1 665c255d 2023-08-04 jrmu (define (ambeval exp env succeed fail)
2 665c255d 2023-08-04 jrmu ((analyze exp) env succeed fail))
3 665c255d 2023-08-04 jrmu (define (analyze exp)
4 665c255d 2023-08-04 jrmu (cond ((self-evaluating? exp)
5 665c255d 2023-08-04 jrmu (analyze-self-evaluating exp))
6 665c255d 2023-08-04 jrmu ((quoted? exp) (analyze-quoted exp))
7 665c255d 2023-08-04 jrmu ((variable? exp) (analyze-variable exp))
8 665c255d 2023-08-04 jrmu ((assignment? exp) (analyze-assignment exp))
9 665c255d 2023-08-04 jrmu ((definition? exp) (analyze-definition exp))
10 665c255d 2023-08-04 jrmu ((if? exp) (analyze-if exp))
11 665c255d 2023-08-04 jrmu ((and? exp) (analyze (and->if exp)))
12 665c255d 2023-08-04 jrmu ((or? exp) (analyze (or->if exp)))
13 665c255d 2023-08-04 jrmu ((lambda? exp) (analyze-lambda exp))
14 665c255d 2023-08-04 jrmu ((let? exp) (analyze (let->combination exp)))
15 665c255d 2023-08-04 jrmu ((let*? exp) (analyze (let*->nested-lets exp)))
16 665c255d 2023-08-04 jrmu ((named-let? exp) (analyze (named-let->combination exp)))
17 665c255d 2023-08-04 jrmu ((letrec? exp) (analyze (letrec->let exp)))
18 665c255d 2023-08-04 jrmu ((do? exp) (analyze (do->combination exp)))
19 665c255d 2023-08-04 jrmu ((begin? exp) (analyze-sequence (begin-actions exp)))
20 665c255d 2023-08-04 jrmu ((cond? exp) (analyze (cond->if exp)))
21 665c255d 2023-08-04 jrmu ((amb? exp) (analyze-amb exp))
22 665c255d 2023-08-04 jrmu ((ramb? exp) (analyze-ramb exp))
23 665c255d 2023-08-04 jrmu ((application? exp) (analyze-application exp))
25 665c255d 2023-08-04 jrmu (error "Unknown expression type -- ANALYZE" exp))))
28 665c255d 2023-08-04 jrmu ;; analyzing procedures
29 665c255d 2023-08-04 jrmu (define (analyze-self-evaluating exp)
30 665c255d 2023-08-04 jrmu (lambda (env succeed fail)
31 665c255d 2023-08-04 jrmu (succeed exp fail)))
32 665c255d 2023-08-04 jrmu (define (analyze-quoted exp)
33 665c255d 2023-08-04 jrmu (let ((qval (text-of-quotation exp)))
34 665c255d 2023-08-04 jrmu (lambda (env succeed fail)
35 665c255d 2023-08-04 jrmu (succeed qval fail))))
36 665c255d 2023-08-04 jrmu (define (analyze-variable exp)
37 665c255d 2023-08-04 jrmu (lambda (env succeed fail)
38 665c255d 2023-08-04 jrmu (succeed (lookup-variable-value exp env)
40 665c255d 2023-08-04 jrmu (define (analyze-lambda exp)
41 665c255d 2023-08-04 jrmu (let ((vars (lambda-parameters exp))
42 665c255d 2023-08-04 jrmu ;; (bproc (analyze-sequence (scan-out-defines (lambda-body exp)))))
43 665c255d 2023-08-04 jrmu (bproc (analyze-sequence (lambda-body exp))))
44 665c255d 2023-08-04 jrmu (lambda (env succeed fail)
45 665c255d 2023-08-04 jrmu (succeed (make-procedure vars bproc env)
47 665c255d 2023-08-04 jrmu (define (analyze-if exp)
48 665c255d 2023-08-04 jrmu (let ((pproc (analyze (if-predicate exp)))
49 665c255d 2023-08-04 jrmu (cproc (analyze (if-consequent exp)))
50 665c255d 2023-08-04 jrmu (aproc (analyze (if-alternative exp))))
51 665c255d 2023-08-04 jrmu (lambda (env succeed fail)
53 665c255d 2023-08-04 jrmu ;; success continuation for evaluating the predicate
54 665c255d 2023-08-04 jrmu ;; to obtain pred-value
55 665c255d 2023-08-04 jrmu (lambda (pred-value fail2)
56 665c255d 2023-08-04 jrmu (if (true? pred-value)
57 665c255d 2023-08-04 jrmu (cproc env succeed fail2)
58 665c255d 2023-08-04 jrmu (aproc env succeed fail2)))
59 665c255d 2023-08-04 jrmu ;; failure continuation for evaluating the predicate
61 665c255d 2023-08-04 jrmu (define (analyze-sequence exps)
62 665c255d 2023-08-04 jrmu (define (sequentially a b)
63 665c255d 2023-08-04 jrmu (lambda (env succeed fail)
65 665c255d 2023-08-04 jrmu ;; success continuation for calling a
66 665c255d 2023-08-04 jrmu (lambda (a-value fail2)
67 665c255d 2023-08-04 jrmu (b env succeed fail2))
68 665c255d 2023-08-04 jrmu ;; failure continuation for calling a
70 665c255d 2023-08-04 jrmu (define (loop first-proc rest-procs)
71 665c255d 2023-08-04 jrmu (if (null? rest-procs)
73 665c255d 2023-08-04 jrmu (loop (sequentially first-proc (car rest-procs))
74 665c255d 2023-08-04 jrmu (cdr rest-procs))))
75 665c255d 2023-08-04 jrmu (let ((procs (map analyze exps)))
76 665c255d 2023-08-04 jrmu (if (null? procs)
77 665c255d 2023-08-04 jrmu (error "Empty sequence -- ANALYZE"))
78 665c255d 2023-08-04 jrmu (loop (car procs) (cdr procs))))
79 665c255d 2023-08-04 jrmu (define (analyze-definition exp)
80 665c255d 2023-08-04 jrmu (let ((var (definition-variable exp))
81 665c255d 2023-08-04 jrmu (vproc (analyze (definition-value exp))))
82 665c255d 2023-08-04 jrmu (lambda (env succeed fail)
84 665c255d 2023-08-04 jrmu (lambda (val fail2)
85 665c255d 2023-08-04 jrmu (define-variable! var val env)
86 665c255d 2023-08-04 jrmu (succeed 'ok fail2))
88 665c255d 2023-08-04 jrmu (define (analyze-assignment exp)
89 665c255d 2023-08-04 jrmu (let ((var (assignment-variable exp))
90 665c255d 2023-08-04 jrmu (vproc (analyze (assignment-value exp))))
91 665c255d 2023-08-04 jrmu (lambda (env succeed fail)
93 665c255d 2023-08-04 jrmu (lambda (val fail2) ; *1*
94 665c255d 2023-08-04 jrmu (let ((old-value
95 665c255d 2023-08-04 jrmu (lookup-variable-value var env)))
96 665c255d 2023-08-04 jrmu (set-variable-value! var val env)
97 665c255d 2023-08-04 jrmu (succeed 'ok
98 665c255d 2023-08-04 jrmu (lambda () ; *2*
99 665c255d 2023-08-04 jrmu (set-variable-value! var
