1 665c255d 2023-08-04 jrmu ;; (define apply-in-underlying-scheme apply)
3 665c255d 2023-08-04 jrmu (define (eval exp env)
4 665c255d 2023-08-04 jrmu ((analyze exp) env))
5 665c255d 2023-08-04 jrmu (define (analyze exp)
6 665c255d 2023-08-04 jrmu (cond ((self-evaluating? exp)
7 665c255d 2023-08-04 jrmu (analyze-self-evaluating exp))
8 665c255d 2023-08-04 jrmu ((quoted? exp) (analyze-quoted exp))
9 665c255d 2023-08-04 jrmu ((variable? exp) (analyze-variable exp))
10 665c255d 2023-08-04 jrmu ((assignment? exp) (analyze-assignment exp))
11 665c255d 2023-08-04 jrmu ((definition? exp) (analyze-definition exp))
12 665c255d 2023-08-04 jrmu ((if? exp) (analyze-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 ((begin? exp) (analyze-sequence (begin-actions exp)))
16 665c255d 2023-08-04 jrmu ((cond? exp) (analyze (cond->if exp)))
17 665c255d 2023-08-04 jrmu ((application? exp) (analyze-application exp))
19 665c255d 2023-08-04 jrmu (error "Unknown expression type -- ANALYZE" exp))))
20 665c255d 2023-08-04 jrmu (define (analyze-self-evaluating exp)
21 665c255d 2023-08-04 jrmu (lambda (env) exp))
22 665c255d 2023-08-04 jrmu (define (analyze-quoted exp)
23 665c255d 2023-08-04 jrmu (let ((qval (text-of-quotation exp)))
24 665c255d 2023-08-04 jrmu (lambda (env) qval)))
25 665c255d 2023-08-04 jrmu (define (analyze-variable exp)
26 665c255d 2023-08-04 jrmu (lambda (env) (lookup-variable-value exp env)))
27 665c255d 2023-08-04 jrmu (define (analyze-assignment exp)
28 665c255d 2023-08-04 jrmu (let ((var (assignment-variable exp))
29 665c255d 2023-08-04 jrmu (vproc (analyze (assignment-value exp))))
30 665c255d 2023-08-04 jrmu (lambda (env)
31 665c255d 2023-08-04 jrmu (set-variable-value! var (vproc env) env)
33 665c255d 2023-08-04 jrmu (define (analyze-definition exp)
34 665c255d 2023-08-04 jrmu (let ((var (definition-variable exp))
35 665c255d 2023-08-04 jrmu (vproc (analyze (definition-value exp))))
36 665c255d 2023-08-04 jrmu (lambda (env)
37 665c255d 2023-08-04 jrmu (define-variable! var (vproc env) env)
39 665c255d 2023-08-04 jrmu (define (analyze-if exp)
40 665c255d 2023-08-04 jrmu (let ((pproc (analyze (if-predicate exp)))
41 665c255d 2023-08-04 jrmu (cproc (analyze (if-consequent exp)))
42 665c255d 2023-08-04 jrmu (aproc (analyze (if-alternative exp))))
43 665c255d 2023-08-04 jrmu (lambda (env)
44 665c255d 2023-08-04 jrmu (if (true? (pproc env))
46 665c255d 2023-08-04 jrmu (aproc env)))))
47 665c255d 2023-08-04 jrmu (define (analyze-lambda exp)
48 665c255d 2023-08-04 jrmu (let ((vars (lambda-parameters exp))
49 665c255d 2023-08-04 jrmu (bproc (analyze-sequence (lambda-body exp))))
50 665c255d 2023-08-04 jrmu (lambda (env) (make-procedure vars bproc env))))
51 665c255d 2023-08-04 jrmu (define (analyze-sequence exps)
52 665c255d 2023-08-04 jrmu (define (sequentially proc1 proc2)
53 665c255d 2023-08-04 jrmu (lambda (env) (proc1 env) (proc2 env)))
54 665c255d 2023-08-04 jrmu (define (loop first-proc rest-procs)
55 665c255d 2023-08-04 jrmu (if (null? rest-procs)
57 665c255d 2023-08-04 jrmu (loop (sequentially first-proc (car rest-procs))
58 665c255d 2023-08-04 jrmu (cdr rest-procs))))
59 665c255d 2023-08-04 jrmu (let ((procs (map analyze exps)))
60 665c255d 2023-08-04 jrmu (if (null? procs)
61 665c255d 2023-08-04 jrmu (error "Empty sequence -- ANALYZE"))
62 665c255d 2023-08-04 jrmu (loop (car procs) (cdr procs))))
63 665c255d 2023-08-04 jrmu (define (analyze-application exp)
64 665c255d 2023-08-04 jrmu (let ((fproc (analyze (operator exp)))
65 665c255d 2023-08-04 jrmu (aprocs (map analyze (operands exp))))
66 665c255d 2023-08-04 jrmu (lambda (env)
67 665c255d 2023-08-04 jrmu (execute-application (fproc env)
68 665c255d 2023-08-04 jrmu (map (lambda (aproc) (aproc env))
70 665c255d 2023-08-04 jrmu (define (execute-application proc args)
71 665c255d 2023-08-04 jrmu (cond ((primitive-procedure? proc)
72 665c255d 2023-08-04 jrmu (apply-primitive-procedure proc args))
73 665c255d 2023-08-04 jrmu ((compound-procedure? proc)
74 665c255d 2023-08-04 jrmu ((procedure-body proc)
75 665c255d 2023-08-04 jrmu (extend-environment (procedure-parameters proc)
77 665c255d 2023-08-04 jrmu (procedure-environment proc))))
80 665c255d 2023-08-04 jrmu "Unknown procedure type -- EXECUTE-APPLICATION"
84 665c255d 2023-08-04 jrmu ;; (define (eval exp env)
85 665c255d 2023-08-04 jrmu ;; (cond ((self-evaluating? exp) exp)
86 665c255d 2023-08-04 jrmu ;; ((variable? exp) (lookup-variable-value exp env))
87 665c255d 2023-08-04 jrmu ;; ((quoted? exp) (text-of-quotation exp))
88 665c255d 2023-08-04 jrmu ;; ((assignment? exp) (eval-assignment exp env))
