda/let/let*
131 665c255d 2023-08-04 jrmu (define (lambda? exp) (tagged-list? exp 'lambda))
132 665c255d 2023-08-04 jrmu (define (lambda-parameters exp) (cadr exp))
133 665c255d 2023-08-04 jrmu (define (lambda-body exp) (cddr exp))
134 665c255d 2023-08-04 jrmu (define (make-lambda parameters body)
135 665c255d 2023-08-04 jrmu (cons 'lambda (cons parameters body)))
137 665c255d 2023-08-04 jrmu (define (make-let vars vals body)
139 665c255d 2023-08-04 jrmu (cons (map list vars vals)
141 665c255d 2023-08-04 jrmu (define (let? exp)
142 665c255d 2023-08-04 jrmu (and (tagged-list? exp 'let)
143 665c255d 2023-08-04 jrmu (not (symbol? (cadr exp)))))
144 665c255d 2023-08-04 jrmu (define (let-vars exp)
145 665c255d 2023-08-04 jrmu (map car (cadr exp)))
146 665c255d 2023-08-04 jrmu (define (let-vals exp)
147 665c255d 2023-08-04 jrmu (map cadr (cadr exp)))
148 665c255d 2023-08-04 jrmu (define (let-body exp)
149 665c255d 2023-08-04 jrmu (cddr exp))
150 665c255d 2023-08-04 jrmu (define (let->combination exp)
151 665c255d 2023-08-04 jrmu (make-application (make-lambda (let-vars exp) (let-body exp))
152 665c255d 2023-08-04 jrmu (let-vals exp)))
153 665c255d 2023-08-04 jrmu (define (named-let? exp)
154 665c255d 2023-08-04 jrmu (and (tagged-list? exp 'let)
155 665c255d 2023-08-04 jrmu (symbol? (cadr exp))))
156 665c255d 2023-08-04 jrmu (define (named-let-name exp)
157 665c255d 2023-08-04 jrmu (cadr exp))
158 665c255d 2023-08-04 jrmu (define (named-let-vars exp)
159 665c255d 2023-08-04 jrmu (map car (caddr exp)))
160 665c255d 2023-08-04 jrmu (define (named-let-vals exp)
161 665c255d 2023-08-04 jrmu (map cadr (caddr exp)))
162 665c255d 2023-08-04 jrmu (define (named-let-body exp)
163 665c255d 2023-08-04 jrmu (cdddr exp))
164 665c255d 2023-08-04 jrmu (define (named-let->combination exp)
165 665c255d 2023-08-04 jrmu (sequence->exp
166 665c255d 2023-08-04 jrmu (list (make-definition (named-let-name exp)
167 665c255d 2023-08-04 jrmu (make-lambda (named-let-vars exp)
168 665c255d 2023-08-04 jrmu (named-let-body exp)))
169 665c255d 2023-08-04 jrmu (make-application (named-let-name exp)
170 665c255d 2023-08-04 jrmu (named-let-vals exp)))))
171 665c255d 2023-08-04 jrmu (define (make-named-let name vars vals body)
174 665c255d 2023-08-04 jrmu (cons (map list vars vals)
177 665c255d 2023-08-04 jrmu (define (make-application op args)
178 665c255d 2023-08-04 jrmu (cons op args))
180 665c255d 2023-08-04 jrmu (define (let*? exp)
181 665c255d 2023-08-04 jrmu (tagged-list? exp 'let*))
182 665c255d 2023-08-04 jrmu (define let*-vars let-vars)
183 665c255d 2023-08-04 jrmu (define let*-vals let-vals)
184 665c255d 2023-08-04 jrmu (define let*-body let-body)
185 665c255d 2023-08-04 jrmu (define (let*->nested-lets exp)
186 665c255d 2023-08-04 jrmu (define (expand-lets vars vals)
187 665c255d 2023-08-04 jrmu (if (null? (cdr vars))
188 665c255d 2023-08-04 jrmu (make-let (list (car vars))
189 665c255d 2023-08-04 jrmu (list (car vals))
190 665c255d 2023-08-04 jrmu (let*-body exp))
191 665c255d 2023-08-04 jrmu (make-let (list (car vars))
192 665c255d 2023-08-04 jrmu (list (car vals))
193 665c255d 2023-08-04 jrmu (list (expand-lets (cdr vars) (cdr vals))))))
194 665c255d 2023-08-04 jrmu (let ((vars (let*-vars exp))