102 665c255d 2023-08-04 jrmu (fail2)))))
105 665c255d 2023-08-04 jrmu (define (analyze-application exp)
106 665c255d 2023-08-04 jrmu (let ((fproc (analyze (operator exp)))
107 665c255d 2023-08-04 jrmu (aprocs (map analyze (operands exp))))
108 665c255d 2023-08-04 jrmu (lambda (env succeed fail)
110 665c255d 2023-08-04 jrmu (lambda (proc fail2)
111 665c255d 2023-08-04 jrmu (get-args aprocs
113 665c255d 2023-08-04 jrmu (lambda (args fail3)
114 665c255d 2023-08-04 jrmu (execute-application
115 665c255d 2023-08-04 jrmu proc args succeed fail3))
118 665c255d 2023-08-04 jrmu (define (get-args aprocs env succeed fail)
119 665c255d 2023-08-04 jrmu (if (null? aprocs)
120 665c255d 2023-08-04 jrmu (succeed '() fail)
121 665c255d 2023-08-04 jrmu ((car aprocs) env
122 665c255d 2023-08-04 jrmu ;; success continuation for this aproc
123 665c255d 2023-08-04 jrmu (lambda (arg fail2)
124 665c255d 2023-08-04 jrmu (get-args (cdr aprocs)
126 665c255d 2023-08-04 jrmu ;; success continuation for recursive
127 665c255d 2023-08-04 jrmu ;; call to get-args
128 665c255d 2023-08-04 jrmu (lambda (args fail3)
129 665c255d 2023-08-04 jrmu (succeed (cons arg args)
134 665c255d 2023-08-04 jrmu (define (analyze-amb exp)
135 665c255d 2023-08-04 jrmu (let ((cprocs (map analyze (amb-choices exp))))
136 665c255d 2023-08-04 jrmu (lambda (env succeed fail)
137 665c255d 2023-08-04 jrmu (define (try-next choices)
138 665c255d 2023-08-04 jrmu (if (null? choices)
140 665c255d 2023-08-04 jrmu ((car choices) env
143 665c255d 2023-08-04 jrmu (try-next (cdr choices))))))
144 665c255d 2023-08-04 jrmu (try-next cprocs))))
151 665c255d 2023-08-04 jrmu (define (tagged-list? exp tag)
152 665c255d 2023-08-04 jrmu (if (pair? exp)
153 665c255d 2023-08-04 jrmu (eq? (car exp) tag)
157 665c255d 2023-08-04 jrmu (define (amb? exp) (tagged-list? exp 'amb))
158 665c255d 2023-08-04 jrmu (define (amb-choices exp) (cdr exp))
160 665c255d 2023-08-04 jrmu ;; self-evaluating/variable/quoted
161 665c255d 2023-08-04 jrmu (define (self-evaluating? exp)
162 665c255d 2023-08-04 jrmu (cond ((number? exp) true)
163 665c255d 2023-08-04 jrmu ((string? exp) true)
164 665c255d 2023-08-04 jrmu (else false)))
165 665c255d 2023-08-04 jrmu (define (variable? exp) (symbol? exp))
166 665c255d 2023-08-04 jrmu (define (quoted? exp)
167 665c255d 2023-08-04 jrmu (tagged-list? exp 'quote))
168 665c255d 2023-08-04 jrmu (define (text-of-quotation exp) (cadr exp))
170 665c255d 2023-08-04 jrmu ;; assignment/definition
171 665c255d 2023-08-04 jrmu (define (assignment? exp)
172 665c255d 2023-08-04 jrmu (tagged-list? exp 'set!))
173 665c255d 2023-08-04 jrmu (define (assignment-variable exp) (cadr exp))
174 665c255d 2023-08-04 jrmu (define (assignment-value exp) (caddr exp))
175 665c255d 2023-08-04 jrmu (define (make-assignment var val)
176 665c255d 2023-08-04 jrmu (list 'set! var val))
177 665c255d 2023-08-04 jrmu (define (definition? exp)
178 665c255d 2023-08-04 jrmu (tagged-list? exp 'define))
179 665c255d 2023-08-04 jrmu (define (definition-variable exp)
180 665c255d 2023-08-04 jrmu (if (symbol? (cadr exp))
182 665c255d 2023-08-04 jrmu (caadr exp)))
183 665c255d 2023-08-04 jrmu (define (definition-value exp)
184 665c255d 2023-08-04 jrmu (if (symbol? (cadr exp))
185 665c255d 2023-08-04 jrmu (caddr exp)
186 665c255d 2023-08-04 jrmu (make-lambda (cdadr exp) ; formal parameters
187 665c255d 2023-08-04 jrmu (cddr exp)))) ; body
188 665c255d 2023-08-04 jrmu (define (make-definition var val)
189 665c255d 2023-08-04 jrmu `(define ,var ,val))
191 665c255d 2023-08-04 jrmu ;; if/and/or
192 665c255d 2023-08-04 jrmu (define (if? exp) (tagged-list? exp 'if))
193 665c255d 2023-08-04 jrmu (define (if-predicate exp) (cadr exp))
194 665c255d 2023-08-04 jrmu (define (if-consequent exp) (caddr exp))
195 665c255d 2023-08-04 jrmu (define (if-alternative exp)
196 665c255d 2023-08-04 jrmu (if (not (null? (cdddr exp)))
197 665c255d 2023-08-04 jrmu (cadddr exp)
199 665c255d 2023-08-04 jrmu (define (make-if predicate consequent alternative)
200 665c255d 2023-08-04 jrmu (list 'if predicate consequent alternative))
202 665c255d 2023-08-04 jrmu (define (and? exp)
203 665c255d 2023-08-04 jrmu (tagged-list? exp 'and))
204 665c255d 2023-08-04 jrmu (define (and-clauses exp)
206 665c255d 2023-08-04 jrmu (define (or? exp)
207 665c255d 2023-08-04 jrmu (tagged-list? exp 'or))
208 665c255d 2023-08-04 jrmu (define (or-clauses exp)
210 665c255d 2023-08-04 jrmu (define (and->if exp)
211 665c255d 2023-08-04 jrmu (define (expand-clauses clauses)
212 665c255d 2023-08-04 jrmu (cond ((null? clauses) 'true)
213 665c255d 2023-08-04 jrmu ((null? (cdr clauses)) (car clauses))
214 665c255d 2023-08-04 jrmu (else (make-if (car clauses)
215 665c255d 2023-08-04 jrmu (expand-clauses (cdr clauses))
217 665c255d 2023-08-04 jrmu (expand-clauses (and-clauses exp)))
218 665c255d 2023-08-04 jrmu (define (or->if exp)
219 665c255d 2023-08-04 jrmu (define (expand-clauses clauses)
220 665c255d 2023-08-04 jrmu (if (null? clauses)
222 665c255d 2023-08-04 jrmu (make-if (car clauses)
223 665c255d 2023-08-04 jrmu (car clauses)
224 665c255d 2023-08-04 jrmu (expand-clauses (cdr clauses)))))
225 665c255d 2023-08-04 jrmu (expand-clauses (or-clauses exp)))
227 665c255d 2023-08-04 jrmu ;; lambda/let/let*/letrec
228 665c255d 2023-08-04 jrmu (define (lambda? exp) (tagged-list? exp 'lambda))
