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type-check-poly.rkt
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#lang racket
(require "utilities.rkt")
(require "type-check-Llambda.rkt")
(provide type-check-poly type-check-poly-class)
(define type-check-poly-class
(class type-check-Llambda-class
(super-new)
(inherit check-type-equal?)
;; This is slow. Should instead convert to de Bruijn
;; or add a parameter for the environment. -Jeremy
(define/override (type-equal? t1 t2)
(match* (t1 t2)
[(`(All ,xs ,T1) `(All ,ys ,T2))
(define env (map cons xs ys))
(type-equal? (subst-type env T1) T2)]
[(other wise)
(super type-equal? t1 t2)]))
(define/public (match-types env pat1 t2)
(verbose 'type-check "match-types" env pat1 t2)
(define result
(match* (pat1 t2)
[('Integer 'Integer) env]
[('Boolean 'Boolean) env]
[('Void 'Void) env]
[('Any 'Any) env]
[(`(Vector ,ts1 ...) `(Vector ,ts2 ...))
(for/fold ([env^ env]) ([pat1 ts1] [t2 ts2])
(match-types env^ pat1 t2))]
[(`(,ts1 ... -> ,rt1) `(,ts2 ... -> ,rt2))
(define env^ (match-types env rt1 rt2))
(for/fold ([env^^ env^]) ([pat1 ts1] [t2 ts2])
(match-types env^^ pat1 t2))]
[(`(All ,xs1 ,t1) `(All ,xs2 ,t2))
(define env^ (append (map cons xs1 xs2) env))
(match-types env^ t1 t2)]
[((? symbol? x) t)
(match (dict-ref env x (lambda () #f))
[#f (error 'type-check "undefined type variable ~a" x)]
['Type (cons (cons x t) env)]
[t^ (check-type-equal? t t^ 'matching) env])]
[(other wise) (error 'type-check "mismatch ~a != a" pat1 t2)]))
(copious 'match-types "done" pat1 t2 result)
result)
(define/public (subst-type env pat1)
(verbose 'type-check "subst" env pat1)
(match pat1
['Integer 'Integer]
['Boolean 'Boolean]
['Void 'Void]
['Any 'Any]
[`(Vector ,ts ...)
`(Vector ,@(for/list ([t ts]) (subst-type env t)))]
[`(,ts ... -> ,rt)
`(,@(for/list ([t ts]) (subst-type env t)) -> ,(subst-type env rt))]
[`(All ,xs ,t)
`(All ,xs ,(subst-type (append (map cons xs xs) env) t))]
[(? symbol? x) (dict-ref env x)]
[else (error 'type-check "expected a type not ~a" pat1)]))
(define/override (fun-def-type d)
(match d
[(Def f (list `[,xs : ,ps] ...) rt info body) `(,@ps -> ,rt)]
[(Poly ts (Def f (list `[,xs : ,ps] ...) rt info body))
`(All ,ts (,@ps -> ,rt))]
[else (error 'fun-def-type "expected function definition, not ~a" d)]))
(define/public (def-name d)
(match d
[(Def f params rt info body) f]
[(Poly ts (Def f params rt info body)) f]))
(define/public ((check-well-formed env) ty)
(match ty
['Integer (void)]
['Boolean (void)]
['Void (void)]
['Any (void)]
[(? symbol? a)
(match (dict-ref env a (lambda () #f))
['Type (void)]
[else (error 'type-check "undefined type variable ~a" a)])]
[`(Vector ,ts ...)