89 665c255d 2023-08-04 jrmu ;; ((definition? exp) (eval-definition exp env))
90 665c255d 2023-08-04 jrmu ;; ;; ((unbound? exp) (eval-unbound exp env))
91 665c255d 2023-08-04 jrmu ;; ((if? exp) (eval-if exp env))
92 665c255d 2023-08-04 jrmu ;; ((and? exp) (eval-and exp env))
93 665c255d 2023-08-04 jrmu ;; ((or? exp) (eval-or exp env))
94 665c255d 2023-08-04 jrmu ;; ((lambda? exp)
95 665c255d 2023-08-04 jrmu ;; (make-procedure (lambda-parameters exp)
96 665c255d 2023-08-04 jrmu ;; (lambda-body exp)
98 665c255d 2023-08-04 jrmu ;; ((begin? exp)
99 665c255d 2023-08-04 jrmu ;; (eval-sequence (begin-actions exp) env))
100 665c255d 2023-08-04 jrmu ;; ((cond? exp) (eval (cond->if exp) env))
101 665c255d 2023-08-04 jrmu ;; ((let? exp) (eval (let->combination exp) env))
102 665c255d 2023-08-04 jrmu ;; ((let*? exp) (eval (let*->nested-lets exp) env))
103 665c255d 2023-08-04 jrmu ;; ((named-let? exp) (eval (named-let->combination exp) env))
104 665c255d 2023-08-04 jrmu ;; ((letrec? exp) (eval (letrec->let exp) env))
105 665c255d 2023-08-04 jrmu ;; ((do? exp) (eval (do->combination exp) env))
106 665c255d 2023-08-04 jrmu ;; ((application? exp)
107 665c255d 2023-08-04 jrmu ;; (apply (eval (operator exp) env)
108 665c255d 2023-08-04 jrmu ;; (list-of-values (operands exp) env)))
110 665c255d 2023-08-04 jrmu ;; (error "Unknown expression type -- EVAL" exp))))
111 665c255d 2023-08-04 jrmu ;; (define (apply procedure arguments)
112 665c255d 2023-08-04 jrmu ;; (cond ((primitive-procedure? procedure)
113 665c255d 2023-08-04 jrmu ;; (apply-primitive-procedure procedure arguments))
114 665c255d 2023-08-04 jrmu ;; ((compound-procedure? procedure)
115 665c255d 2023-08-04 jrmu ;; (eval-sequence
116 665c255d 2023-08-04 jrmu ;; (procedure-body procedure)
117 665c255d 2023-08-04 jrmu ;; (extend-environment
118 665c255d 2023-08-04 jrmu ;; (procedure-parameters procedure)
119 665c255d 2023-08-04 jrmu ;; arguments
120 665c255d 2023-08-04 jrmu ;; (procedure-environment procedure))))
123 665c255d 2023-08-04 jrmu ;; "Unknown procedure type -- APPLY" procedure))))
125 665c255d 2023-08-04 jrmu (define (list-of-values exps env)
126 665c255d 2023-08-04 jrmu (if (no-operands? exps)
128 665c255d 2023-08-04 jrmu (cons (eval (first-operand exps) env)
129 665c255d 2023-08-04 jrmu (list-of-values (rest-operands exps) env))))
131 665c255d 2023-08-04 jrmu (define (tagged-list? exp tag)
132 665c255d 2023-08-04 jrmu (if (pair? exp)
133 665c255d 2023-08-04 jrmu (eq? (car exp) tag)
136 665c255d 2023-08-04 jrmu ;; self-evaluating/variable/quoted
137 665c255d 2023-08-04 jrmu (define (self-evaluating? exp)
138 665c255d 2023-08-04 jrmu (cond ((number? exp) true)
139 665c255d 2023-08-04 jrmu ((string? exp) true)
140 665c255d 2023-08-04 jrmu (else false)))
141 665c255d 2023-08-04 jrmu (define (variable? exp) (symbol? exp))
142 665c255d 2023-08-04 jrmu (define (quoted? exp)
143 665c255d 2023-08-04 jrmu (tagged-list? exp 'quote))
144 665c255d 2023-08-04 jrmu (define (text-of-quotation exp) (cadr exp))
146 665c255d 2023-08-04 jrmu ;; assignment/definition
147 665c255d 2023-08-04 jrmu (define (assignment? exp)
148 665c255d 2023-08-04 jrmu (tagged-list? exp 'set!))
149 665c255d 2023-08-04 jrmu (define (assignment-variable exp) (cadr exp))
150 665c255d 2023-08-04 jrmu (define (assignment-value exp) (caddr exp))
151 665c255d 2023-08-04 jrmu (define (make-assignment var val)
152 665c255d 2023-08-04 jrmu (list 'set! var val))
153 665c255d 2023-08-04 jrmu (define (definition? exp)
154 665c255d 2023-08-04 jrmu (tagged-list? exp 'define))
155 665c255d 2023-08-04 jrmu (define (definition-variable exp)
156 665c255d 2023-08-04 jrmu (if (symbol? (cadr exp))
158 665c255d 2023-08-04 jrmu (caadr exp)))
159 665c255d 2023-08-04 jrmu (define (definition-value exp)
160 665c255d 2023-08-04 jrmu (if (symbol? (cadr exp))
161 665c255d 2023-08-04 jrmu (caddr exp)
162 665c255d 2023-08-04 jrmu (make-lambda (cdadr exp) ; formal parameters
163 665c255d 2023-08-04 jrmu (cddr exp)))) ; body
164 665c255d 2023-08-04 jrmu (define (eval-assignment exp env)
165 665c255d 2023-08-04 jrmu (set-variable-value! (assignment-variable exp)
166 665c255d 2023-08-04 jrmu (eval (assignment-value exp) env)
169 665c255d 2023-08-04 jrmu (define (eval-definition exp env)
170 665c255d 2023-08-04 jrmu (define-variable! (definition-variable exp)
171 665c255d 2023-08-04 jrmu (eval (definition-value exp) env)
174 665c255d 2023-08-04 jrmu (define (make-definition var val)
175 665c255d 2023-08-04 jrmu `(define ,var ,val))
177 665c255d 2023-08-04 jrmu ;; make-unbound!
179 665c255d 2023-08-04 jrmu ;; (define (unbound? exp)
180 665c255d 2023-08-04 jrmu ;; (tagged-list? exp 'make-unbound!))