195 665c255d 2023-08-04 jrmu (vals (let*-vals exp)))
196 665c255d 2023-08-04 jrmu (if (null? vars)
197 665c255d 2023-08-04 jrmu (sequence->exp (let*-body exp))
198 665c255d 2023-08-04 jrmu (expand-lets vars vals))))
201 665c255d 2023-08-04 jrmu (define (do? exp)
202 665c255d 2023-08-04 jrmu (tagged-list? exp 'do))
203 665c255d 2023-08-04 jrmu (define (do-vars exp)
204 665c255d 2023-08-04 jrmu (map car (cadr exp)))
205 665c255d 2023-08-04 jrmu (define (do-inits exp)
206 665c255d 2023-08-04 jrmu (map cadr (cadr exp)))
207 665c255d 2023-08-04 jrmu (define (do-steps exp)
208 665c255d 2023-08-04 jrmu (map (lambda (var-init-step)
209 665c255d 2023-08-04 jrmu (if (null? (cddr var-init-step))
210 665c255d 2023-08-04 jrmu (car var-init-step)
211 665c255d 2023-08-04 jrmu (caddr var-init-step)))
212 665c255d 2023-08-04 jrmu (cadr exp)))
213 665c255d 2023-08-04 jrmu (define (do-test exp)
214 665c255d 2023-08-04 jrmu (caaddr exp))
215 665c255d 2023-08-04 jrmu (define (do-expressions exp)
216 665c255d 2023-08-04 jrmu (if (null? (cdaddr exp))
217 665c255d 2023-08-04 jrmu (caddr exp)
218 665c255d 2023-08-04 jrmu (cdaddr exp)))
219 665c255d 2023-08-04 jrmu (define (do-commands exp)
220 665c255d 2023-08-04 jrmu (cdddr exp))
221 665c255d 2023-08-04 jrmu (define (do->combination exp)
222 665c255d 2023-08-04 jrmu (make-named-let
224 665c255d 2023-08-04 jrmu (do-vars exp)
225 665c255d 2023-08-04 jrmu (do-inits exp)
228 665c255d 2023-08-04 jrmu (do-test exp)
229 665c255d 2023-08-04 jrmu (sequence->exp (do-expressions exp))
230 665c255d 2023-08-04 jrmu (sequence->exp
231 665c255d 2023-08-04 jrmu (append (do-commands exp)
232 665c255d 2023-08-04 jrmu (list (make-application
234 665c255d 2023-08-04 jrmu (do-steps exp)))))))))
237 665c255d 2023-08-04 jrmu ;; begin/sequence
238 665c255d 2023-08-04 jrmu (define (begin? exp) (tagged-list? exp 'begin))
239 665c255d 2023-08-04 jrmu (define (begin-actions exp) (cdr exp))
240 665c255d 2023-08-04 jrmu (define (last-exp? seq) (null? (cdr seq)))
241 665c255d 2023-08-04 jrmu (define (first-exp seq) (car seq))
242 665c255d 2023-08-04 jrmu (define (rest-exps seq) (cdr seq))
243 665c255d 2023-08-04 jrmu (define (sequence->exp seq)
244 665c255d 2023-08-04 jrmu (cond ((null? seq) seq)
245 665c255d 2023-08-04 jrmu ((last-exp? seq) (first-exp seq))
246 665c255d 2023-08-04 jrmu (else (make-begin seq))))
247 665c255d 2023-08-04 jrmu (define (make-begin seq) (cons 'begin seq))
248 665c255d 2023-08-04 jrmu (define (eval-sequence exps env)
249 665c255d 2023-08-04 jrmu (cond ((last-exp? exps) (eval (first-exp exps) env))
250 665c255d 2023-08-04 jrmu (else (eval (first-exp exps) env)
251 665c255d 2023-08-04 jrmu (eval-sequence (rest-exps exps) env))))
253 665c255d 2023-08-04 jrmu ;; application
254 665c255d 2023-08-04 jrmu (define (application? exp) (pair? exp))
255 665c255d 2023-08-04 jrmu (define (operator exp) (car exp))
256 665c255d 2023-08-04 jrmu (define (operands exp) (cdr exp))
257 665c255d 2023-08-04 jrmu (define (no-operands? ops) (null? ops))
258 665c255d 2023-08-04 jrmu (define (first-operand ops) (car ops))
259 665c255d 2023-08-04 jrmu (define (rest-operands ops) (cdr ops))
262 665c255d 2023-08-04 jrmu (define (cond? exp) (tagged-list? exp 'cond))
