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#lang typed/racket
; Do let-env.rkt dodajemy wartosci boolowskie
;
; Miejsca, ktore sie zmienily oznaczone sa przez !!!
; --------- ;
; Wyrazenia ;
; --------- ;
(provide parse typecheck)
(define-type Value (U Boolean Real))
(define-type Expr (U const binop var-expr let-expr if-expr))
(define-type ArithSymbol (U '+ '- '* '/))
(define-type LogicSymbol (U 'and 'or))
(define-type CompSymbol (U '< '= '> '<= '>=))
(define-type BinomSymbol (U ArithSymbol LogicSymbol CompSymbol))
(define-type Binop-list (List BinomSymbol Any Any))
(define-type Let-list (List 'let (List Symbol Any) Any))
(define-type If-list (List 'if Any Any Any))
(define-predicate Binop-list? Binop-list)
(define-predicate Let-list? Let-list)
(define-predicate If-list? If-list)
(struct const ([val : Value]) #:transparent)
(struct binop ([op : BinomSymbol] [l : Expr] [r : Expr]) #:transparent)
(struct var-expr ([id : Symbol]) #:transparent)
(struct let-expr ([id : Symbol] [e1 : Expr] [e2 : Expr]) #:transparent)
(struct if-expr ([eb : Expr] [et : Expr] [ef : Expr]) #:transparent)
(define-predicate Value? Value)
(define-predicate Expr? Expr)
(define-predicate BinomSymbol? BinomSymbol)
(define-predicate ArithSymbol? ArithSymbol)
(define-predicate LogicSymbol? LogicSymbol)
(define-predicate CompSymbol? CompSymbol)
(define-predicate BinomValue? BinomValue)
(: parse (-> Any Expr))
(define (parse q)
(cond
[(real? q) (const q)]
[(eq? q 'true) (const true)] ; <---------------------------- !!!
[(eq? q 'false) (const false)] ; <---------------------------- !!!
[(symbol? q) (var-expr q)]
[(Let-list? q)
(let-expr (first (second q))
(parse (second (second q)))
(parse (third q)))]
[(If-list? q) ; <--- !!!
(if-expr (parse (second q))
(parse (third q))
(parse (fourth q)))]
[(Binop-list? q)
(binop (first q)
(parse (second q))
(parse (third q)))]
[else (error "Blad parsowania" q)]))
(define (test-parse) (parse '(let [x (+ 2 2)] (+ x 1))))
; ---------- ;
; Srodowiska ;
; ---------- ;
(define-type EType ( U 'real 'boolean ) )
(define-type Env (Listof (Pairof Symbol EType)))
(define-predicate Env? Env)
(struct environ ([xs : Env]))
(: env-empty environ)
(define env-empty (environ null))
(: env-add (-> Symbol EType environ environ))
(define (env-add x v env)
(environ (cons (cons x v) (environ-xs env))))
(: env-lookup (-> Symbol environ (U EType #f)))
(define (env-lookup x env)
(: assoc-lookup (-> Env EType))
(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)))
(: typecheck (-> Expr (U EType #f)))
(define (typecheck q)
(: give (-> Expr environ (U EType #f)))
(define (give q envi)
(cond
[(const? q) (if (boolean? (const-val q)) 'boolean 'real)]
[(var-expr? q) (env-lookup (var-expr-id q) envi)]
[(let-expr? q)
(let ([p (give (let-expr-e1 q) envi)]) (if (false? p) #f (give (let-expr-e2 q) (env-add (let-expr-id q) p envi))))]
[(binop? q)
(cond
([ArithSymbol? (binop-op q)] (if (and (eq? 'real (give (binop-l q) envi)) (eq? 'real (give (binop-r q) envi))) 'real #f))
([LogicSymbol? (binop-op q)] (if (and (eq? 'boolean (give (binop-l q) envi)) (eq? 'boolean (give (binop-r q) envi))) 'boolean #f))
([CompSymbol? (binop-op q)] (if (and (eq? 'real (give (binop-l q) envi)) (eq? 'real (give (binop-r q) envi))) 'boolean #f))
[else #f])]
[(if-expr? q)
(if (and (eq? 'real (if-expr-eb q))
(eq? (give (if-expr-et q) envi) (give (if-expr-ef q) envi)))
(give (if-expr-et q) envi)
#f)]
[else #f]))
(give q env-empty))
(define program2
'(if true
(let [x 5] (+ 5 false))
(/ 2 2)))
(define program3
'(let [x (+ 2 3)]
(let [y (< 2 3)]
(+ x y))))
(define program4
'(let [x (and true true)] x))
(define wtf
'(and true true))
(typecheck (parse program2))
(typecheck (parse program3))
(typecheck (parse program4))
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