181 665c255d 2023-08-04 jrmu ;; (define (unbound-var exp)
182 665c255d 2023-08-04 jrmu ;; (cadr exp))
183 665c255d 2023-08-04 jrmu ;; (define (eval-unbound exp env)
184 665c255d 2023-08-04 jrmu ;; (remove-binding-from-frame! (unbound-var exp) (first-frame env)))
188 665c255d 2023-08-04 jrmu ;; if/and/or
189 665c255d 2023-08-04 jrmu (define (if? exp) (tagged-list? exp 'if))
190 665c255d 2023-08-04 jrmu (define (if-predicate exp) (cadr exp))
191 665c255d 2023-08-04 jrmu (define (if-consequent exp) (caddr exp))
192 665c255d 2023-08-04 jrmu (define (if-alternative exp)
193 665c255d 2023-08-04 jrmu (if (not (null? (cdddr exp)))
194 665c255d 2023-08-04 jrmu (cadddr exp)
196 665c255d 2023-08-04 jrmu (define (make-if predicate consequent alternative)
197 665c255d 2023-08-04 jrmu (list 'if predicate consequent alternative))
198 665c255d 2023-08-04 jrmu (define (eval-if exp env)
199 665c255d 2023-08-04 jrmu (if (true? (eval (if-predicate exp) env))
200 665c255d 2023-08-04 jrmu (eval (if-consequent exp) env)
201 665c255d 2023-08-04 jrmu (eval (if-alternative exp) env)))
203 665c255d 2023-08-04 jrmu (define (and? exp)
204 665c255d 2023-08-04 jrmu (tagged-list? exp 'and))
205 665c255d 2023-08-04 jrmu (define (and-clauses exp)
207 665c255d 2023-08-04 jrmu (define (or? exp)
208 665c255d 2023-08-04 jrmu (tagged-list? exp 'or))
209 665c255d 2023-08-04 jrmu (define (or-clauses exp)
211 665c255d 2023-08-04 jrmu (define (eval-and exp env)
212 665c255d 2023-08-04 jrmu (define (eval-clauses clauses)
213 665c255d 2023-08-04 jrmu (cond ((null? clauses) true)
214 665c255d 2023-08-04 jrmu ((null? (cdr clauses)) (eval (car clauses) env))
215 665c255d 2023-08-04 jrmu (else (and (eval (car clauses) env)
216 665c255d 2023-08-04 jrmu (eval-clauses (cdr clauses))))))
217 665c255d 2023-08-04 jrmu (eval-clauses (and-clauses exp)))
218 665c255d 2023-08-04 jrmu (define (eval-or exp env)
219 665c255d 2023-08-04 jrmu (define (eval-clauses clauses)
220 665c255d 2023-08-04 jrmu (if (null? clauses)
222 665c255d 2023-08-04 jrmu (or (eval (car clauses) env)
223 665c255d 2023-08-04 jrmu (eval-clauses (cdr clauses)))))
224 665c255d 2023-08-04 jrmu (eval-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))))
300 665c255d 2023-08-04 jrmu (define (make-application op args)
301 665c255d 2023-08-04 jrmu (cons op args))
303 665c255d 2023-08-04 jrmu (define (let*? exp)
304 665c255d 2023-08-04 jrmu (tagged-list? exp 'let*))
305 665c255d 2023-08-04 jrmu (define let*-vars let-vars)
306 665c255d 2023-08-04 jrmu (define let*-vals let-vals)
307 665c255d 2023-08-04 jrmu (define let*-body let-body)
308 665c255d 2023-08-04 jrmu (define (let*->nested-lets exp)
309 665c255d 2023-08-04 jrmu (define (expand-lets vars vals)
310 665c255d 2023-08-04 jrmu (if (null? (cdr vars))
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 (let*-body exp))
314 665c255d 2023-08-04 jrmu (make-let (list (car vars))
315 665c255d 2023-08-04 jrmu (list (car vals))
316 665c255d 2023-08-04 jrmu (list (expand-lets (cdr vars) (cdr vals))))))
317 665c255d 2023-08-04 jrmu (let ((vars (let*-vars exp))
318 665c255d 2023-08-04 jrmu (vals (let*-vals exp)))
319 665c255d 2023-08-04 jrmu (if (null? vars)
320 665c255d 2023-08-04 jrmu (sequence->exp (let*-body exp))
321 665c255d 2023-08-04 jrmu (expand-lets vars vals))))
324 665c255d 2023-08-04 jrmu (define (do? exp)
325 665c255d 2023-08-04 jrmu (tagged-list? exp 'do))
326 665c255d 2023-08-04 jrmu (define (do-vars exp)
327 665c255d 2023-08-04 jrmu (map car (cadr exp)))
328 665c255d 2023-08-04 jrmu (define (do-inits exp)
329 665c255d 2023-08-04 jrmu (map cadr (cadr exp)))
330 665c255d 2023-08-04 jrmu (define (do-steps exp)
331 665c255d 2023-08-04 jrmu (map (lambda (var-init-step)
332 665c255d 2023-08-04 jrmu (if (null? (cddr var-init-step))
333 665c255d 2023-08-04 jrmu (car var-init-step)
334 665c255d 2023-08-04 jrmu (caddr var-init-step)))
335 665c255d 2023-08-04 jrmu (cadr exp)))
336 665c255d 2023-08-04 jrmu (define (do-test exp)
337 665c255d 2023-08-04 jrmu (caaddr exp))
338 665c255d 2023-08-04 jrmu (define (do-expressions exp)
339 665c255d 2023-08-04 jrmu (if (null? (cdaddr exp))
340 665c255d 2023-08-04 jrmu (caddr exp)
341 665c255d 2023-08-04 jrmu (cdaddr exp)))
342 665c255d 2023-08-04 jrmu (define (do-commands exp)
343 665c255d 2023-08-04 jrmu (cdddr exp))
344 665c255d 2023-08-04 jrmu (define (do->combination exp)
345 665c255d 2023-08-04 jrmu (make-named-let
347 665c255d 2023-08-04 jrmu (do-vars exp)
348 665c255d 2023-08-04 jrmu (do-inits exp)
351 665c255d 2023-08-04 jrmu (do-test exp)
352 665c255d 2023-08-04 jrmu (sequence->exp (do-expressions exp))
353 665c255d 2023-08-04 jrmu (sequence->exp
354 665c255d 2023-08-04 jrmu (append (do-commands exp)
355 665c255d 2023-08-04 jrmu (list (make-application
357 665c255d 2023-08-04 jrmu (do-steps exp)))))))))
360 665c255d 2023-08-04 jrmu ;; begin/sequence
361 665c255d 2023-08-04 jrmu (define (begin? exp) (tagged-list? exp 'begin))
362 665c255d 2023-08-04 jrmu (define (begin-actions exp) (cdr exp))
363 665c255d 2023-08-04 jrmu (define (last-exp? seq) (null? (cdr seq)))