263 665c255d 2023-08-04 jrmu (define (cond-clauses exp) (cdr exp))
264 665c255d 2023-08-04 jrmu (define (cond-else-clause? clause)
265 665c255d 2023-08-04 jrmu (eq? (cond-predicate clause) 'else))
266 665c255d 2023-08-04 jrmu (define (cond-predicate clause) (car clause))
267 665c255d 2023-08-04 jrmu (define (cond-actions clause) (cdr clause))
268 665c255d 2023-08-04 jrmu (define (cond-extended-clause? clause)
269 665c255d 2023-08-04 jrmu (and (not (null? (cdr clause))) (eq? (cadr clause) '=>)))
270 665c255d 2023-08-04 jrmu (define (cond-extended-proc clause)
271 665c255d 2023-08-04 jrmu (caddr clause))
272 665c255d 2023-08-04 jrmu (define (cond->if exp)
273 665c255d 2023-08-04 jrmu (expand-clauses (cond-clauses exp)))
274 665c255d 2023-08-04 jrmu (define (expand-clauses clauses)
275 665c255d 2023-08-04 jrmu (if (null? clauses)
276 665c255d 2023-08-04 jrmu 'false ; no else clause
277 665c255d 2023-08-04 jrmu (let ((first (car clauses))
278 665c255d 2023-08-04 jrmu (rest (cdr clauses)))
279 665c255d 2023-08-04 jrmu (if (cond-else-clause? first)
280 665c255d 2023-08-04 jrmu (if (null? rest)
281 665c255d 2023-08-04 jrmu (sequence->exp (cond-actions first))
282 665c255d 2023-08-04 jrmu (error "ELSE clause isn't last -- COND->IF"
284 665c255d 2023-08-04 jrmu (if (cond-extended-clause? first)
285 665c255d 2023-08-04 jrmu (make-if (cond-predicate first)
286 665c255d 2023-08-04 jrmu (make-application
287 665c255d 2023-08-04 jrmu (cond-extended-proc first)
288 665c255d 2023-08-04 jrmu (list (cond-predicate first)))
289 665c255d 2023-08-04 jrmu (expand-clauses rest))
290 665c255d 2023-08-04 jrmu (make-if (cond-predicate first)
291 665c255d 2023-08-04 jrmu (sequence->exp (cond-actions first))
292 665c255d 2023-08-04 jrmu (expand-clauses rest)))))))
293 665c255d 2023-08-04 jrmu (define (true? x)
294 665c255d 2023-08-04 jrmu (not (eq? x false)))
295 665c255d 2023-08-04 jrmu (define (false? x)
296 665c255d 2023-08-04 jrmu (eq? x false))
298 665c255d 2023-08-04 jrmu ;; procedure
299 665c255d 2023-08-04 jrmu (define (make-procedure parameters body env)
300 665c255d 2023-08-04 jrmu (list 'procedure parameters body env))
301 665c255d 2023-08-04 jrmu (define (compound-procedure? p)
302 665c255d 2023-08-04 jrmu (tagged-list? p 'procedure))
303 665c255d 2023-08-04 jrmu (define (procedure-parameters p) (cadr p))
304 665c255d 2023-08-04 jrmu (define (procedure-body p) (caddr p))
305 665c255d 2023-08-04 jrmu (define (procedure-environment p) (cadddr p))
307 665c255d 2023-08-04 jrmu ;; environment
308 665c255d 2023-08-04 jrmu (define (enclosing-environment env) (cdr env))
309 665c255d 2023-08-04 jrmu (define (first-frame env) (car env))
310 665c255d 2023-08-04 jrmu (define the-empty-environment '())
311 665c255d 2023-08-04 jrmu (define (make-frame variables values)
312 665c255d 2023-08-04 jrmu (cons variables values))
313 665c255d 2023-08-04 jrmu (define (frame-variables frame) (car frame))
314 665c255d 2023-08-04 jrmu (define (frame-values frame) (cdr frame))
315 665c255d 2023-08-04 jrmu (define (add-binding-to-frame! var val frame)
316 665c255d 2023-08-04 jrmu (set-car! frame (cons var (car frame)))
317 665c255d 2023-08-04 jrmu (set-cdr! frame (cons val (cdr frame))))
318 665c255d 2023-08-04 jrmu (define (extend-environment vars vals base-env)