229 665c255d 2023-08-04 jrmu (define (lambda-parameters exp) (cadr exp))
230 665c255d 2023-08-04 jrmu (define (lambda-body exp) (cddr exp))
231 665c255d 2023-08-04 jrmu (define (make-lambda parameters body)
232 665c255d 2023-08-04 jrmu (cons 'lambda (cons parameters body)))
234 665c255d 2023-08-04 jrmu (define (make-let vars vals body)
236 665c255d 2023-08-04 jrmu (cons (map list vars vals)
238 665c255d 2023-08-04 jrmu (define (let? exp)
239 665c255d 2023-08-04 jrmu (and (tagged-list? exp 'let)
240 665c255d 2023-08-04 jrmu (not (symbol? (cadr exp)))))
241 665c255d 2023-08-04 jrmu (define (let-vars exp)
242 665c255d 2023-08-04 jrmu (map car (cadr exp)))
243 665c255d 2023-08-04 jrmu (define (let-vals exp)
244 665c255d 2023-08-04 jrmu (map cadr (cadr exp)))
245 665c255d 2023-08-04 jrmu (define (let-body exp)
246 665c255d 2023-08-04 jrmu (cddr exp))
247 665c255d 2023-08-04 jrmu (define (let->combination exp)
248 665c255d 2023-08-04 jrmu (make-application (make-lambda (let-vars exp) (let-body exp))
249 665c255d 2023-08-04 jrmu (let-vals exp)))
250 665c255d 2023-08-04 jrmu (define (named-let? exp)
251 665c255d 2023-08-04 jrmu (and (tagged-list? exp 'let)
252 665c255d 2023-08-04 jrmu (symbol? (cadr exp))))
253 665c255d 2023-08-04 jrmu (define (named-let-name exp)
254 665c255d 2023-08-04 jrmu (cadr exp))
255 665c255d 2023-08-04 jrmu (define (named-let-vars exp)
256 665c255d 2023-08-04 jrmu (map car (caddr exp)))
257 665c255d 2023-08-04 jrmu (define (named-let-vals exp)
258 665c255d 2023-08-04 jrmu (map cadr (caddr exp)))
259 665c255d 2023-08-04 jrmu (define (named-let-body exp)
260 665c255d 2023-08-04 jrmu (cdddr exp))
261 665c255d 2023-08-04 jrmu (define (named-let->combination exp)
262 665c255d 2023-08-04 jrmu (sequence->exp
263 665c255d 2023-08-04 jrmu (list (make-definition (named-let-name exp)
264 665c255d 2023-08-04 jrmu (make-lambda (named-let-vars exp)
265 665c255d 2023-08-04 jrmu (named-let-body exp)))
266 665c255d 2023-08-04 jrmu (make-application (named-let-name exp)
267 665c255d 2023-08-04 jrmu (named-let-vals exp)))))
268 665c255d 2023-08-04 jrmu (define (make-named-let name vars vals body)
271 665c255d 2023-08-04 jrmu (cons (map list vars vals)
274 665c255d 2023-08-04 jrmu (define (letrec? exp)
275 665c255d 2023-08-04 jrmu (tagged-list? exp 'letrec))
277 665c255d 2023-08-04 jrmu (define (letrec-vars exp)
278 665c255d 2023-08-04 jrmu (map car (cadr exp)))
279 665c255d 2023-08-04 jrmu (define (letrec-vals exp)
280 665c255d 2023-08-04 jrmu (map cadr (cadr exp)))
281 665c255d 2023-08-04 jrmu (define (letrec-body exp)
282 665c255d 2023-08-04 jrmu (cddr exp))
283 665c255d 2023-08-04 jrmu (define (letrec->let exp)
284 665c255d 2023-08-04 jrmu (let* ((vars (letrec-vars exp))
285 665c255d 2023-08-04 jrmu (unassigneds (map (lambda (var) ''*unassigned*)
287 665c255d 2023-08-04 jrmu (vals (letrec-vals exp))
288 665c255d 2023-08-04 jrmu (assignments (map (lambda (var val)
289 665c255d 2023-08-04 jrmu (make-assignment var val))
292 665c255d 2023-08-04 jrmu (body (letrec-body exp)))
293 665c255d 2023-08-04 jrmu (make-let vars
294 665c255d 2023-08-04 jrmu unassigneds
295 665c255d 2023-08-04 jrmu (append assignments body))))
297 665c255d 2023-08-04 jrmu (define (make-application op args)
298 665c255d 2023-08-04 jrmu (cons op args))
300 665c255d 2023-08-04 jrmu (define (let*? exp)
301 665c255d 2023-08-04 jrmu (tagged-list? exp 'let*))
302 665c255d 2023-08-04 jrmu (define let*-vars let-vars)
303 665c255d 2023-08-04 jrmu (define let*-vals let-vals)
304 665c255d 2023-08-04 jrmu (define let*-body let-body)
305 665c255d 2023-08-04 jrmu (define (let*->nested-lets exp)
306 665c255d 2023-08-04 jrmu (define (expand-lets vars vals)
307 665c255d 2023-08-04 jrmu (if (null? (cdr vars))
308 665c255d 2023-08-04 jrmu (make-let (list (car vars))
309 665c255d 2023-08-04 jrmu (list (car vals))
310 665c255d 2023-08-04 jrmu (let*-body exp))
311 665c255d 2023-08-04 jrmu (make-let (list (car vars))
312 665c255d 2023-08-04 jrmu (list (car vals))
313 665c255d 2023-08-04 jrmu (list (expand-lets (cdr vars) (cdr vals))))))
314 665c255d 2023-08-04 jrmu (let ((vars (let*-vars exp))
315 665c255d 2023-08-04 jrmu (vals (let*-vals exp)))
316 665c255d 2023-08-04 jrmu (if (null? vars)
317 665c255d 2023-08-04 jrmu (sequence->exp (let*-body exp))
318 665c255d 2023-08-04 jrmu (expand-lets vars vals))))
321 665c255d 2023-08-04 jrmu (define (do? exp)
322 665c255d 2023-08-04 jrmu (tagged-list? exp 'do))
323 665c255d 2023-08-04 jrmu (define (do-vars exp)
324 665c255d 2023-08-04 jrmu (map car (cadr exp)))
325 665c255d 2023-08-04 jrmu (define (do-inits exp)
326 665c255d 2023-08-04 jrmu (map cadr (cadr exp)))
327 665c255d 2023-08-04 jrmu (define (do-steps exp)
328 665c255d 2023-08-04 jrmu (map (lambda (var-init-step)
329 665c255d 2023-08-04 jrmu (if (null? (cddr var-init-step))
330 665c255d 2023-08-04 jrmu (car var-init-step)
331 665c255d 2023-08-04 jrmu (caddr var-init-step)))
332 665c255d 2023-08-04 jrmu (cadr exp)))
333 665c255d 2023-08-04 jrmu (define (do-test exp)
334 665c255d 2023-08-04 jrmu (caaddr exp))
335 665c255d 2023-08-04 jrmu (define (do-expressions exp)
336 665c255d 2023-08-04 jrmu (if (null? (cdaddr exp))
337 665c255d 2023-08-04 jrmu (caddr exp)
338 665c255d 2023-08-04 jrmu (cdaddr exp)))
339 665c255d 2023-08-04 jrmu (define (do-commands exp)