(for ([t ts]) ((check-well-formed env) t))]
[`(,ts ... -> ,t)
(for ([t ts]) ((check-well-formed env) t))
((check-well-formed env) t)]
[`(All ,xs ,t)
(define env^ (append (for/list ([x xs]) (cons x 'Type)) env))
((check-well-formed env^) t)]
[else (error 'type-check "unrecognized type ~a" ty)]))
(define/public (combine-decls-defs ds)
(match ds
['() '()]
[`(,(Decl name type) . (,(Def f params _ info body) . ,ds^))
(unless (equal? name f)
(error 'type-check "name mismatch, ~a != ~a" name f))
(match type
[`(All ,xs (,ps ... -> ,rt))
(define params^ (for/list ([x params] [T ps]) `[,x : ,T]))
(cons (Poly xs (Def name params^ rt info body))
(combine-decls-defs ds^))]
[`(,ps ... -> ,rt)
(define params^ (for/list ([x params] [T ps]) `[,x : ,T]))
(cons (Def name params^ rt info body) (combine-decls-defs ds^))]
[else (error 'type-check "expected a function type, not ~a" type)])]
[`(,(Def f params rt info body) . ,ds^)
(cons (Def f params rt info body) (combine-decls-defs ds^))]))
(define/override (type-check-apply env e1 es)
(define-values (e^ ty) ((type-check-exp env) e1))
(define-values (es^ ty*) (for/lists (es^ ty*) ([e (in-list es)])
((type-check-exp env) e)))
(match ty
[`(,ty^* ... -> ,rt)
(for ([arg-ty ty*] [param-ty ty^*])
(check-type-equal? arg-ty param-ty (Apply e1 es)))
(values e^ es^ rt)]
[`(All ,xs (,tys ... -> ,rt))
(define env^ (append (for/list ([x xs]) (cons x 'Type)) env))
(define env^^ (for/fold ([env^^ env^]) ([arg-ty ty*] [param-ty tys])
(match-types env^^ param-ty arg-ty)))
(debug 'type-check "match result" env^^)
(define targs
(for/list ([x xs])
(match (dict-ref env^^ x (lambda () #f))
[#f (error 'type-check "type variable ~a not deduced\nin ~v"
x (Apply e1 es))]
[ty ty])))
(values (Inst e^ ty targs) es^ (subst-type env^^ rt))]
[else (error 'type-check "expected a function, not ~a" ty)]))
(define/override ((type-check-exp env) e)
(verbose 'type-check "poly/exp begin" e env)
(define-values (e^ ty)
(match e
[(Lambda `([,xs : ,Ts] ...) rT body)
(for ([T Ts]) ((check-well-formed env) T))
((check-well-formed env) rT)
((super type-check-exp env) e)]
[(HasType e1 ty)
((check-well-formed env) ty)
((super type-check-exp env) e)]
[else ((super type-check-exp env) e)]))
(verbose 'type-check "poly/exp end" e e^ ty)
(values e^ ty))
(define/override ((type-check-def env) d)
(verbose 'type-check "poly/def" d)
(match d
[(Poly ts (Def f (and p:t* (list `[,xs : ,ps] ...)) rt info body))
(define ts-env (for/list ([t ts]) (cons t 'Type)))
(for ([p ps]) ((check-well-formed ts-env) p))
((check-well-formed ts-env) rt)
(define new-env (append ts-env (map cons xs ps) env))
(define-values (body^ ty^) ((type-check-exp new-env) body))
(check-type-equal? ty^ rt body)
(Poly ts (Def f p:t* rt info body^))]
[else ((super type-check-def env) d)]))
(define/override (type-check-program p)
(verbose 'type-check "poly/program" p)
(match p
[(Program info body)
(type-check-program (ProgramDefsExp info '() body))]
[(ProgramDefsExp info ds body)
(define ds^ (combine-decls-defs ds))
(define new-env (for/list ([d ds^])
(cons (def-name d) (fun-def-type d))))
(define ds^^ (for/list ([d ds^]) ((type-check-def new-env) d)))
(define-values (body^ ty) ((type-check-exp new-env) body))
(check-type-equal? ty 'Integer body)
(ProgramDefsExp info ds^^ body^)]))))
(define (type-check-poly p)
(send (new type-check-poly-class) type-check-program p))