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a4.rkt
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a4.rkt
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;Yu Gao
#lang racket
(define lex
(lambda (expr ls)
(match expr
(`,y #:when (symbol? y) `(var ,
(if (boolean? (assv expr ls))
0
(cadr (assv expr ls)))))
(`,n #:when (number? n) `(const ,n))
;;boolean depends in specific condition or it will fail when referring env (`,b #:when (boolean? b) 0)
(`(lambda (,x) ,body) `(lambda ,(lex body (if (boolean? (assv x ls))
(cons (cons x (cons 0 '())) (map (lambda (lis) (list (car lis) (add1 (cadr lis)))) ls))
(cons (cons x (cons 0 '())) ((remove (assv x ls) ls)))))))
(`(,rator ,rand) (list (lex rator ls) (lex rand ls)))
(`(if ,e1 ,e2 ,e3) `(if ,(lex e1 ls)
,(lex e2 ls)
,(lex e3 ls)))
(`(zero? ,e) `(zero? ,(lex e ls)))
(`(sub1 ,e) `(sub1 ,(lex e ls)))
(`(* ,e1 ,e2) `(* ,(lex e1 ls) ,(lex e2 ls)))
(`(let [(,x ,val)] ,body)
`(let ,(lex val ls) ,(lex body ls)))
(`(,rator ,rand) `(,(lex rator ls) ,(lex rand ls))))))
;;''value-of-fn'' should use a functional representation of closures.
(define empty-env
(lambda ()
'()))
(define extend-env
(lambda (x a env)
`((,x . ,a) . ,env)))
(define apply-env
(lambda (env y)
(cond
[(assq y env) (cdr (assq y env) )]
[else (error 'env "Unbounded variables ~s" y)])))
(define closure-fn
(lambda (x body env)
(lambda (arg)
(value-of-fn body (extend-env x arg env)))))
(define apply-closure-fn
(lambda (a arg)
(a arg)))
(define value-of-fn
(lambda (exp env)
(match exp
[`,x #:when (symbol? x) (apply-env env exp)]
[`,n #:when (number? n) n]
[`,b #:when (boolean? b) b]
[`(lambda (,x) ,body) (closure-fn x body env)]
[`(zero? ,e) (zero? (value-of-fn e env))]
[`(* ,e1 ,e2) (* (value-of-fn e1 env) (value-of-fn e2 env))]
[`(sub1 ,e) (sub1 (value-of-fn e env))]
[`(let ([,x ,y]) ,body) (value-of-fn body (extend-env x (value-of-fn y env) env))]
[`(if ,e1 ,e2 ,e3) (if (value-of-fn e1 env)
(value-of-fn e2 env)
(value-of-fn e3 env))]
[`(,rator ,rand) (apply-closure-fn (value-of-fn rator env) (value-of-fn rand env))])))
;;''value-of-ds'' should use a data-structural representation of closures.
(define closure-ds
(lambda (x body env)
`(closure ,x ,body ,env)))
(define apply-closure-ds
(lambda (closure a)
(match closure
[`(closure ,x ,body ,env) (value-of-ds body (extend-env x a env))])))
(define value-of-ds
(lambda (exp env)
(match exp
[`,x #:when (symbol? x) (apply-env env exp)]
[`,n #:when (number? n) n]
[`(lambda (,x) ,body) (closure-ds x body env)]
[`(zero? ,e) (zero? (value-of-ds e env))]
[`(* ,e1 ,e2) (* (value-of-ds e1 env) (value-of-ds e2 env))]
[`(sub1 ,e) (sub1 (value-of-ds e env))]
[`(let ([,x ,y]) ,body) (value-of-ds body (extend-env x (value-of-ds y env) env))]
[`(if ,e1 ,e2 ,e3) (if (value-of-ds e1 env)
(value-of-ds e2 env)
(value-of-ds e3 env))]
[`(,rator ,rand) (apply-closure-ds (value-of-ds rator env) (value-of-ds rand env))])))
;;3
(define closure-scopes
(case-lambda
[(x body env) `(closure ,x ,body ,env)]
[(x body) `(closure ,x ,body)]))
(define apply-closure-scopes
(lambda (closure a env)
(match closure
[`(closure ,x ,body ,env) (value-of-scopes body (extend-env x a env))]
[`(closure ,x ,body) (value-of-scopes body (extend-env x a env))])))
(define value-of-scopes
(lambda (exp env)
(match exp
[`,x #:when (symbol? x) (apply-env env exp)]
[`,n #:when (number? n) n]
[`,b #:when (boolean? b) b]
[`(null? ,e) (equal? (value-of-scopes e env) '())]
[`(cons ,e1 ,e2) (cons (value-of-scopes e1 env) (value-of-scopes e2 env))]
[`(car ,e) (car (value-of-scopes e env))]
[`(cdr ,e) (cdr (value-of-scopes e env))]
[`(let ((,x ,y)) ,body) (let ((a (value-of-scopes y env))) (value-of-scopes body (extend-env x a env)))]
[`(lambda (,x) ,body) (closure-scopes x body env)]
[`(d-lambda (,x) ,body) (closure-scopes x body)]
[`(quote()) '()]
[`(if ,e1 ,e2 ,e3) (if (value-of-scopes e1 env)
(value-of-scopes e2 env)
(value-of-scopes e3 env))]
[`(,rator ,rand) (apply-closure-scopes (value-of-scopes rator env)
(value-of-scopes rand env)
env)])))
;;value-of-dynamics
(define value-of-dynamic
(lambda (expr env)
(match expr
[`,x #:when (symbol? x) (apply-env env x)]
[`,x #:when (number? x) x]
[`,b #:when (boolean? b) b]
[`(lambda (,x) ,body) `(lambda (,x) ,body)]
[`(let ((,a ,b)) ,body)
(let ((c (value-of-dynamic b env)))
(value-of-dynamic body (extend-env a c env)))]
[`(if ,e1 ,e2 ,e3)
(if (value-of-dynamic e1 env)
(value-of-dynamic e2 env)
(value-of-dynamic e3 env))]
[`(* ,e1 ,e2) (* (value-of-dynamic e1 env) (value-of-dynamic e2 env))]
[`(+ ,e1 ,e2) (+ (value-of-dynamic e1 env) (value-of-dynamic e2 env))]
[`(sub1 ,num) (sub1 (value-of-dynamic num env))]
[`(null? ,ls) (null? (value-of-dynamic ls env))]
[`(zero? ,num) (zero? (value-of-dynamic num env))]
[`(cons ,a ,b) (cons (value-of-dynamic a env) (value-of-dynamic b env))]
[`(car ,a) (car (value-of-dynamic a env))]
[`(cdr ,a) (cdr (value-of-dynamic a env))]
[`(quote ,v) v]
[`(,rator ,rand)
;; (match (value-of-dynamic rator env)
;; [`(lambda (,x) ,body)
;; (value-of-dynamic body (extend-env x (value-of-dynamic rand env) env))])]
(match-let ([`(lambda (,x) ,body) (value-of-dynamic rator env)])
(value-of-dynamic body (extend-env x (value-of-dynamic rand env) env)))])))