319 665c255d 2023-08-04 jrmu (if (= (length vars) (length vals))
320 665c255d 2023-08-04 jrmu (cons (make-frame vars vals) base-env)
321 665c255d 2023-08-04 jrmu (if (< (length vars) (length vals))
322 665c255d 2023-08-04 jrmu (error "Too many arguments supplied" vars vals)
323 665c255d 2023-08-04 jrmu (error "Too few arguments supplied" vars vals))))
324 665c255d 2023-08-04 jrmu (define (lookup-variable-value var env)
325 665c255d 2023-08-04 jrmu (define (env-loop env)
326 665c255d 2023-08-04 jrmu (define (scan vars vals)
327 665c255d 2023-08-04 jrmu (cond ((null? vars)
328 665c255d 2023-08-04 jrmu (env-loop (enclosing-environment env)))
329 665c255d 2023-08-04 jrmu ((eq? var (car vars))
330 665c255d 2023-08-04 jrmu (car vals))
331 665c255d 2023-08-04 jrmu (else (scan (cdr vars) (cdr vals)))))
332 665c255d 2023-08-04 jrmu (if (eq? env the-empty-environment)
333 665c255d 2023-08-04 jrmu (error "Unbound variable" var)
334 665c255d 2023-08-04 jrmu (let ((frame (first-frame env)))
335 665c255d 2023-08-04 jrmu (scan (frame-variables frame)
336 665c255d 2023-08-04 jrmu (frame-values frame)))))
337 665c255d 2023-08-04 jrmu (env-loop env))
338 665c255d 2023-08-04 jrmu (define (set-variable-value! var val env)
339 665c255d 2023-08-04 jrmu (define (env-loop env)
340 665c255d 2023-08-04 jrmu (define (scan vars vals)
341 665c255d 2023-08-04 jrmu (cond ((null? vars)
342 665c255d 2023-08-04 jrmu (env-loop (enclosing-environment env)))
343 665c255d 2023-08-04 jrmu ((eq? var (car vars))
344 665c255d 2023-08-04 jrmu (set-car! vals val))
345 665c255d 2023-08-04 jrmu (else (scan (cdr vars) (cdr vals)))))
346 665c255d 2023-08-04 jrmu (if (eq? env the-empty-environment)
347 665c255d 2023-08-04 jrmu (error "Unbound variable -- SET!" var)
348 665c255d 2023-08-04 jrmu (let ((frame (first-frame env)))
349 665c255d 2023-08-04 jrmu (scan (frame-variables frame)
350 665c255d 2023-08-04 jrmu (frame-values frame)))))
351 665c255d 2023-08-04 jrmu (env-loop env))
352 665c255d 2023-08-04 jrmu (define (define-variable! var val env)
353 665c255d 2023-08-04 jrmu (let ((frame (first-frame env)))
354 665c255d 2023-08-04 jrmu (define (scan vars vals)
355 665c255d 2023-08-04 jrmu (cond ((null? vars)
356 665c255d 2023-08-04 jrmu (add-binding-to-frame! var val frame))
357 665c255d 2023-08-04 jrmu ((eq? var (car vars))
358 665c255d 2023-08-04 jrmu (set-car! vals val))
359 665c255d 2023-08-04 jrmu (else (scan (cdr vars) (cdr vals)))))
360 665c255d 2023-08-04 jrmu (scan (frame-variables frame)
361 665c255d 2023-08-04 jrmu (frame-values frame))))
363 665c255d 2023-08-04 jrmu ;; primitives
364 665c255d 2023-08-04 jrmu (define (primitive-procedure? proc)
365 665c255d 2023-08-04 jrmu (tagged-list? proc 'primitive))
366 665c255d 2023-08-04 jrmu (define (primitive-implementation proc) (cadr proc))
367 665c255d 2023-08-04 jrmu (define primitive-procedures
368 665c255d 2023-08-04 jrmu (list (list 'car car)
369 665c255d 2023-08-04 jrmu (list 'cdr cdr)
370 665c255d 2023-08-04 jrmu (list 'caar caar)
371 665c255d 2023-08-04 jrmu (list 'cadr cadr)
372 665c255d 2023-08-04 jrmu (list 'cddr cddr)
373 665c255d 2023-08-04 jrmu (list 'cons cons)
374 665c255d 2023-08-04 jrmu (list 'null? null?)