364 665c255d 2023-08-04 jrmu (define (first-exp seq) (car seq))
365 665c255d 2023-08-04 jrmu (define (rest-exps seq) (cdr seq))
366 665c255d 2023-08-04 jrmu (define (sequence->exp seq)
367 665c255d 2023-08-04 jrmu (cond ((null? seq) seq)
368 665c255d 2023-08-04 jrmu ((last-exp? seq) (first-exp seq))
369 665c255d 2023-08-04 jrmu (else (make-begin seq))))
370 665c255d 2023-08-04 jrmu (define (make-begin seq) (cons 'begin seq))
371 665c255d 2023-08-04 jrmu (define (eval-sequence exps env)
372 665c255d 2023-08-04 jrmu (cond ((last-exp? exps) (eval (first-exp exps) env))
373 665c255d 2023-08-04 jrmu (else (eval (first-exp exps) env)
374 665c255d 2023-08-04 jrmu (eval-sequence (rest-exps exps) env))))
376 665c255d 2023-08-04 jrmu ;; application
377 665c255d 2023-08-04 jrmu (define (application? exp) (pair? exp))
378 665c255d 2023-08-04 jrmu (define (operator exp) (car exp))
379 665c255d 2023-08-04 jrmu (define (operands exp) (cdr exp))
380 665c255d 2023-08-04 jrmu (define (no-operands? ops) (null? ops))
381 665c255d 2023-08-04 jrmu (define (first-operand ops) (car ops))
382 665c255d 2023-08-04 jrmu (define (rest-operands ops) (cdr ops))
385 665c255d 2023-08-04 jrmu (define (cond? exp) (tagged-list? exp 'cond))
386 665c255d 2023-08-04 jrmu (define (cond-clauses exp) (cdr exp))
387 665c255d 2023-08-04 jrmu (define (cond-else-clause? clause)
388 665c255d 2023-08-04 jrmu (eq? (cond-predicate clause) 'else))
389 665c255d 2023-08-04 jrmu (define (cond-predicate clause) (car clause))
390 665c255d 2023-08-04 jrmu (define (cond-actions clause) (cdr clause))
391 665c255d 2023-08-04 jrmu (define (cond-extended-clause? clause)
392 665c255d 2023-08-04 jrmu (and (not (null? (cdr clause))) (eq? (cadr clause) '=>)))
393 665c255d 2023-08-04 jrmu (define (cond-extended-proc clause)
394 665c255d 2023-08-04 jrmu (caddr clause))
395 665c255d 2023-08-04 jrmu (define (cond->if exp)
396 665c255d 2023-08-04 jrmu (expand-clauses (cond-clauses exp)))
397 665c255d 2023-08-04 jrmu (define (expand-clauses clauses)
398 665c255d 2023-08-04 jrmu (if (null? clauses)
399 665c255d 2023-08-04 jrmu 'false ; no else clause
400 665c255d 2023-08-04 jrmu (let ((first (car clauses))
401 665c255d 2023-08-04 jrmu (rest (cdr clauses)))
402 665c255d 2023-08-04 jrmu (if (cond-else-clause? first)
403 665c255d 2023-08-04 jrmu (if (null? rest)
404 665c255d 2023-08-04 jrmu (sequence->exp (cond-actions first))
405 665c255d 2023-08-04 jrmu (error "ELSE clause isn't last -- COND->IF"
407 665c255d 2023-08-04 jrmu (if (cond-extended-clause? first)
408 665c255d 2023-08-04 jrmu (make-if (cond-predicate first)
409 665c255d 2023-08-04 jrmu (make-application
410 665c255d 2023-08-04 jrmu (cond-extended-proc first)
411 665c255d 2023-08-04 jrmu (list (cond-predicate first)))
412 665c255d 2023-08-04 jrmu (expand-clauses rest))
413 665c255d 2023-08-04 jrmu (make-if (cond-predicate first)
414 665c255d 2023-08-04 jrmu (sequence->exp (cond-actions first))
415 665c255d 2023-08-04 jrmu (expand-clauses rest)))))))
416 665c255d 2023-08-04 jrmu (define (true? x)
417 665c255d 2023-08-04 jrmu (not (eq? x false)))
418 665c255d 2023-08-04 jrmu (define (false? x)
419 665c255d 2023-08-04 jrmu (eq? x false))
421 665c255d 2023-08-04 jrmu ;; procedure
422 665c255d 2023-08-04 jrmu (define (make-procedure parameters body env)
423 665c255d 2023-08-04 jrmu (list 'procedure parameters body env))
424 665c255d 2023-08-04 jrmu ;; (define (scan-out-defines body)
425 665c255d 2023-08-04 jrmu ;; (let* ((definitions (filter definition? body))
426 665c255d 2023-08-04 jrmu ;; (vars (map definition-variable definitions))
427 665c255d 2023-08-04 jrmu ;; (unassigneds (map (lambda (var) ''*unassigned*)
429 665c255d 2023-08-04 jrmu ;; (vals (map definition-value definitions))
430 665c255d 2023-08-04 jrmu ;; (assignments
431 665c255d 2023-08-04 jrmu ;; (map (lambda (var val)
432 665c255d 2023-08-04 jrmu ;; (make-assignment var val))
433 665c255d 2023-08-04 jrmu ;; vars vals))
434 665c255d 2023-08-04 jrmu ;; (exps (remove definition? body)))
435 665c255d 2023-08-04 jrmu ;; (if (null? definitions)
438 665c255d 2023-08-04 jrmu ;; (make-let vars
439 665c255d 2023-08-04 jrmu ;; unassigneds
440 665c255d 2023-08-04 jrmu ;; (append assignments exps))))))
441 665c255d 2023-08-04 jrmu (define (compound-procedure? p)
442 665c255d 2023-08-04 jrmu (tagged-list? p 'procedure))
443 665c255d 2023-08-04 jrmu (define (procedure-parameters p) (cadr p))
444 665c255d 2023-08-04 jrmu (define (procedure-body p) (caddr p))
445 665c255d 2023-08-04 jrmu (define (procedure-environment p) (cadddr p))
447 665c255d 2023-08-04 jrmu ;; environment
448 665c255d 2023-08-04 jrmu (define (enclosing-environment env) (cdr env))
449 665c255d 2023-08-04 jrmu (define (first-frame env) (car env))
450 665c255d 2023-08-04 jrmu (define the-empty-environment '())
451 665c255d 2023-08-04 jrmu (define (make-frame variables values)
452 665c255d 2023-08-04 jrmu (cons variables values))
453 665c255d 2023-08-04 jrmu (define (frame-variables frame) (car frame))
454 665c255d 2023-08-04 jrmu (define (frame-values frame) (cdr frame))