340 665c255d 2023-08-04 jrmu (cdddr exp))
341 665c255d 2023-08-04 jrmu (define (do->combination exp)
342 665c255d 2023-08-04 jrmu (make-named-let
344 665c255d 2023-08-04 jrmu (do-vars exp)
345 665c255d 2023-08-04 jrmu (do-inits exp)
348 665c255d 2023-08-04 jrmu (do-test exp)
349 665c255d 2023-08-04 jrmu (sequence->exp (do-expressions exp))
350 665c255d 2023-08-04 jrmu (sequence->exp
351 665c255d 2023-08-04 jrmu (append (do-commands exp)
352 665c255d 2023-08-04 jrmu (list (make-application
354 665c255d 2023-08-04 jrmu (do-steps exp)))))))))
357 665c255d 2023-08-04 jrmu ;; begin/sequence
358 665c255d 2023-08-04 jrmu (define (begin? exp) (tagged-list? exp 'begin))
359 665c255d 2023-08-04 jrmu (define (begin-actions exp) (cdr exp))
360 665c255d 2023-08-04 jrmu (define (last-exp? seq) (null? (cdr seq)))
361 665c255d 2023-08-04 jrmu (define (first-exp seq) (car seq))
362 665c255d 2023-08-04 jrmu (define (rest-exps seq) (cdr seq))
363 665c255d 2023-08-04 jrmu (define (sequence->exp seq)
364 665c255d 2023-08-04 jrmu (cond ((null? seq) seq)
365 665c255d 2023-08-04 jrmu ((last-exp? seq) (first-exp seq))
366 665c255d 2023-08-04 jrmu (else (make-begin seq))))
367 665c255d 2023-08-04 jrmu (define (make-begin seq) (cons 'begin seq))
369 665c255d 2023-08-04 jrmu ;; application
370 665c255d 2023-08-04 jrmu (define (application? exp) (pair? exp))
371 665c255d 2023-08-04 jrmu (define (operator exp) (car exp))
372 665c255d 2023-08-04 jrmu (define (operands exp) (cdr exp))
373 665c255d 2023-08-04 jrmu (define (no-operands? ops) (null? ops))
374 665c255d 2023-08-04 jrmu (define (first-operand ops) (car ops))
375 665c255d 2023-08-04 jrmu (define (rest-operands ops) (cdr ops))
378 665c255d 2023-08-04 jrmu (define (cond? exp) (tagged-list? exp 'cond))
379 665c255d 2023-08-04 jrmu (define (cond-clauses exp) (cdr exp))
380 665c255d 2023-08-04 jrmu (define (cond-else-clause? clause)
381 665c255d 2023-08-04 jrmu (eq? (cond-predicate clause) 'else))
382 665c255d 2023-08-04 jrmu (define (cond-predicate clause) (car clause))
383 665c255d 2023-08-04 jrmu (define (cond-actions clause) (cdr clause))
384 665c255d 2023-08-04 jrmu (define (cond-extended-clause? clause)
385 665c255d 2023-08-04 jrmu (and (not (null? (cdr clause))) (eq? (cadr clause) '=>)))
386 665c255d 2023-08-04 jrmu (define (cond-extended-proc clause)
387 665c255d 2023-08-04 jrmu (caddr clause))
388 665c255d 2023-08-04 jrmu (define (cond->if exp)
389 665c255d 2023-08-04 jrmu (expand-clauses (cond-clauses exp)))
390 665c255d 2023-08-04 jrmu (define (expand-clauses clauses)
391 665c255d 2023-08-04 jrmu (if (null? clauses)
392 665c255d 2023-08-04 jrmu 'false ; no else clause
393 665c255d 2023-08-04 jrmu (let ((first (car clauses))
394 665c255d 2023-08-04 jrmu (rest (cdr clauses)))
395 665c255d 2023-08-04 jrmu (if (cond-else-clause? first)
396 665c255d 2023-08-04 jrmu (if (null? rest)
397 665c255d 2023-08-04 jrmu (sequence->exp (cond-actions first))
398 665c255d 2023-08-04 jrmu (error "ELSE clause isn't last -- COND->IF"
400 665c255d 2023-08-04 jrmu (if (cond-extended-clause? first)
401 665c255d 2023-08-04 jrmu (make-if (cond-predicate first)
402 665c255d 2023-08-04 jrmu (make-application
403 665c255d 2023-08-04 jrmu (cond-extended-proc first)
404 665c255d 2023-08-04 jrmu (list (cond-predicate first)))
405 665c255d 2023-08-04 jrmu (expand-clauses rest))
406 665c255d 2023-08-04 jrmu (make-if (cond-predicate first)
407 665c255d 2023-08-04 jrmu (sequence->exp (cond-actions first))
408 665c255d 2023-08-04 jrmu (expand-clauses rest)))))))
409 665c255d 2023-08-04 jrmu (define (true? x)
410 665c255d 2023-08-04 jrmu (not (eq? x false)))
411 665c255d 2023-08-04 jrmu (define (false? x)
412 665c255d 2023-08-04 jrmu (eq? x false))
414 665c255d 2023-08-04 jrmu ;; procedure
415 665c255d 2023-08-04 jrmu (define (make-procedure parameters body env)
416 665c255d 2023-08-04 jrmu (list 'procedure parameters body env))
417 665c255d 2023-08-04 jrmu (define (scan-out-defines body)
418 665c255d 2023-08-04 jrmu (let* ((definitions (filter definition? body))
419 665c255d 2023-08-04 jrmu (vars (map definition-variable definitions))
420 665c255d 2023-08-04 jrmu (unassigneds (map (lambda (var) ''*unassigned*)
422 665c255d 2023-08-04 jrmu (vals (map definition-value definitions))
423 665c255d 2023-08-04 jrmu (assignments
424 665c255d 2023-08-04 jrmu (map (lambda (var val)
425 665c255d 2023-08-04 jrmu (make-assignment var val))
426 665c255d 2023-08-04 jrmu vars vals))
427 665c255d 2023-08-04 jrmu (exps (remove definition? body)))
428 665c255d 2023-08-04 jrmu (if (null? definitions)
431 665c255d 2023-08-04 jrmu (make-let vars
432 665c255d 2023-08-04 jrmu unassigneds
433 665c255d 2023-08-04 jrmu (append assignments exps))))))
434 665c255d 2023-08-04 jrmu (define (compound-procedure? p)
435 665c255d 2023-08-04 jrmu (tagged-list? p 'procedure))
436 665c255d 2023-08-04 jrmu (define (procedure-parameters p) (cadr p))
437 665c255d 2023-08-04 jrmu (define (procedure-body p) (caddr p))
438 665c255d 2023-08-04 jrmu (define (procedure-environment p) (cadddr p))
440 665c255d 2023-08-04 jrmu ;; environment
441 665c255d 2023-08-04 jrmu (define (enclosing-environment env) (cdr env))
442 665c255d 2023-08-04 jrmu (define (first-frame env) (car env))
443 665c255d 2023-08-04 jrmu (define the-empty-environment '())