375 665c255d 2023-08-04 jrmu (list '* *)
376 665c255d 2023-08-04 jrmu (list '/ /)
377 665c255d 2023-08-04 jrmu (list '+ +)
378 665c255d 2023-08-04 jrmu (list '- -)
379 665c255d 2023-08-04 jrmu (list '= =)
380 665c255d 2023-08-04 jrmu (list '< <)
381 665c255d 2023-08-04 jrmu (list '> >)
382 665c255d 2023-08-04 jrmu (list '<= <=)
383 665c255d 2023-08-04 jrmu (list '>= >=)
384 665c255d 2023-08-04 jrmu (list 'remainder remainder)
385 665c255d 2023-08-04 jrmu (list 'eq? eq?)
386 665c255d 2023-08-04 jrmu (list 'equal? equal?)
387 665c255d 2023-08-04 jrmu (list 'display display)))
388 665c255d 2023-08-04 jrmu (define (primitive-procedure-names)
390 665c255d 2023-08-04 jrmu primitive-procedures))
391 665c255d 2023-08-04 jrmu (define (primitive-procedure-objects)
392 665c255d 2023-08-04 jrmu (map (lambda (proc) (list 'primitive (cadr proc)))
393 665c255d 2023-08-04 jrmu primitive-procedures))
394 665c255d 2023-08-04 jrmu (define (apply-primitive-procedure proc args)
395 665c255d 2023-08-04 jrmu (apply-in-underlying-scheme
396 665c255d 2023-08-04 jrmu (primitive-implementation proc) args))
398 665c255d 2023-08-04 jrmu ;; driver-loop
399 665c255d 2023-08-04 jrmu (define input-prompt ";;; M-Eval input:")
400 665c255d 2023-08-04 jrmu (define output-prompt ";;; M-Eval value:")
401 665c255d 2023-08-04 jrmu (define (driver-loop)
402 665c255d 2023-08-04 jrmu (prompt-for-input input-prompt)
403 665c255d 2023-08-04 jrmu (let ((input (read)))
404 665c255d 2023-08-04 jrmu (let ((output (eval input the-global-environment)))
405 665c255d 2023-08-04 jrmu (announce-output output-prompt)
406 665c255d 2023-08-04 jrmu (user-print output)))
407 665c255d 2023-08-04 jrmu (driver-loop))
408 665c255d 2023-08-04 jrmu (define (prompt-for-input string)
409 665c255d 2023-08-04 jrmu (newline) (newline) (display string) (newline))
411 665c255d 2023-08-04 jrmu (define (announce-output string)
412 665c255d 2023-08-04 jrmu (newline) (display string) (newline))
413 665c255d 2023-08-04 jrmu (define (user-print object)
414 665c255d 2023-08-04 jrmu (if (compound-procedure? object)
415 665c255d 2023-08-04 jrmu (display (list 'compound-procedure
416 665c255d 2023-08-04 jrmu (procedure-parameters object)
417 665c255d 2023-08-04 jrmu (procedure-body object)
418 665c255d 2023-08-04 jrmu '<procedure-env>))
419 665c255d 2023-08-04 jrmu (display object)))
420 665c255d 2023-08-04 jrmu (define (setup-environment)
421 665c255d 2023-08-04 jrmu (let ((initial-env
422 665c255d 2023-08-04 jrmu (extend-environment (primitive-procedure-names)
423 665c255d 2023-08-04 jrmu (primitive-procedure-objects)
424 665c255d 2023-08-04 jrmu the-empty-environment)))