455 665c255d 2023-08-04 jrmu (define (add-binding-to-frame! var val frame)
456 665c255d 2023-08-04 jrmu (set-car! frame (cons var (car frame)))
457 665c255d 2023-08-04 jrmu (set-cdr! frame (cons val (cdr frame))))
458 665c255d 2023-08-04 jrmu (define (extend-environment vars vals base-env)
459 665c255d 2023-08-04 jrmu (if (= (length vars) (length vals))
460 665c255d 2023-08-04 jrmu (cons (make-frame vars vals) base-env)
461 665c255d 2023-08-04 jrmu (if (< (length vars) (length vals))
462 665c255d 2023-08-04 jrmu (error "Too many arguments supplied" vars vals)
463 665c255d 2023-08-04 jrmu (error "Too few arguments supplied" vars vals))))
464 665c255d 2023-08-04 jrmu (define (lookup-variable-value var env)
465 665c255d 2023-08-04 jrmu (define (env-loop env)
466 665c255d 2023-08-04 jrmu (define (scan vars vals)
467 665c255d 2023-08-04 jrmu (cond ((null? vars)
468 665c255d 2023-08-04 jrmu (env-loop (enclosing-environment env)))
469 665c255d 2023-08-04 jrmu ((eq? var (car vars))
470 665c255d 2023-08-04 jrmu (let ((val (car vals)))
471 665c255d 2023-08-04 jrmu (if (eq? val '*unassigned*)
472 665c255d 2023-08-04 jrmu (error "Var not yet defined -- LOOKUP-VARIABLE-VALUE" var)
474 665c255d 2023-08-04 jrmu (else (scan (cdr vars) (cdr vals)))))
475 665c255d 2023-08-04 jrmu (if (eq? env the-empty-environment)
476 665c255d 2023-08-04 jrmu (error "Unbound variable" var)
477 665c255d 2023-08-04 jrmu (let ((frame (first-frame env)))
478 665c255d 2023-08-04 jrmu (scan (frame-variables frame)
479 665c255d 2023-08-04 jrmu (frame-values frame)))))
480 665c255d 2023-08-04 jrmu (env-loop env))
481 665c255d 2023-08-04 jrmu (define (set-variable-value! var val env)
482 665c255d 2023-08-04 jrmu (define (env-loop env)
483 665c255d 2023-08-04 jrmu (define (scan vars vals)
484 665c255d 2023-08-04 jrmu (cond ((null? vars)
485 665c255d 2023-08-04 jrmu (env-loop (enclosing-environment env)))
486 665c255d 2023-08-04 jrmu ((eq? var (car vars))
487 665c255d 2023-08-04 jrmu (set-car! vals val))
488 665c255d 2023-08-04 jrmu (else (scan (cdr vars) (cdr vals)))))
489 665c255d 2023-08-04 jrmu (if (eq? env the-empty-environment)
490 665c255d 2023-08-04 jrmu (error "Unbound variable -- SET!" var)
491 665c255d 2023-08-04 jrmu (let ((frame (first-frame env)))
492 665c255d 2023-08-04 jrmu (scan (frame-variables frame)
493 665c255d 2023-08-04 jrmu (frame-values frame)))))
494 665c255d 2023-08-04 jrmu (env-loop env))
495 665c255d 2023-08-04 jrmu (define (define-variable! var val env)
496 665c255d 2023-08-04 jrmu (let ((frame (first-frame env)))
497 665c255d 2023-08-04 jrmu (define (scan vars vals)
498 665c255d 2023-08-04 jrmu (cond ((null? vars)
499 665c255d 2023-08-04 jrmu (add-binding-to-frame! var val frame))
500 665c255d 2023-08-04 jrmu ((eq? var (car vars))
501 665c255d 2023-08-04 jrmu (set-car! vals val))
502 665c255d 2023-08-04 jrmu (else (scan (cdr vars) (cdr vals)))))
503 665c255d 2023-08-04 jrmu (scan (frame-variables frame)
504 665c255d 2023-08-04 jrmu (frame-values frame))))
506 665c255d 2023-08-04 jrmu (define (remove-binding-from-frame! var frame)
507 665c255d 2023-08-04 jrmu (define (scan vars vals)
508 665c255d 2023-08-04 jrmu (cond ((null? (cdr vars))
509 665c255d 2023-08-04 jrmu (error "Binding not found -- REMOVE-BINDING-FROM-FRAME!" var))
510 665c255d 2023-08-04 jrmu ((eq? var (cadr vars))
511 665c255d 2023-08-04 jrmu (set-cdr! vars (cddr vars))
512 665c255d 2023-08-04 jrmu (set-cdr! vals (cddr vals)))
513 665c255d 2023-08-04 jrmu (else (scan (cdr vars) (cdr vals)))))
514 665c255d 2023-08-04 jrmu (let ((vars (frame-variables frame))
515 665c255d 2023-08-04 jrmu (vals (frame-values frame)))
516 665c255d 2023-08-04 jrmu (if (eq? var (car vars))
517 665c255d 2023-08-04 jrmu (begin (set-car! frame (cdr vars))
518 665c255d 2023-08-04 jrmu (set-cdr! frame (cdr vals)))
519 665c255d 2023-08-04 jrmu (scan vars vals))))
521 665c255d 2023-08-04 jrmu ;; primitives
522 665c255d 2023-08-04 jrmu (define (primitive-procedure? proc)
523 665c255d 2023-08-04 jrmu (tagged-list? proc 'primitive))
524 665c255d 2023-08-04 jrmu (define (primitive-implementation proc) (cadr proc))
525 665c255d 2023-08-04 jrmu (define primitive-procedures
526 665c255d 2023-08-04 jrmu (list (list 'car car)
527 665c255d 2023-08-04 jrmu (list 'cdr cdr)
528 665c255d 2023-08-04 jrmu (list 'caar caar)
529 665c255d 2023-08-04 jrmu (list 'cadr cadr)
530 665c255d 2023-08-04 jrmu (list 'cddr cddr)
531 665c255d 2023-08-04 jrmu (list 'cons cons)
532 665c255d 2023-08-04 jrmu (list 'null? null?)
533 665c255d 2023-08-04 jrmu (list '* *)
534 665c255d 2023-08-04 jrmu (list '/ /)
535 665c255d 2023-08-04 jrmu (list '+ +)
536 665c255d 2023-08-04 jrmu (list '- -)
537 665c255d 2023-08-04 jrmu (list '= =)
538 665c255d 2023-08-04 jrmu (list '< <)
539 665c255d 2023-08-04 jrmu (list '> >)
540 665c255d 2023-08-04 jrmu (list '<= <=)
541 665c255d 2023-08-04 jrmu (list '>= >=)
542 665c255d 2023-08-04 jrmu (list 'remainder remainder)
543 665c255d 2023-08-04 jrmu (list 'eq? eq?)
544 665c255d 2023-08-04 jrmu (list 'equal? equal?)