444 665c255d 2023-08-04 jrmu (define (make-frame variables values)
445 665c255d 2023-08-04 jrmu (cons variables values))
446 665c255d 2023-08-04 jrmu (define (frame-variables frame) (car frame))
447 665c255d 2023-08-04 jrmu (define (frame-values frame) (cdr frame))
448 665c255d 2023-08-04 jrmu (define (add-binding-to-frame! var val frame)
449 665c255d 2023-08-04 jrmu (set-car! frame (cons var (car frame)))
450 665c255d 2023-08-04 jrmu (set-cdr! frame (cons val (cdr frame))))
451 665c255d 2023-08-04 jrmu (define (extend-environment vars vals base-env)
452 665c255d 2023-08-04 jrmu (if (= (length vars) (length vals))
453 665c255d 2023-08-04 jrmu (cons (make-frame vars vals) base-env)
454 665c255d 2023-08-04 jrmu (if (< (length vars) (length vals))
455 665c255d 2023-08-04 jrmu (error "Too many arguments supplied" vars vals)
456 665c255d 2023-08-04 jrmu (error "Too few arguments supplied" vars vals))))
457 665c255d 2023-08-04 jrmu (define (lookup-variable-value var env)
458 665c255d 2023-08-04 jrmu (define (env-loop env)
459 665c255d 2023-08-04 jrmu (define (scan vars vals)
460 665c255d 2023-08-04 jrmu (cond ((null? vars)
461 665c255d 2023-08-04 jrmu (env-loop (enclosing-environment env)))
462 665c255d 2023-08-04 jrmu ((eq? var (car vars))
463 665c255d 2023-08-04 jrmu (let ((val (car vals)))
464 665c255d 2023-08-04 jrmu (if (eq? val '*unassigned*)
465 665c255d 2023-08-04 jrmu (error "Var not yet defined -- LOOKUP-VARIABLE-VALUE" var)
467 665c255d 2023-08-04 jrmu (else (scan (cdr vars) (cdr vals)))))
468 665c255d 2023-08-04 jrmu (if (eq? env the-empty-environment)
469 665c255d 2023-08-04 jrmu (error "Unbound variable" var)
470 665c255d 2023-08-04 jrmu (let ((frame (first-frame env)))
471 665c255d 2023-08-04 jrmu (scan (frame-variables frame)
472 665c255d 2023-08-04 jrmu (frame-values frame)))))
473 665c255d 2023-08-04 jrmu (env-loop env))
474 665c255d 2023-08-04 jrmu (define (set-variable-value! var val env)
475 665c255d 2023-08-04 jrmu (define (env-loop env)
476 665c255d 2023-08-04 jrmu (define (scan vars vals)
477 665c255d 2023-08-04 jrmu (cond ((null? vars)
478 665c255d 2023-08-04 jrmu (env-loop (enclosing-environment env)))
479 665c255d 2023-08-04 jrmu ((eq? var (car vars))
480 665c255d 2023-08-04 jrmu (set-car! vals val))
481 665c255d 2023-08-04 jrmu (else (scan (cdr vars) (cdr vals)))))
482 665c255d 2023-08-04 jrmu (if (eq? env the-empty-environment)
483 665c255d 2023-08-04 jrmu (error "Unbound variable -- SET!" var)
484 665c255d 2023-08-04 jrmu (let ((frame (first-frame env)))
485 665c255d 2023-08-04 jrmu (scan (frame-variables frame)
486 665c255d 2023-08-04 jrmu (frame-values frame)))))
487 665c255d 2023-08-04 jrmu (env-loop env))
488 665c255d 2023-08-04 jrmu (define (define-variable! var val env)
489 665c255d 2023-08-04 jrmu (let ((frame (first-frame env)))
490 665c255d 2023-08-04 jrmu (define (scan vars vals)
491 665c255d 2023-08-04 jrmu (cond ((null? vars)
492 665c255d 2023-08-04 jrmu (add-binding-to-frame! var val frame))
493 665c255d 2023-08-04 jrmu ((eq? var (car vars))
494 665c255d 2023-08-04 jrmu (set-car! vals val))
495 665c255d 2023-08-04 jrmu (else (scan (cdr vars) (cdr vals)))))
496 665c255d 2023-08-04 jrmu (scan (frame-variables frame)
497 665c255d 2023-08-04 jrmu (frame-values frame))))
499 665c255d 2023-08-04 jrmu ;; (define (remove-binding-from-frame! var frame)
500 665c255d 2023-08-04 jrmu ;; (define (scan vars vals)
501 665c255d 2023-08-04 jrmu ;; (cond ((null? (cdr vars))
502 665c255d 2023-08-04 jrmu ;; (error "Binding not found -- REMOVE-BINDING-FROM-FRAME!" var))
503 665c255d 2023-08-04 jrmu ;; ((eq? var (cadr vars))
504 665c255d 2023-08-04 jrmu ;; (set-cdr! vars (cddr vars))
505 665c255d 2023-08-04 jrmu ;; (set-cdr! vals (cddr vals)))
506 665c255d 2023-08-04 jrmu ;; (else (scan (cdr vars) (cdr vals)))))
507 665c255d 2023-08-04 jrmu ;; (let ((vars (frame-variables frame))
508 665c255d 2023-08-04 jrmu ;; (vals (frame-values frame)))
509 665c255d 2023-08-04 jrmu ;; (if (eq? var (car vars))
510 665c255d 2023-08-04 jrmu ;; (begin (set-car! frame (cdr vars))
511 665c255d 2023-08-04 jrmu ;; (set-cdr! frame (cdr vals)))
512 665c255d 2023-08-04 jrmu ;; (scan vars vals))))
514 665c255d 2023-08-04 jrmu ;; primitives
515 665c255d 2023-08-04 jrmu (define (primitive-procedure? proc)
516 665c255d 2023-08-04 jrmu (tagged-list? proc 'primitive))
517 665c255d 2023-08-04 jrmu (define (primitive-implementation proc) (cadr proc))
518 665c255d 2023-08-04 jrmu (define primitive-procedures
519 665c255d 2023-08-04 jrmu (list (list 'car car)
520 665c255d 2023-08-04 jrmu (list 'cdr cdr)
521 665c255d 2023-08-04 jrmu (list 'caar caar)
522 665c255d 2023-08-04 jrmu (list 'cadr cadr)
523 665c255d 2023-08-04 jrmu (list 'cddr cddr)
524 665c255d 2023-08-04 jrmu (list 'cons cons)
525 665c255d 2023-08-04 jrmu (list 'null? null?)
526 665c255d 2023-08-04 jrmu (list '* *)
527 665c255d 2023-08-04 jrmu (list '/ /)
528 665c255d 2023-08-04 jrmu (list '+ +)
529 665c255d 2023-08-04 jrmu (list '- -)
530 665c255d 2023-08-04 jrmu (list '= =)
531 665c255d 2023-08-04 jrmu (list '< <)
532 665c255d 2023-08-04 jrmu (list '> >)
533 665c255d 2023-08-04 jrmu (list '<= <=)
534 665c255d 2023-08-04 jrmu (list '>= >=)
535 665c255d 2023-08-04 jrmu (list 'remainder remainder)
536 665c255d 2023-08-04 jrmu (list 'eq? eq?)
537 665c255d 2023-08-04 jrmu (list 'equal? equal?)