425 665c255d 2023-08-04 jrmu (define-variable! 'true true initial-env)
426 665c255d 2023-08-04 jrmu (define-variable! 'false false initial-env)
427 665c255d 2023-08-04 jrmu initial-env))
428 665c255d 2023-08-04 jrmu (define the-global-environment (setup-environment))
430 665c255d 2023-08-04 jrmu ;; auxiliary
431 665c255d 2023-08-04 jrmu (define (test-case actual expected)
433 665c255d 2023-08-04 jrmu (display "Actual: ")
434 665c255d 2023-08-04 jrmu (display actual)
436 665c255d 2023-08-04 jrmu (display "Expected: ")
437 665c255d 2023-08-04 jrmu (display expected)
439 665c255d 2023-08-04 jrmu (define (geval exp) ;; eval globally
440 665c255d 2023-08-04 jrmu (eval exp the-global-environment))
441 665c255d 2023-08-04 jrmu (define (test-eval exp expected)
442 665c255d 2023-08-04 jrmu (test-case (geval exp) expected))
447 665c255d 2023-08-04 jrmu ;; test-suite
449 665c255d 2023-08-04 jrmu ;; procedure definitions
452 665c255d 2023-08-04 jrmu '(define (assoc key records)
453 665c255d 2023-08-04 jrmu (cond ((null? records) false)
454 665c255d 2023-08-04 jrmu ((equal? key (caar records)) (car records))
455 665c255d 2023-08-04 jrmu (else (assoc key (cdr records))))))
458 665c255d 2023-08-04 jrmu '(define (map proc list)
459 665c255d 2023-08-04 jrmu (if (null? list)
461 665c255d 2023-08-04 jrmu (cons (proc (car list))
462 665c255d 2023-08-04 jrmu (map proc (cdr list))))))
465 665c255d 2023-08-04 jrmu '(define (accumulate op initial sequence)
466 665c255d 2023-08-04 jrmu (if (null? sequence)
468 665c255d 2023-08-04 jrmu (op (car sequence)
469 665c255d 2023-08-04 jrmu (accumulate op initial (cdr sequence))))))
471 665c255d 2023-08-04 jrmu ;; all special forms
472 665c255d 2023-08-04 jrmu (test-eval '(begin 5 6) 6)
473 665c255d 2023-08-04 jrmu (test-eval '10 10)
474 665c255d 2023-08-04 jrmu (geval '(define x 3))
475 665c255d 2023-08-04 jrmu (test-eval 'x 3)
476 665c255d 2023-08-04 jrmu (test-eval '(set! x -25) 'ok)
477 665c255d 2023-08-04 jrmu (test-eval 'x -25)
478 665c255d 2023-08-04 jrmu (geval '(define z (lambda (x y) (+ x (* x y)))))
479 665c255d 2023-08-04 jrmu (test-eval '(z 3 4) 15)
480 665c255d 2023-08-04 jrmu (test-eval '(cond ((= x -2) 'x=-2)
481 665c255d 2023-08-04 jrmu ((= x -25) 'x=-25)
482 665c255d 2023-08-04 jrmu (else 'failed))
484 665c255d 2023-08-04 jrmu (test-eval '(if true false true) false)
486 665c255d 2023-08-04 jrmu '(let ((x 4) (y 7))
487 665c255d 2023-08-04 jrmu (+ x y (* x y)))
488 665c255d 2023-08-04 jrmu (+ 4 7 (* 4 7)))
492 665c255d 2023-08-04 jrmu (geval '(define x (+ 3 8)))
493 665c255d 2023-08-04 jrmu (test-eval '(and 0 true x) 11)
