From 9477dbe667f250ecd23f8fc0d56b942191526421 Mon Sep 17 00:00:00 2001 From: Franciszek Malinka Date: Thu, 25 Feb 2021 14:42:55 +0100 Subject: Stare semestry, niepoukladane --- Semestr 2/racket/l8z15/solution.rkt | 182 ++++++++++++++++++++++++++++++++++++ 1 file changed, 182 insertions(+) create mode 100644 Semestr 2/racket/l8z15/solution.rkt (limited to 'Semestr 2/racket/l8z15/solution.rkt') diff --git a/Semestr 2/racket/l8z15/solution.rkt b/Semestr 2/racket/l8z15/solution.rkt new file mode 100644 index 0000000..54b6cd3 --- /dev/null +++ b/Semestr 2/racket/l8z15/solution.rkt @@ -0,0 +1,182 @@ +#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)) ; 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)) + + +;;; 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) \ No newline at end of file -- cgit v1.2.3