(and (list? t) (eq? (car t) 'abs)))
(define (tvar? t)
- (and (not (list? t)) (not (concrete? t)) (symbol? t)))
+ (and (not (list? t))
+ (not (concrete? t))
+ (symbol? t)))
(define (concrete? t)
- (case t
- ('int #t)
- ('bool #t)
- ('void #t)
- (else #f)))
+ (and (symbol? t)
+ (char-upper-case? (string-ref (symbol->string t) 0))))
(define (pretty-type t)
(cond ((abs? t)
(define (builtin-type x)
(case x
- ('+ '(abs int (abs int int)))
- ('- '(abs int (abs int int)))
- ('* '(abs int (abs int int)))
- ('! '(abs bool bool))
- ('= '(abs int (abs int bool)))
- ('bool->int '(abs bool int))
- ('print '(abs string void))
- (else #f)))
-
-(define (check env x)
- ;; (display "check: ")
- ;; (display x)
- ;; (display "\n\t")
- ;; (display env)
- ;; (newline)
- (let
- ((res
- (case (ast-type x)
- ('int-literal (list '() 'int))
- ('bool-literal (list '() 'bool))
- ('string-literal (list '() 'string))
- ('builtin (list '() (builtin-type x)))
-
- ('if
- (let* ((cond-type-res (check env (cadr x)))
- (then-type-res (check env (caddr x)))
- (else-type-res (check env (cadddr x)))
- (then-eq-else-cs (~ (cadr then-type-res)
- (cadr else-type-res)))
- (cs (constraint-merge
- (car then-type-res)
- (constraint-merge (car else-type-res)
- then-eq-else-cs)))
- (return-type (substitute cs (cadr then-type-res))))
- (when (not (eqv? (cadr cond-type-res) 'bool))
- (error #f "if condition isn't bool"))
- (list cs return-type)))
-
- ('var (list '() (env-lookup env x)))
- ('let
+ ('+ '(abs Int (abs Int Int)))
+ ('- '(abs Int (abs Int Int)))
+ ('* '(abs Int (abs Int Int)))
+ ('! '(abs Bool Bool))
+ ('= '(abs Int (abs Int Bool)))
+ ('bool->int '(abs Bool Int))
+ ('print '(abs String Void))
+ (else (error #f "Couldn't find type for builtin" x))))
+
+(define (check-let env x)
; takes in the current environment and a scc
; returns new environment with scc's types added in
(let* ([components (reverse (sccs (graph (let-bindings x))))]
[new-env (fold-left process-component env components)])
(check new-env (last (let-body x)))))
+(define (check env x)
+ (display "check: ")
+ (display x)
+ (display "\n\t")
+ (display env)
+ (newline)
+ (let
+ ((res
+ (case (ast-type x)
+ ('int-literal (list '() 'Int))
+ ('bool-literal (list '() 'Bool))
+ ('string-literal (list '() 'String))
+ ('builtin (list '() (builtin-type x)))
+
+ ('if
+ (let* ((cond-type-res (check env (cadr x)))
+ (then-type-res (check env (caddr x)))
+ (else-type-res (check env (cadddr x)))
+ (then-eq-else-cs (~ (cadr then-type-res)
+ (cadr else-type-res)))
+ (cs (constraint-merge
+ (car then-type-res)
+ (constraint-merge (~ (cadr cond-type-res) 'Bool)
+ (constraint-merge (car else-type-res)
+ then-eq-else-cs))))
+ (return-type (substitute cs (cadr then-type-res))))
+ (list cs return-type)))
+
+ ('var (list '() (env-lookup env x)))
+ ('let (check-let env x))
+
+
('lambda
(let* [(new-env (env-insert env (lambda-arg x) (fresh-tvar)))
(let ((return-type (substitute cs (caddr resolved-func-type))))
(list cs return-type))
(error #f "not a function")))))))
- ;; (display "result of ")
- ;; (display x)
- ;; (display ":\n\t")
- ;; (display (pretty-type (cadr res)))
- ;; (display "\n\t[")
- ;; (display (pretty-constraints (car res)))
- ;; (display "]\n")
+ (display "result of ")
+ (display x)
+ (display ":\n\t")
+ (display (pretty-type (cadr res)))
+ (display "\n\t[")
+ (display (pretty-constraints (car res)))
+ (display "]\n")
res))
; we typecheck the lambda calculus only (only single arg lambdas)
(define (typecheck prog)
- (cadr (check '() (normalize prog))))
+ (define (constructor-type t ctr)
+ (fold-left (lambda (acc x) `(abs ,x ,acc)) t (cdr ctr)))
+ (define (constructors data-def)
+ (let ([type-name (cadr data-def)]
+ [ctrs (cddr data-def)])
+ (fold-left (lambda (acc ctr)
+ (cons (cons (car ctr) (constructor-type type-name ctr))
+ acc))
+ '()
+ ctrs)))
+ (let ([init-env (flat-map constructors (program-datas prog))])
+ (display init-env)
+ (cadr (check init-env (normalize (program-body prog))))))
; returns a list of constraints
(define (~ a b)
;; ; a1 -> a2 ~ a3 -> a4;
-;; ; a1 -> a2 !~ bool -> bool
+;; ; a1 -> a2 !~ Bool -> Bool
;; ; basically can the tvars be renamed
(define (types-equal? x y)
(let ([cs (unify? x y)])