494 665c255d 2023-08-04 jrmu (test-eval '(and 0 true x false) false)
495 665c255d 2023-08-04 jrmu (test-eval '(and 0 true x (set! x -2) false) false)
496 665c255d 2023-08-04 jrmu (test-eval 'x -2)
497 665c255d 2023-08-04 jrmu (test-eval '(and 0 true x false (set! x -5)) false)
498 665c255d 2023-08-04 jrmu (test-eval 'x -2)
499 665c255d 2023-08-04 jrmu (test-eval '(or false (set! x 25)) 'ok)
500 665c255d 2023-08-04 jrmu (test-eval 'x 25)
501 665c255d 2023-08-04 jrmu (test-eval '(or (set! x 2) (set! x 4)) 'ok)
502 665c255d 2023-08-04 jrmu (test-eval 'x 2)
503 665c255d 2023-08-04 jrmu (test-eval '(or false (set! x 25) true false) 'ok)
504 665c255d 2023-08-04 jrmu (test-eval 'x 25)
505 665c255d 2023-08-04 jrmu (test-eval '(or ((lambda (x) x) 5)) 5)
506 665c255d 2023-08-04 jrmu (test-eval '(or (begin (set! x (+ x 1)) x)) 26)
512 665c255d 2023-08-04 jrmu '(cond ((assoc 'b '((a 1) (b 2))) => cadr)
513 665c255d 2023-08-04 jrmu (else false))
517 665c255d 2023-08-04 jrmu '(cond ((= 3 4) 'not-true)
518 665c255d 2023-08-04 jrmu ((= (* 2 4) 3) 'also-false)
519 665c255d 2023-08-04 jrmu ((map (lambda (x)
520 665c255d 2023-08-04 jrmu (* x (+ x 1)))
521 665c255d 2023-08-04 jrmu '(2 4 1 9))
523 665c255d 2023-08-04 jrmu (lambda (x)
524 665c255d 2023-08-04 jrmu (accumulate + 0 x)))
525 665c255d 2023-08-04 jrmu (else 'never-reach))
527 665c255d 2023-08-04 jrmu ;; '(6 20 2 90)
530 665c255d 2023-08-04 jrmu ;; procedure definition and application
532 665c255d 2023-08-04 jrmu '(define (factorial n)
533 665c255d 2023-08-04 jrmu (if (= n 0)
535 665c255d 2023-08-04 jrmu (* n (factorial (- n 1))))))
536 665c255d 2023-08-04 jrmu (test-eval '(factorial 5) 120)
541 665c255d 2023-08-04 jrmu '(map (lambda (x)
542 665c255d 2023-08-04 jrmu (* x (+ x 1)))
543 665c255d 2023-08-04 jrmu '(2 1 4 2 8 3))
544 665c255d 2023-08-04 jrmu '(6 2 20 6 72 12))
545 665c255d 2023-08-04 jrmu ;; accumulate
548 665c255d 2023-08-04 jrmu '(accumulate + 0 '(1 2 3 4 5))
551 665c255d 2023-08-04 jrmu ;; make-let
553 665c255d 2023-08-04 jrmu (make-let '(x y) '(3 5) '((+ x y)))
560 665c255d 2023-08-04 jrmu '(let ((x 3))
564 665c255d 2023-08-04 jrmu '(let ((x 3)
569 665c255d 2023-08-04 jrmu '(let ((x 3)
571 665c255d 2023-08-04 jrmu (+ (let ((x (+ y 2))
575 665c255d 2023-08-04 jrmu (+ (* 4 3) 3 2))
577 665c255d 2023-08-04 jrmu '(let ((x 6)
578 665c255d 2023-08-04 jrmu (y (let ((x 2))
580 665c255d 2023-08-04 jrmu (z (let ((a (* 3 2)))
589 665c255d 2023-08-04 jrmu '(let* ((x 3)
590 665c255d 2023-08-04 jrmu (y (+ x 2))
591 665c255d 2023-08-04 jrmu (z (+ x y 5)))
600 665c255d 2023-08-04 jrmu '(let* ((x 3))
601 665c255d 2023-08-04 jrmu (let* ((y 5))