545 665c255d 2023-08-04 jrmu (list 'display display)))
546 665c255d 2023-08-04 jrmu (define (primitive-procedure-names)
548 665c255d 2023-08-04 jrmu primitive-procedures))
549 665c255d 2023-08-04 jrmu (define (primitive-procedure-objects)
550 665c255d 2023-08-04 jrmu (map (lambda (proc) (list 'primitive (cadr proc)))
551 665c255d 2023-08-04 jrmu primitive-procedures))
552 665c255d 2023-08-04 jrmu (define (apply-primitive-procedure proc args)
553 665c255d 2023-08-04 jrmu (apply-in-underlying-scheme
554 665c255d 2023-08-04 jrmu (primitive-implementation proc) args))
556 665c255d 2023-08-04 jrmu ;; driver-loop
557 665c255d 2023-08-04 jrmu (define input-prompt ";;; M-Eval input:")
558 665c255d 2023-08-04 jrmu (define output-prompt ";;; M-Eval value:")
559 665c255d 2023-08-04 jrmu (define (driver-loop)
560 665c255d 2023-08-04 jrmu (prompt-for-input input-prompt)
561 665c255d 2023-08-04 jrmu (let ((input (read)))
562 665c255d 2023-08-04 jrmu (let ((output (eval input the-global-environment)))
563 665c255d 2023-08-04 jrmu (announce-output output-prompt)
564 665c255d 2023-08-04 jrmu (user-print output)))
565 665c255d 2023-08-04 jrmu (driver-loop))
566 665c255d 2023-08-04 jrmu (define (prompt-for-input string)
567 665c255d 2023-08-04 jrmu (newline) (newline) (display string) (newline))
569 665c255d 2023-08-04 jrmu (define (announce-output string)
570 665c255d 2023-08-04 jrmu (newline) (display string) (newline))
571 665c255d 2023-08-04 jrmu (define (user-print object)
572 665c255d 2023-08-04 jrmu (if (compound-procedure? object)
573 665c255d 2023-08-04 jrmu (display (list 'compound-procedure
574 665c255d 2023-08-04 jrmu (procedure-parameters object)
575 665c255d 2023-08-04 jrmu (procedure-body object)
576 665c255d 2023-08-04 jrmu '<procedure-env>))
577 665c255d 2023-08-04 jrmu (display object)))
578 665c255d 2023-08-04 jrmu (define (setup-environment)
579 665c255d 2023-08-04 jrmu (let ((initial-env
580 665c255d 2023-08-04 jrmu (extend-environment (primitive-procedure-names)
581 665c255d 2023-08-04 jrmu (primitive-procedure-objects)
582 665c255d 2023-08-04 jrmu the-empty-environment)))
583 665c255d 2023-08-04 jrmu (define-variable! 'true true initial-env)
584 665c255d 2023-08-04 jrmu (define-variable! 'false false initial-env)
585 665c255d 2023-08-04 jrmu initial-env))
586 665c255d 2023-08-04 jrmu (define the-global-environment (setup-environment))
588 665c255d 2023-08-04 jrmu ;; auxiliary
589 665c255d 2023-08-04 jrmu (define (test-case actual expected)
591 665c255d 2023-08-04 jrmu (display "Actual: ")
592 665c255d 2023-08-04 jrmu (display actual)
594 665c255d 2023-08-04 jrmu (display "Expected: ")
595 665c255d 2023-08-04 jrmu (display expected)
597 665c255d 2023-08-04 jrmu (define (geval exp) ;; eval globally
598 665c255d 2023-08-04 jrmu (eval exp the-global-environment))
599 665c255d 2023-08-04 jrmu (define (test-eval exp expected)
600 665c255d 2023-08-04 jrmu (test-case (geval exp) expected))
604 665c255d 2023-08-04 jrmu ;; test-suite
606 665c255d 2023-08-04 jrmu ;; procedure definitions
609 665c255d 2023-08-04 jrmu '(define (assoc key records)
610 665c255d 2023-08-04 jrmu (cond ((null? records) false)
611 665c255d 2023-08-04 jrmu ((equal? key (caar records)) (car records))
612 665c255d 2023-08-04 jrmu (else (assoc key (cdr records))))))
615 665c255d 2023-08-04 jrmu '(define (map proc list)
616 665c255d 2023-08-04 jrmu (if (null? list)
618 665c255d 2023-08-04 jrmu (cons (proc (car list))
619 665c255d 2023-08-04 jrmu (map proc (cdr list))))))
622 665c255d 2023-08-04 jrmu '(define (accumulate op initial sequence)
623 665c255d 2023-08-04 jrmu (if (null? sequence)
625 665c255d 2023-08-04 jrmu (op (car sequence)
626 665c255d 2023-08-04 jrmu (accumulate op initial (cdr sequence))))))
628 665c255d 2023-08-04 jrmu ;; all special forms
629 665c255d 2023-08-04 jrmu (test-eval '(begin 5 6) 6)
630 665c255d 2023-08-04 jrmu (test-eval '10 10)
631 665c255d 2023-08-04 jrmu (geval '(define x 3))
632 665c255d 2023-08-04 jrmu (test-eval 'x 3)
633 665c255d 2023-08-04 jrmu (test-eval '(set! x -25) 'ok)
634 665c255d 2023-08-04 jrmu (test-eval 'x -25)
635 665c255d 2023-08-04 jrmu (geval '(define z (lambda (x y) (+ x (* x y)))))
636 665c255d 2023-08-04 jrmu (test-eval '(z 3 4) 15)
637 665c255d 2023-08-04 jrmu (test-eval '(cond ((= x -2) 'x=-2)
638 665c255d 2023-08-04 jrmu ((= x -25) 'x=-25)
639 665c255d 2023-08-04 jrmu (else 'failed))
641 665c255d 2023-08-04 jrmu (test-eval '(if true false true) false)
644 665c255d 2023-08-04 jrmu '(let ((x 4) (y 7))
645 665c255d 2023-08-04 jrmu (+ x y (* x y)))
646 665c255d 2023-08-04 jrmu (+ 4 7 (* 4 7)))
650 665c255d 2023-08-04 jrmu (geval '(define x (+ 3 8)))
651 665c255d 2023-08-04 jrmu (test-eval '(and 0 true x) 11)
652 665c255d 2023-08-04 jrmu (test-eval '(and 0 true x false) false)
653 665c255d 2023-08-04 jrmu (test-eval '(and 0 true x (set! x -2) false) false)
654 665c255d 2023-08-04 jrmu (test-eval 'x -2)
655 665c255d 2023-08-04 jrmu (test-eval '(and 0 true x false (set! x -5)) false)