538 665c255d 2023-08-04 jrmu (list 'display display)))
539 665c255d 2023-08-04 jrmu (define (primitive-procedure-names)
541 665c255d 2023-08-04 jrmu primitive-procedures))
542 665c255d 2023-08-04 jrmu (define (primitive-procedure-objects)
543 665c255d 2023-08-04 jrmu (map (lambda (proc) (list 'primitive (cadr proc)))
544 665c255d 2023-08-04 jrmu primitive-procedures))
545 665c255d 2023-08-04 jrmu (define (apply-primitive-procedure proc args)
547 665c255d 2023-08-04 jrmu (primitive-implementation proc) args))
549 665c255d 2023-08-04 jrmu ;; execute application
551 665c255d 2023-08-04 jrmu (define (execute-application proc args succeed fail)
552 665c255d 2023-08-04 jrmu (cond ((primitive-procedure? proc)
553 665c255d 2023-08-04 jrmu (succeed (apply-primitive-procedure proc args)
555 665c255d 2023-08-04 jrmu ((compound-procedure? proc)
556 665c255d 2023-08-04 jrmu ((procedure-body proc)
557 665c255d 2023-08-04 jrmu (extend-environment (procedure-parameters proc)
559 665c255d 2023-08-04 jrmu (procedure-environment proc))
564 665c255d 2023-08-04 jrmu "Unknown procedure type -- EXECUTE-APPLICATION"
568 665c255d 2023-08-04 jrmu ;; driver-loop
569 665c255d 2023-08-04 jrmu (define (prompt-for-input string)
570 665c255d 2023-08-04 jrmu (newline) (newline) (display string) (newline))
571 665c255d 2023-08-04 jrmu (define (announce-output string)
572 665c255d 2023-08-04 jrmu (newline) (display string) (newline))
573 665c255d 2023-08-04 jrmu (define (user-print object)
574 665c255d 2023-08-04 jrmu (if (compound-procedure? object)
575 665c255d 2023-08-04 jrmu (display (list 'compound-procedure
576 665c255d 2023-08-04 jrmu (procedure-parameters object)
577 665c255d 2023-08-04 jrmu (procedure-body object)
578 665c255d 2023-08-04 jrmu '<procedure-env>))
579 665c255d 2023-08-04 jrmu (display object)))
580 665c255d 2023-08-04 jrmu (define (setup-environment)
581 665c255d 2023-08-04 jrmu (let ((initial-env
582 665c255d 2023-08-04 jrmu (extend-environment (primitive-procedure-names)
583 665c255d 2023-08-04 jrmu (primitive-procedure-objects)
584 665c255d 2023-08-04 jrmu the-empty-environment)))
585 665c255d 2023-08-04 jrmu (define-variable! 'true true initial-env)
586 665c255d 2023-08-04 jrmu (define-variable! 'false false initial-env)
587 665c255d 2023-08-04 jrmu initial-env))
588 665c255d 2023-08-04 jrmu (define the-global-environment (setup-environment))
590 665c255d 2023-08-04 jrmu (define input-prompt ";;; Amb-Eval input:")
591 665c255d 2023-08-04 jrmu (define output-prompt ";;; Amb-Eval value:")
592 665c255d 2023-08-04 jrmu (define (driver-loop)
593 665c255d 2023-08-04 jrmu (define (internal-loop try-again)
594 665c255d 2023-08-04 jrmu (prompt-for-input input-prompt)
595 665c255d 2023-08-04 jrmu (let ((input (read)))
596 665c255d 2023-08-04 jrmu (if (eq? input 'try-again)
597 665c255d 2023-08-04 jrmu (try-again)
600 665c255d 2023-08-04 jrmu (display ";;; Starting a new problem ")
601 665c255d 2023-08-04 jrmu (ambeval input
602 665c255d 2023-08-04 jrmu the-global-environment
603 665c255d 2023-08-04 jrmu ;; ambeval success
604 665c255d 2023-08-04 jrmu (lambda (val next-alternative)
605 665c255d 2023-08-04 jrmu (announce-output output-prompt)
606 665c255d 2023-08-04 jrmu (user-print val)
607 665c255d 2023-08-04 jrmu (internal-loop next-alternative))
608 665c255d 2023-08-04 jrmu ;; ambeval failure
610 665c255d 2023-08-04 jrmu (announce-output
611 665c255d 2023-08-04 jrmu ";;; There are no more values of")
612 665c255d 2023-08-04 jrmu (user-print input)
613 665c255d 2023-08-04 jrmu (driver-loop)))))))
614 665c255d 2023-08-04 jrmu (internal-loop
617 665c255d 2023-08-04 jrmu (display ";;; There is no current problem")
618 665c255d 2023-08-04 jrmu (driver-loop))))
621 665c255d 2023-08-04 jrmu ;; auxiliary
622 665c255d 2023-08-04 jrmu (define (test-case actual expected)
624 665c255d 2023-08-04 jrmu (display "Actual: ")
625 665c255d 2023-08-04 jrmu (display actual)
627 665c255d 2023-08-04 jrmu (display "Expected: ")
628 665c255d 2023-08-04 jrmu (display expected)
630 665c255d 2023-08-04 jrmu (define try-again
632 665c255d 2023-08-04 jrmu "No current problem"))
633 665c255d 2023-08-04 jrmu (define (geval exp) ;; eval globally
634 665c255d 2023-08-04 jrmu (if (eq? exp 'try-again)
635 665c255d 2023-08-04 jrmu (try-again)
636 665c255d 2023-08-04 jrmu (ambeval exp
637 665c255d 2023-08-04 jrmu the-global-environment
638 665c255d 2023-08-04 jrmu (lambda (val next-alternative)
639 665c255d 2023-08-04 jrmu (set! try-again next-alternative)
642 665c255d 2023-08-04 jrmu (set! try-again
644 665c255d 2023-08-04 jrmu "No current problem"))
645 665c255d 2023-08-04 jrmu "No alternatives"))))
646 665c255d 2023-08-04 jrmu (define (test-eval exp expected)
647 665c255d 2023-08-04 jrmu (test-case (geval exp) expected))
650 665c255d 2023-08-04 jrmu ;; test-suite
652 665c255d 2023-08-04 jrmu ;; procedure definitions
655 665c255d 2023-08-04 jrmu '(define (assoc key records)
656 665c255d 2023-08-04 jrmu (cond ((null? records) false)
657 665c255d 2023-08-04 jrmu ((equal? key (caar records)) (car records))
658 665c255d 2023-08-04 jrmu (else (assoc key (cdr records))))))
661 665c255d 2023-08-04 jrmu '(define (map proc list)
662 665c255d 2023-08-04 jrmu (if (null? list)
664 665c255d 2023-08-04 jrmu (cons (proc (car list))
665 665c255d 2023-08-04 jrmu (map proc (cdr list))))))
668 665c255d 2023-08-04 jrmu '(define (accumulate op initial sequence)
669 665c255d 2023-08-04 jrmu (if (null? sequence)
671 665c255d 2023-08-04 jrmu (op (car sequence)
672 665c255d 2023-08-04 jrmu (accumulate op initial (cdr sequence))))))
674 665c255d 2023-08-04 jrmu ;; ;; all special forms
675 665c255d 2023-08-04 jrmu (test-eval '(begin 5 6) 6)
676 665c255d 2023-08-04 jrmu (test-eval '10 10)
677 665c255d 2023-08-04 jrmu (geval '(define x 3))
678 665c255d 2023-08-04 jrmu (test-eval 'x 3)
679 665c255d 2023-08-04 jrmu (test-eval '(set! x -25) 'ok)
680 665c255d 2023-08-04 jrmu (test-eval 'x -25)
681 665c255d 2023-08-04 jrmu (geval '(define z (lambda (x y) (+ x (* x y)))))