606 665c255d 2023-08-04 jrmu '(let* ((x 3)
607 665c255d 2023-08-04 jrmu (y (+ x 1)))
608 665c255d 2023-08-04 jrmu (+ (let* ((x (+ y 2))
612 665c255d 2023-08-04 jrmu (+ (* 6 6) 3 4))
614 665c255d 2023-08-04 jrmu '(let* ((x 6)
615 665c255d 2023-08-04 jrmu (y (let* ((x 2)
616 665c255d 2023-08-04 jrmu (a (let* ((x (* 3 x)))
619 665c255d 2023-08-04 jrmu (z (+ x y)))
623 665c255d 2023-08-04 jrmu ;; named-let
626 665c255d 2023-08-04 jrmu '(let eight ()
632 665c255d 2023-08-04 jrmu '(let loop ((count 0))
633 665c255d 2023-08-04 jrmu (if (= 100 count)
635 665c255d 2023-08-04 jrmu (loop (+ count 1))))
638 665c255d 2023-08-04 jrmu '(define (prime? x)
639 665c255d 2023-08-04 jrmu (let prime-iter ((i 2))
640 665c255d 2023-08-04 jrmu (cond ((> (* i i) x) true)
641 665c255d 2023-08-04 jrmu ((= (remainder x i) 0) false)
642 665c255d 2023-08-04 jrmu (else (prime-iter (+ i 1)))))))
644 665c255d 2023-08-04 jrmu '(let primes ((x 2)
646 665c255d 2023-08-04 jrmu (cond ((= n 0) '())
647 665c255d 2023-08-04 jrmu ((prime? x)
649 665c255d 2023-08-04 jrmu (primes (+ x 1) (- n 1))))
650 665c255d 2023-08-04 jrmu (else (primes (+ x 1) n))))
651 665c255d 2023-08-04 jrmu '(2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71))
654 665c255d 2023-08-04 jrmu '(define (fib n)
655 665c255d 2023-08-04 jrmu (let fib-iter ((a 1)
658 665c255d 2023-08-04 jrmu (if (= count 0)
660 665c255d 2023-08-04 jrmu (fib-iter (+ a b) a (- count 1))))))
661 665c255d 2023-08-04 jrmu (test-eval '(fib 19) 4181)
665 665c255d 2023-08-04 jrmu '(let ((y 0))
666 665c255d 2023-08-04 jrmu (do ((x 0 (+ x 1)))
667 665c255d 2023-08-04 jrmu ((= x 5) y)
668 665c255d 2023-08-04 jrmu (set! y (+ y 1))))
679 665c255d 2023-08-04 jrmu '(let ((y 0))
681 665c255d 2023-08-04 jrmu ((= y 5) y)
682 665c255d 2023-08-04 jrmu (set! y (+ y 1))))
686 665c255d 2023-08-04 jrmu '(do ((y '(1 2 3 4)))
687 665c255d 2023-08-04 jrmu ((null? y))
688 665c255d 2023-08-04 jrmu (set! y (cdr y)))
691 665c255d 2023-08-04 jrmu '(let ((y 0))
692 665c255d 2023-08-04 jrmu (do ((x 0 (+ x 1)))
693 665c255d 2023-08-04 jrmu ((= x 5) y)
694 665c255d 2023-08-04 jrmu (set! y (+ y 1))))
697 665c255d 2023-08-04 jrmu '(let ((x '(1 3 5 7 9)))
698 665c255d 2023-08-04 jrmu (do ((x x (cdr x))
699 665c255d 2023-08-04 jrmu (sum 0 (+ sum (car x))))
700 665c255d 2023-08-04 jrmu ((null? x) sum)))
703 665c255d 2023-08-04 jrmu '(let ((z '()))
704 665c255d 2023-08-04 jrmu (do ((x '(1 2 3 4) (cdr x))
705 665c255d 2023-08-04 jrmu (y '(1 2 3 4 5 6 7 8) (cddr y)))
706 665c255d 2023-08-04 jrmu ((null? x) y x z)
707 665c255d 2023-08-04 jrmu (set! z (cons (car x) z))))
708 665c255d 2023-08-04 jrmu '(4 3 2 1))