656 665c255d 2023-08-04 jrmu (test-eval 'x -2)
657 665c255d 2023-08-04 jrmu (test-eval '(or false (set! x 25)) 'ok)
658 665c255d 2023-08-04 jrmu (test-eval 'x 25)
659 665c255d 2023-08-04 jrmu (test-eval '(or (set! x 2) (set! x 4)) 'ok)
660 665c255d 2023-08-04 jrmu (test-eval 'x 2)
661 665c255d 2023-08-04 jrmu (test-eval '(or false (set! x 25) true false) 'ok)
662 665c255d 2023-08-04 jrmu (test-eval 'x 25)
663 665c255d 2023-08-04 jrmu (test-eval '(or ((lambda (x) x) 5)) 5)
664 665c255d 2023-08-04 jrmu (test-eval '(or (begin (set! x (+ x 1)) x)) 26)
670 665c255d 2023-08-04 jrmu '(cond ((assoc 'b '((a 1) (b 2))) => cadr)
671 665c255d 2023-08-04 jrmu (else false))
675 665c255d 2023-08-04 jrmu '(cond ((= 3 4) 'not-true)
676 665c255d 2023-08-04 jrmu ((= (* 2 4) 3) 'also-false)
677 665c255d 2023-08-04 jrmu ((map (lambda (x)
678 665c255d 2023-08-04 jrmu (* x (+ x 1)))
679 665c255d 2023-08-04 jrmu '(2 4 1 9))
681 665c255d 2023-08-04 jrmu (lambda (x)
682 665c255d 2023-08-04 jrmu (accumulate + 0 x)))
683 665c255d 2023-08-04 jrmu (else 'never-reach))
685 665c255d 2023-08-04 jrmu ;; '(6 20 2 90)
688 665c255d 2023-08-04 jrmu ;; procedure definition and application
690 665c255d 2023-08-04 jrmu '(define (factorial n)
691 665c255d 2023-08-04 jrmu (if (= n 0)
693 665c255d 2023-08-04 jrmu (* n (factorial (- n 1))))))
694 665c255d 2023-08-04 jrmu (test-eval '(factorial 5) 120)
699 665c255d 2023-08-04 jrmu '(map (lambda (x)
700 665c255d 2023-08-04 jrmu (* x (+ x 1)))
701 665c255d 2023-08-04 jrmu '(2 1 4 2 8 3))
702 665c255d 2023-08-04 jrmu '(6 2 20 6 72 12))
703 665c255d 2023-08-04 jrmu ;; accumulate
706 665c255d 2023-08-04 jrmu '(accumulate + 0 '(1 2 3 4 5))
709 665c255d 2023-08-04 jrmu ;; make-let
711 665c255d 2023-08-04 jrmu (make-let '(x y) '(3 5) '((+ x y)))
718 665c255d 2023-08-04 jrmu '(let ((x 3))
722 665c255d 2023-08-04 jrmu '(let ((x 3)
727 665c255d 2023-08-04 jrmu '(let ((x 3)
729 665c255d 2023-08-04 jrmu (+ (let ((x (+ y 2))
733 665c255d 2023-08-04 jrmu (+ (* 4 3) 3 2))
735 665c255d 2023-08-04 jrmu '(let ((x 6)
736 665c255d 2023-08-04 jrmu (y (let ((x 2))
738 665c255d 2023-08-04 jrmu (z (let ((a (* 3 2)))
747 665c255d 2023-08-04 jrmu '(let* ((x 3)
748 665c255d 2023-08-04 jrmu (y (+ x 2))
749 665c255d 2023-08-04 jrmu (z (+ x y 5)))
758 665c255d 2023-08-04 jrmu '(let* ((x 3))
759 665c255d 2023-08-04 jrmu (let* ((y 5))
764 665c255d 2023-08-04 jrmu '(let* ((x 3)
765 665c255d 2023-08-04 jrmu (y (+ x 1)))
766 665c255d 2023-08-04 jrmu (+ (let* ((x (+ y 2))
770 665c255d 2023-08-04 jrmu (+ (* 6 6) 3 4))
772 665c255d 2023-08-04 jrmu '(let* ((x 6)
773 665c255d 2023-08-04 jrmu (y (let* ((x 2)
774 665c255d 2023-08-04 jrmu (a (let* ((x (* 3 x)))
777 665c255d 2023-08-04 jrmu (z (+ x y)))
781 665c255d 2023-08-04 jrmu ;; named-let
784 665c255d 2023-08-04 jrmu '(let eight ()
790 665c255d 2023-08-04 jrmu '(let loop ((count 0))
791 665c255d 2023-08-04 jrmu (if (= 100 count)
793 665c255d 2023-08-04 jrmu (loop (+ count 1))))
796 665c255d 2023-08-04 jrmu '(define (prime? x)
797 665c255d 2023-08-04 jrmu (let prime-iter ((i 2))
798 665c255d 2023-08-04 jrmu (cond ((> (* i i) x) true)
799 665c255d 2023-08-04 jrmu ((= (remainder x i) 0) false)
800 665c255d 2023-08-04 jrmu (else (prime-iter (+ i 1)))))))
802 665c255d 2023-08-04 jrmu '(let primes ((x 2)
804 665c255d 2023-08-04 jrmu (cond ((= n 0) '())
805 665c255d 2023-08-04 jrmu ((prime? x)
807 665c255d 2023-08-04 jrmu (primes (+ x 1) (- n 1))))
808 665c255d 2023-08-04 jrmu (else (primes (+ x 1) n))))
809 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))
812 665c255d 2023-08-04 jrmu '(define (fib n)
813 665c255d 2023-08-04 jrmu (let fib-iter ((a 1)
816 665c255d 2023-08-04 jrmu (if (= count 0)
818 665c255d 2023-08-04 jrmu (fib-iter (+ a b) a (- count 1))))))
819 665c255d 2023-08-04 jrmu (test-eval '(fib 19) 4181)
823 665c255d 2023-08-04 jrmu '(let ((y 0))
824 665c255d 2023-08-04 jrmu (do ((x 0 (+ x 1)))
825 665c255d 2023-08-04 jrmu ((= x 5) y)
826 665c255d 2023-08-04 jrmu (set! y (+ y 1))))
837 665c255d 2023-08-04 jrmu '(let ((y 0))
839 665c255d 2023-08-04 jrmu ((= y 5) y)
840 665c255d 2023-08-04 jrmu (set! y (+ y 1))))
844 665c255d 2023-08-04 jrmu '(do ((y '(1 2 3 4)))
845 665c255d 2023-08-04 jrmu ((null? y))
846 665c255d 2023-08-04 jrmu (set! y (cdr y)))
849 665c255d 2023-08-04 jrmu '(let ((y 0))
850 665c255d 2023-08-04 jrmu (do ((x 0 (+ x 1)))
851 665c255d 2023-08-04 jrmu ((= x 5) y)
852 665c255d 2023-08-04 jrmu (set! y (+ y 1))))
855 665c255d 2023-08-04 jrmu '(let ((x '(1 3 5 7 9)))
856 665c255d 2023-08-04 jrmu (do ((x x (cdr x))
857 665c255d 2023-08-04 jrmu (sum 0 (+ sum (car x))))
858 665c255d 2023-08-04 jrmu ((null? x) sum)))
861 665c255d 2023-08-04 jrmu '(let ((z '()))
862 665c255d 2023-08-04 jrmu (do ((x '(1 2 3 4) (cdr x))
863 665c255d 2023-08-04 jrmu (y '(1 2 3 4 5 6 7 8) (cddr y)))
864 665c255d 2023-08-04 jrmu ((null? x) y x z)
865 665c255d 2023-08-04 jrmu (set! z (cons (car x) z))))
866 665c255d 2023-08-04 jrmu '(4 3 2 1))
870 665c255d 2023-08-04 jrmu ;; make-unbound!
