blob: cdc84f9b5c22180ccc6b5289bc9f13f3708ec5b0 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
|
#lang racket
; Do list.rkt dodajemy procedury
;
; Miejsca, ktore sie zmienily oznaczone sa przez !!!
(provide parse eval)
; --------- ;
; Wyrazenia ;
; --------- ;
(struct const (val) #:transparent)
(struct binop (op l r) #:transparent)
(struct var-expr (id) #:transparent)
(struct let-expr (id e1 e2) #:transparent)
(struct if-expr (eb et ef) #:transparent)
(struct cons-expr (e1 e2) #:transparent)
(struct car-expr (e) #:transparent)
(struct cdr-expr (e) #:transparent)
(struct null-expr () #:transparent)
(struct null?-expr (e) #:transparent)
(struct app (f e) #:transparent) ; <------------------ !!!
(struct lam (id e) #:transparent) ; <------------------ !!!
(define (expr? e)
(match e
[(const n) (or (number? n) (boolean? n))]
[(binop op l r) (and (symbol? op) (expr? l) (expr? r))]
[(var-expr x) (symbol? x)]
[(let-expr x e1 e2)
(and (symbol? x) (expr? e1) (expr? e2))]
[(if-expr eb et ef)
(and (expr? eb) (expr? et) (expr? ef))]
[(cons-expr e1 e2) (and (expr? e1) (expr? e2))]
[(car-expr e) (expr? e)]
[(cdr-expr e) (expr? e)]
[(null-expr) true]
[(null?-expr e) (expr? e)]
[(app f e) (and (expr? f) (expr? e))] ; <--------------------- !!!
[(lam id e) (and (symbol? id) (expr? e))] ; <----------------- !!!
[_ false]))
(define (parse q)
(cond
[(number? q) (const q)]
[(eq? q 'true) (const true)]
[(eq? q 'false) (const false)]
[(eq? q 'null) (null-expr)]
[(symbol? q) (var-expr q)]
[(and (list? q) (eq? (length q) 2) (eq? (first q) 'null?))
(null?-expr (parse (second q)))]
[(and (list? q) (eq? (length q) 3) (eq? (first q) 'cons))
(cons-expr (parse (second q))
(parse (third q)))]
[(and (list? q) (eq? (length q) 2) (eq? (first q) 'car))
(car-expr (parse (second q)))]
[(and (list? q) (eq? (length q) 2) (eq? (first q) 'cdr))
(cdr-expr (parse (second q)))]
[(and (list? q) (eq? (length q) 3) (eq? (first q) 'let))
(let-expr (first (second q))
(parse (second (second q)))
(parse (third q)))]
[(and (list? q) (eq? (length q) 4) (eq? (first q) 'if))
(if-expr (parse (second q))
(parse (third q))
(parse (fourth q)))]
[(and (list? q) (eq? (length q) 3) (eq? (first q) 'lambda)) ; <!!!
(parse-lam (second q) (third q))]
[(and (list? q) (pair? q) (not (op->proc (car q)))) ; <------- !!!
(parse-app q)]
[(and (list? q) (eq? (length q) 3) (symbol? (first q)))
(binop (first q)
(parse (second q))
(parse (third q)))]))
(define (parse-app q) ; <----------------------------------------- !!!
(define (parse-app-accum q acc)
(cond [(= 1 (length q)) (app acc (parse (car q)))]
[else (parse-app-accum (cdr q) (app acc (parse (car q))))]))
(parse-app-accum (cdr q) (parse (car q))))
(define (parse-lam pat e) ; <------------------------------------- !!!
(cond [(= 1 (length pat))
(lam (car pat) (parse e))]
[else
(lam (car pat) (parse-lam (cdr pat) e))]))
; ---------- ;
; Srodowiska ;
; ---------- ;
(struct environ (xs) #:transparent)
(define env-empty (environ null))
(define (env-add x v env)
(environ (cons (cons x v) (environ-xs env))))
(define (env-lookup x env)
(define (assoc-lookup xs)
(cond [(null? xs) (error "Unknown identifier" x)]
[(eq? x (car (car xs))) (cdr (car xs))]
[else (assoc-lookup (cdr xs))]))
(assoc-lookup (environ-xs env)))
; --------- ;
; Ewaluacja ;
; --------- ;
(struct clo (id e env) #:transparent) ; <------------------------- !!!
(struct odr (e env) #:transparent)
(define (value? v)
(or (number? v)
(boolean? v)
(and (pair? v) (value? (car v)) (value? (cdr v)))
(null? v)
(clo? v))) ; <---------------------------------------------- !!!
(define (op->proc op)
(match op ['+ +] ['- -] ['* *] ['/ /] ['% modulo]
['= =] ['> >] ['>= >=] ['< <] ['<= <=]
['and (lambda (x y) (and x y))]
['or (lambda (x y) (or x y))]
[_ false])) ; <--------------------------------------- !!!
(define (eval-env e env)
(match e
[(const n) n]
[(binop op l r) ((op->proc op) (eval-env l env)
(eval-env r env))]
[(let-expr x e1 e2)
(eval-env e2 (env-add x (eval-env e1 env) env))]
[(var-expr x) (match (env-lookup x env)
[(odr e env) (eval-env e env)]
[f f])]
[(if-expr eb et ef) (if (eval-env eb env)
(eval-env et env)
(eval-env ef env))]
[(cons-expr e1 e2) (cons (odr e1 env)
(odr e2 env))]
[(car-expr e) (let ([p (eval-env e env)])
(match (car p)
[(odr e env) (eval-env e env)]))]
[(cdr-expr e) (let ([p (eval-env e env)])
(match (cdr p)
[(odr e env) (eval-env e env)]))]
[(null-expr) null]
[(null?-expr e) (null? (eval-env e env))]
[(lam x e) (clo x e env)] ; <--------------------------------- !!!
[(app f e) ; <------------------------------------------------ !!!
(let ([vf (eval-env f env)]
[ve (odr e env)])
(match vf [(clo x body fun-env)
(eval-env body (env-add x ve fun-env))]))]))
(define (eval e) (eval-env e env-empty))
(define program
'(let [twice (lambda (f x) (f (f x)))]
(let [inc (lambda (x) (+ 1 x))]
(twice twice twice twice inc 1))))
;;; Testy wspólnie z Karolem Ochmanem
(define (test-eval program) (eval (parse program)))
(define program1
'((lambda (x) (+ 3 3)) (/ 5 0)))
(define program2
'(let [if-fun (lambda (b t e) (if b t e))]
(if-fun true 4 (/ 5 0))))
(define program3
'(car (cdr (cons 1 (cons 2 (cons 3 (cons 4 null)))))))
(define program4
'(car (cons (+ 3 4) (/ 5 0))))
(define program5
'(cons (+ 5 6) (- 4 3)))
(define program6
'(car (cdr (cdr (car (cons (cons (/ 0 0) (cons (/ 0 0) (cons 1 (/ 0 0)))) (cdr (cons (/ 0 0) null))))))))
;;; (test-eval program)
;;; (test-eval program1)
;;; (test-eval program2)
;;; (test-eval program3)
;;; (test-eval program4)
;;; (test-eval program5)
;;; (test-eval program6)
|