682 665c255d 2023-08-04 jrmu (test-eval '(z 3 4) 15)
683 665c255d 2023-08-04 jrmu (test-eval '(cond ((= x -2) 'x=-2)
684 665c255d 2023-08-04 jrmu ((= x -25) 'x=-25)
685 665c255d 2023-08-04 jrmu (else 'failed))
687 665c255d 2023-08-04 jrmu (test-eval '(if true false true) false)
690 665c255d 2023-08-04 jrmu '(let ((x 4) (y 7))
691 665c255d 2023-08-04 jrmu (+ x y (* x y)))
692 665c255d 2023-08-04 jrmu (+ 4 7 (* 4 7)))
696 665c255d 2023-08-04 jrmu (geval '(define x (+ 3 8)))
697 665c255d 2023-08-04 jrmu (test-eval '(and 0 true x) 11)
698 665c255d 2023-08-04 jrmu (test-eval '(and 0 true x false) false)
699 665c255d 2023-08-04 jrmu (test-eval '(and 0 true x (set! x -2) false) false)
700 665c255d 2023-08-04 jrmu (test-eval 'x -2)
701 665c255d 2023-08-04 jrmu (test-eval '(and 0 true x false (set! x -5)) false)
702 665c255d 2023-08-04 jrmu (test-eval 'x -2)
703 665c255d 2023-08-04 jrmu (test-eval '(or false (set! x 25)) 'ok)
704 665c255d 2023-08-04 jrmu (test-eval 'x 25)
705 665c255d 2023-08-04 jrmu (test-eval '(or (set! x 2) (set! x 4)) 'ok)
706 665c255d 2023-08-04 jrmu (test-eval 'x 2)
707 665c255d 2023-08-04 jrmu (test-eval '(or false (set! x 25) true false) 'ok)
708 665c255d 2023-08-04 jrmu (test-eval 'x 25)
709 665c255d 2023-08-04 jrmu (test-eval '(or ((lambda (x) x) 5)) 5)
710 665c255d 2023-08-04 jrmu (test-eval '(or (begin (set! x (+ x 1)) x)) 26) ;; this fails because or->if repeats the same clause twice
712 665c255d 2023-08-04 jrmu (display "Failure expected")
718 665c255d 2023-08-04 jrmu '(cond ((assoc 'b '((a 1) (b 2))) => cadr)
719 665c255d 2023-08-04 jrmu (else false))
723 665c255d 2023-08-04 jrmu '(cond ((= 3 4) 'not-true)
724 665c255d 2023-08-04 jrmu ((= (* 2 4) 3) 'also-false)
725 665c255d 2023-08-04 jrmu ((map (lambda (x)
726 665c255d 2023-08-04 jrmu (* x (+ x 1)))
727 665c255d 2023-08-04 jrmu '(2 4 1 9))
729 665c255d 2023-08-04 jrmu (lambda (x)
730 665c255d 2023-08-04 jrmu (accumulate + 0 x)))
731 665c255d 2023-08-04 jrmu (else 'never-reach))
733 665c255d 2023-08-04 jrmu ;; '(6 20 2 90)
736 665c255d 2023-08-04 jrmu ;; procedure definition and application
738 665c255d 2023-08-04 jrmu '(define (factorial n)
739 665c255d 2023-08-04 jrmu (if (= n 0)
741 665c255d 2023-08-04 jrmu (* n (factorial (- n 1))))))
742 665c255d 2023-08-04 jrmu (test-eval '(factorial 5) 120)
747 665c255d 2023-08-04 jrmu '(map (lambda (x)
748 665c255d 2023-08-04 jrmu (* x (+ x 1)))
749 665c255d 2023-08-04 jrmu '(2 1 4 2 8 3))
750 665c255d 2023-08-04 jrmu '(6 2 20 6 72 12))
751 665c255d 2023-08-04 jrmu ;; accumulate
754 665c255d 2023-08-04 jrmu '(accumulate + 0 '(1 2 3 4 5))
757 665c255d 2023-08-04 jrmu ;; make-let
759 665c255d 2023-08-04 jrmu (make-let '(x y) '(3 5) '((+ x y)))
766 665c255d 2023-08-04 jrmu '(let ((x 3))
770 665c255d 2023-08-04 jrmu '(let ((x 3)
775 665c255d 2023-08-04 jrmu '(let ((x 3)
777 665c255d 2023-08-04 jrmu (+ (let ((x (+ y 2))
781 665c255d 2023-08-04 jrmu (+ (* 4 3) 3 2))
783 665c255d 2023-08-04 jrmu '(let ((x 6)
784 665c255d 2023-08-04 jrmu (y (let ((x 2))
786 665c255d 2023-08-04 jrmu (z (let ((a (* 3 2)))
795 665c255d 2023-08-04 jrmu '(let* ((x 3)
796 665c255d 2023-08-04 jrmu (y (+ x 2))
797 665c255d 2023-08-04 jrmu (z (+ x y 5)))
806 665c255d 2023-08-04 jrmu '(let* ((x 3))
807 665c255d 2023-08-04 jrmu (let* ((y 5))
812 665c255d 2023-08-04 jrmu '(let* ((x 3)
813 665c255d 2023-08-04 jrmu (y (+ x 1)))
814 665c255d 2023-08-04 jrmu (+ (let* ((x (+ y 2))
818 665c255d 2023-08-04 jrmu (+ (* 6 6) 3 4))
820 665c255d 2023-08-04 jrmu '(let* ((x 6)
821 665c255d 2023-08-04 jrmu (y (let* ((x 2)
822 665c255d 2023-08-04 jrmu (a (let* ((x (* 3 x)))
825 665c255d 2023-08-04 jrmu (z (+ x y)))
829 665c255d 2023-08-04 jrmu ;; named-let
832 665c255d 2023-08-04 jrmu '(let eight ()
838 665c255d 2023-08-04 jrmu '(let loop ((count 0))
839 665c255d 2023-08-04 jrmu (if (= 100 count)
841 665c255d 2023-08-04 jrmu (loop (+ count 1))))
844 665c255d 2023-08-04 jrmu '(define (prime? x)
845 665c255d 2023-08-04 jrmu (let prime-iter ((i 2))
846 665c255d 2023-08-04 jrmu (cond ((> (* i i) x) true)
847 665c255d 2023-08-04 jrmu ((= (remainder x i) 0) false)
848 665c255d 2023-08-04 jrmu (else (prime-iter (+ i 1)))))))
850 665c255d 2023-08-04 jrmu '(let primes ((x 2)
852 665c255d 2023-08-04 jrmu (cond ((= n 0) '())
853 665c255d 2023-08-04 jrmu ((prime? x)
855 665c255d 2023-08-04 jrmu (primes (+ x 1) (- n 1))))
856 665c255d 2023-08-04 jrmu (else (primes (+ x 1) n))))
857 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))
860 665c255d 2023-08-04 jrmu '(define (fib n)
861 665c255d 2023-08-04 jrmu (let fib-iter ((a 1)
864 665c255d 2023-08-04 jrmu (if (= count 0)
866 665c255d 2023-08-04 jrmu (fib-iter (+ a b) a (- count 1))))))
867 665c255d 2023-08-04 jrmu (test-eval '(fib 19) 4181)
871 665c255d 2023-08-04 jrmu '(let ((y 0))
872 665c255d 2023-08-04 jrmu (do ((x 0 (+ x 1)))
873 665c255d 2023-08-04 jrmu ((= x 5) y)
874 665c255d 2023-08-04 jrmu (set! y (+ y 1))))
885 665c255d 2023-08-04 jrmu '(let ((y 0))
887 665c255d 2023-08-04 jrmu ((= y 5) y)
888 665c255d 2023-08-04 jrmu (set! y (+ y 1))))
892 665c255d 2023-08-04 jrmu '(do ((y '(1 2 3 4)))
893 665c255d 2023-08-04 jrmu ((null? y))
894 665c255d 2023-08-04 jrmu (set! y (cdr y)))
897 665c255d 2023-08-04 jrmu '(let ((y 0))
898 665c255d 2023-08-04 jrmu (do ((x 0 (+ x 1)))
899 665c255d 2023-08-04 jrmu ((= x 5) y)
900 665c255d 2023-08-04 jrmu (set! y (+ y 1))))
903 665c255d 2023-08-04 jrmu '(let ((x '(1 3 5 7 9)))
904 665c255d 2023-08-04 jrmu (do ((x x (cdr x))
905 665c255d 2023-08-04 jrmu (sum 0 (+ sum (car x))))
906 665c255d 2023-08-04 jrmu ((null? x) sum)))
909 665c255d 2023-08-04 jrmu '(let ((z '()))
910 665c255d 2023-08-04 jrmu (do ((x '(1 2 3 4) (cdr x))
911 665c255d 2023-08-04 jrmu (y '(1 2 3 4 5 6 7 8) (cddr y)))
912 665c255d 2023-08-04 jrmu ((null? x) y x z)
913 665c255d 2023-08-04 jrmu (set! z (cons (car x) z))))
914 665c255d 2023-08-04 jrmu '(4 3 2 1))
918 665c255d 2023-08-04 jrmu ;; make-unbound!