871 665c255d 2023-08-04 jrmu ;; broken now due to scan-out-defines
873 665c255d 2023-08-04 jrmu ;; (test-eval
874 665c255d 2023-08-04 jrmu ;; '(let ((x 3))
875 665c255d 2023-08-04 jrmu ;; (let ((x 5))
876 665c255d 2023-08-04 jrmu ;; (make-unbound! x)
877 665c255d 2023-08-04 jrmu ;; (* x x)))
880 665c255d 2023-08-04 jrmu ;; (test-eval
881 665c255d 2023-08-04 jrmu ;; '(let ((x 3))
882 665c255d 2023-08-04 jrmu ;; (let ((x 5))
883 665c255d 2023-08-04 jrmu ;; (define y x)
884 665c255d 2023-08-04 jrmu ;; (make-unbound! x)
885 665c255d 2023-08-04 jrmu ;; (* y x)))
888 665c255d 2023-08-04 jrmu ;; (test-eval
889 665c255d 2023-08-04 jrmu ;; '(let ((y -1) (x 3))
890 665c255d 2023-08-04 jrmu ;; (let ((y 0.5) (x 5))
891 665c255d 2023-08-04 jrmu ;; (define a x)
892 665c255d 2023-08-04 jrmu ;; (define b y)
893 665c255d 2023-08-04 jrmu ;; (make-unbound! x)
894 665c255d 2023-08-04 jrmu ;; (make-unbound! y)
895 665c255d 2023-08-04 jrmu ;; (* a b x y)))
896 665c255d 2023-08-04 jrmu ;; (* 5 3 -1 0.5))
898 665c255d 2023-08-04 jrmu ;; (test-eval
899 665c255d 2023-08-04 jrmu ;; '(let ((x 3) (y 4))
900 665c255d 2023-08-04 jrmu ;; (let ((x 5))
901 665c255d 2023-08-04 jrmu ;; (make-unbound! x)
902 665c255d 2023-08-04 jrmu ;; (+ x 4)))
905 665c255d 2023-08-04 jrmu ;; (test-eval
906 665c255d 2023-08-04 jrmu ;; '(let ((a 1) (b 2) (c 3) (d 4))
907 665c255d 2023-08-04 jrmu ;; (make-unbound! b)
908 665c255d 2023-08-04 jrmu ;; (+ a c d))
909 665c255d 2023-08-04 jrmu ;; (+ 1 3 4))
911 665c255d 2023-08-04 jrmu ;; (test-eval
912 665c255d 2023-08-04 jrmu ;; '(let ((x 4) (y 5))
913 665c255d 2023-08-04 jrmu ;; (let ((a 1) (b 2) (c 3))
914 665c255d 2023-08-04 jrmu ;; (let ((x (+ a b)) (y (+ c a)))
915 665c255d 2023-08-04 jrmu ;; (make-unbound! x)
916 665c255d 2023-08-04 jrmu ;; (let ((a x) (b (+ x y)))
917 665c255d 2023-08-04 jrmu ;; (define z b)
918 665c255d 2023-08-04 jrmu ;; (make-unbound! b)
919 665c255d 2023-08-04 jrmu ;; (* (+ a z)
920 665c255d 2023-08-04 jrmu ;; (+ a b y))))))
921 665c255d 2023-08-04 jrmu ;; (* (+ 4 8)
922 665c255d 2023-08-04 jrmu ;; (+ 4 2 4)))
924 665c255d 2023-08-04 jrmu ;; x 3 -- y 4
925 665c255d 2023-08-04 jrmu ;; x 4 -- y 4
926 665c255d 2023-08-04 jrmu ;; a 4 -- b 4
927 665c255d 2023-08-04 jrmu ;; a 4 -- b 2
929 665c255d 2023-08-04 jrmu ;; scan-out-defines
932 665c255d 2023-08-04 jrmu '(define (f x)
933 665c255d 2023-08-04 jrmu (define (even? n)
934 665c255d 2023-08-04 jrmu (if (= n 0)
936 665c255d 2023-08-04 jrmu (odd? (- n 1))))
937 665c255d 2023-08-04 jrmu (define (odd? n)
938 665c255d 2023-08-04 jrmu (if (= n 0)
940 665c255d 2023-08-04 jrmu (even? (- n 1))))
941 665c255d 2023-08-04 jrmu (even? x)))
942 665c255d 2023-08-04 jrmu (test-eval '(f 5) false)
943 665c255d 2023-08-04 jrmu (test-eval '(f 10) true)
946 665c255d 2023-08-04 jrmu ;; '(let ((x 5))
947 665c255d 2023-08-04 jrmu ;; (define y x)
948 665c255d 2023-08-04 jrmu ;; (define x 3)
949 665c255d 2023-08-04 jrmu ;; (+ x y)))
950 665c255d 2023-08-04 jrmu ;; signal an error because x is undefined if variables are scanned out
955 665c255d 2023-08-04 jrmu '(define (f x)
956 665c255d 2023-08-04 jrmu (letrec ((even?
957 665c255d 2023-08-04 jrmu (lambda (n)
958 665c255d 2023-08-04 jrmu (if (= n 0)
960 665c255d 2023-08-04 jrmu (odd? (- n 1)))))
962 665c255d 2023-08-04 jrmu (lambda (n)
963 665c255d 2023-08-04 jrmu (if (= n 0)
965 665c255d 2023-08-04 jrmu (even? (- n 1))))))
966 665c255d 2023-08-04 jrmu (even? x))))
967 665c255d 2023-08-04 jrmu (test-eval '(f 11) false)
968 665c255d 2023-08-04 jrmu (test-eval '(f 16) true)
971 665c255d 2023-08-04 jrmu '(letrec ((fact
972 665c255d 2023-08-04 jrmu (lambda (n)
973 665c255d 2023-08-04 jrmu (if (= n 1)
975 665c255d 2023-08-04 jrmu (* n (fact (- n 1)))))))