919 665c255d 2023-08-04 jrmu ;; broken now due to scan-out-defines
921 665c255d 2023-08-04 jrmu ;; (test-eval
922 665c255d 2023-08-04 jrmu ;; '(let ((x 3))
923 665c255d 2023-08-04 jrmu ;; (let ((x 5))
924 665c255d 2023-08-04 jrmu ;; (make-unbound! x)
925 665c255d 2023-08-04 jrmu ;; (* x x)))
928 665c255d 2023-08-04 jrmu ;; (test-eval
929 665c255d 2023-08-04 jrmu ;; '(let ((x 3))
930 665c255d 2023-08-04 jrmu ;; (let ((x 5))
931 665c255d 2023-08-04 jrmu ;; (define y x)
932 665c255d 2023-08-04 jrmu ;; (make-unbound! x)
933 665c255d 2023-08-04 jrmu ;; (* y x)))
936 665c255d 2023-08-04 jrmu ;; (test-eval
937 665c255d 2023-08-04 jrmu ;; '(let ((y -1) (x 3))
938 665c255d 2023-08-04 jrmu ;; (let ((y 0.5) (x 5))
939 665c255d 2023-08-04 jrmu ;; (define a x)
940 665c255d 2023-08-04 jrmu ;; (define b y)
941 665c255d 2023-08-04 jrmu ;; (make-unbound! x)
942 665c255d 2023-08-04 jrmu ;; (make-unbound! y)
943 665c255d 2023-08-04 jrmu ;; (* a b x y)))
944 665c255d 2023-08-04 jrmu ;; (* 5 3 -1 0.5))
946 665c255d 2023-08-04 jrmu ;; (test-eval
947 665c255d 2023-08-04 jrmu ;; '(let ((x 3) (y 4))
948 665c255d 2023-08-04 jrmu ;; (let ((x 5))
949 665c255d 2023-08-04 jrmu ;; (make-unbound! x)
950 665c255d 2023-08-04 jrmu ;; (+ x 4)))
953 665c255d 2023-08-04 jrmu ;; (test-eval
954 665c255d 2023-08-04 jrmu ;; '(let ((a 1) (b 2) (c 3) (d 4))
955 665c255d 2023-08-04 jrmu ;; (make-unbound! b)
956 665c255d 2023-08-04 jrmu ;; (+ a c d))
957 665c255d 2023-08-04 jrmu ;; (+ 1 3 4))
959 665c255d 2023-08-04 jrmu ;; (test-eval
960 665c255d 2023-08-04 jrmu ;; '(let ((x 4) (y 5))
961 665c255d 2023-08-04 jrmu ;; (let ((a 1) (b 2) (c 3))
962 665c255d 2023-08-04 jrmu ;; (let ((x (+ a b)) (y (+ c a)))
963 665c255d 2023-08-04 jrmu ;; (make-unbound! x)
964 665c255d 2023-08-04 jrmu ;; (let ((a x) (b (+ x y)))
965 665c255d 2023-08-04 jrmu ;; (define z b)
966 665c255d 2023-08-04 jrmu ;; (make-unbound! b)
967 665c255d 2023-08-04 jrmu ;; (* (+ a z)
968 665c255d 2023-08-04 jrmu ;; (+ a b y))))))
969 665c255d 2023-08-04 jrmu ;; (* (+ 4 8)
970 665c255d 2023-08-04 jrmu ;; (+ 4 2 4)))
972 665c255d 2023-08-04 jrmu ;; x 3 -- y 4
973 665c255d 2023-08-04 jrmu ;; x 4 -- y 4
974 665c255d 2023-08-04 jrmu ;; a 4 -- b 4
975 665c255d 2023-08-04 jrmu ;; a 4 -- b 2
977 665c255d 2023-08-04 jrmu ;; scan-out-defines
980 665c255d 2023-08-04 jrmu '(define (f x)
981 665c255d 2023-08-04 jrmu (define (even? n)
982 665c255d 2023-08-04 jrmu (if (= n 0)
984 665c255d 2023-08-04 jrmu (odd? (- n 1))))
985 665c255d 2023-08-04 jrmu (define (odd? n)
986 665c255d 2023-08-04 jrmu (if (= n 0)
988 665c255d 2023-08-04 jrmu (even? (- n 1))))
989 665c255d 2023-08-04 jrmu (even? x)))
990 665c255d 2023-08-04 jrmu (test-eval '(f 5) false)
991 665c255d 2023-08-04 jrmu (test-eval '(f 10) true)
993 665c255d 2023-08-04 jrmu ;; ;; (geval
994 665c255d 2023-08-04 jrmu ;; ;; '(let ((x 5))
995 665c255d 2023-08-04 jrmu ;; ;; (define y x)
996 665c255d 2023-08-04 jrmu ;; ;; (define x 3)
997 665c255d 2023-08-04 jrmu ;; ;; (+ x y)))
998 665c255d 2023-08-04 jrmu ;; ;; signal an error because x is undefined if variables are scanned out
1000 665c255d 2023-08-04 jrmu ;; ;; letrec
1003 665c255d 2023-08-04 jrmu ;; '(define (f x)
1004 665c255d 2023-08-04 jrmu ;; (letrec ((even?
1005 665c255d 2023-08-04 jrmu ;; (lambda (n)
1006 665c255d 2023-08-04 jrmu ;; (if (= n 0)
1008 665c255d 2023-08-04 jrmu ;; (odd? (- n 1)))))
1010 665c255d 2023-08-04 jrmu ;; (lambda (n)
1011 665c255d 2023-08-04 jrmu ;; (if (= n 0)
1013 665c255d 2023-08-04 jrmu ;; (even? (- n 1))))))
1014 665c255d 2023-08-04 jrmu ;; (even? x))))
1015 665c255d 2023-08-04 jrmu ;; (test-eval '(f 11) false)
1016 665c255d 2023-08-04 jrmu ;; (test-eval '(f 16) true)
1018 665c255d 2023-08-04 jrmu ;; (test-eval
1019 665c255d 2023-08-04 jrmu ;; '(letrec ((fact
1020 665c255d 2023-08-04 jrmu ;; (lambda (n)
1021 665c255d 2023-08-04 jrmu ;; (if (= n 1)
1023 665c255d 2023-08-04 jrmu ;; (* n (fact (- n 1)))))))
1024 665c255d 2023-08-04 jrmu ;; (fact 10))
1025 665c255d 2023-08-04 jrmu ;; 3628800)
1028 665c255d 2023-08-04 jrmu (test-eval '(amb 1 2 3) 1)
1029 665c255d 2023-08-04 jrmu (test-eval 'try-again 2)
1030 665c255d 2023-08-04 jrmu (test-eval 'try-again 3)
1031 665c255d 2023-08-04 jrmu (test-eval 'try-again "No alternatives")
1032 665c255d 2023-08-04 jrmu (test-eval 'try-again "No current problem")
1033 665c255d 2023-08-04 jrmu (test-eval 'try-again "No current problem")
1034 665c255d 2023-08-04 jrmu (test-eval '(amb (amb 1 2) (amb 'a 'b))
1036 665c255d 2023-08-04 jrmu (test-eval 'try-again 2)
1037 665c255d 2023-08-04 jrmu (test-eval 'try-again 'a)
1038 665c255d 2023-08-04 jrmu (test-eval 'try-again 'b)
1039 665c255d 2023-08-04 jrmu (test-eval 'try-again "No alternatives")
1043 665c255d 2023-08-04 jrmu ;; Exercise 4.50. Implement a new special form ramb that is like amb except that it searches alternatives in a random order, rather than from left to right. Show how this can help with Alyssa's problem in exercise 4.49.
1045 665c255d 2023-08-04 jrmu (ramb <exp1> <exp2> ... <expN>)
1046 665c255d 2023-08-04 jrmu (define (ramb? exp)
1047 665c255d 2023-08-04 jrmu (tagged-list? exp 'ramb))
1048 665c255d 2023-08-04 jrmu (define (ramb-choices exp)
1049 665c255d 2023-08-04 jrmu (cdr exp))
