diff options
Diffstat (limited to 'stlc-rec.rkt')
| -rw-r--r-- | stlc-rec.rkt | 48 |
1 files changed, 24 insertions, 24 deletions
diff --git a/stlc-rec.rkt b/stlc-rec.rkt index 3d099c2..8819116 100644 --- a/stlc-rec.rkt +++ b/stlc-rec.rkt @@ -13,33 +13,33 @@ ; Γ ⊢ unfold [μx.t] e: [x ↦ μx.t] t ;; (interpret Expr Table[Sym, Expr]): Value -(define (interpret expr [Γ #hash()]) - (interpret- (strip (desugar expr)) Γ)) -(define (interpret- expr Γ) +(define (interpret expr) + (interpret-core (strip (desugar expr)) #hash())) +(define (interpret-core expr Γ) (match expr ['sole 'sole] [n #:when (natural? n) n] [x #:when (dict-has-key? Γ x) (dict-ref Γ x)] - [`(fold ,e) `(fold ,(interpret- e Γ))] + [`(fold ,e) `(fold ,(interpret-core e Γ))] [`(unfold ,e) - (match (interpret- e Γ) + (match (interpret-core e Γ) [`(fold ,e) e] [e `(unfold e)])] [`(λ ,x ,e) `(λ ,x ,e ,Γ)] [`(,e1 ,e2) - (match (interpret- e1 Γ) + (match (interpret-core e1 Γ) [`(λ ,x ,e ,env) - (interpret- e (dict-set env x (interpret- e2 Γ)))] + (interpret-core e (dict-set env x (interpret-core e2 Γ)))] [e (err (format "applying arg ~a to unknown expression ~a" e2 e))])] [e (err (format "interpreting an unknown expression ~a" e))])) ;; (check Expr Type Table[Sym, Type]): Bool -(define (check expr with [Γ #hash()]) - (check- (desugar expr) with Γ)) -(define (check- expr with Γ) +(define (check expr with) + (check-core (desugar expr) with #hash())) +(define (check-core expr with Γ) ; (print (format "check: ~a" (fmt expr))) (match* (expr with) [('sole 'Unit) #t] @@ -48,26 +48,26 @@ (equal? (dict-ref Γ x) with)] [(`(fold (μ ,x ,t) ,e) `(μ ,x ,t)) - (check- e t (dict-set Γ x `(μ ,x ,t)))] + (check-core e t (dict-set Γ x `(μ ,x ,t)))] [(`(unfold (μ ,x ,t) ,e) with) - (and (check- e `(μ ,x ,t) Γ) + (and (check-core e `(μ ,x ,t) Γ) (equiv? with t #hash() #hash((x . `(μ ,x ,t)))))] [(`(λ (,x : ,t) ,e) `(,t1 → ,t2)) - (and (equal? t t1) (check- e t2 (dict-set Γ x t1)))] + (and (equal? t t1) (check-core e t2 (dict-set Γ x t1)))] [(`(,e1 ,e2) t) - (match (infer- e1 Γ) + (match (infer-core e1 Γ) [`(,t1 → ,t2) - (and (equal? t2 t) (equal? t1 (infer- e2 Γ)))] + (and (equal? t2 t) (equal? t1 (infer-core e2 Γ)))] [t #f])] [(e t) #f])) ;; (infer Expr Table[Sym, Type]): Type -(define (infer expr [Γ #hash()]) - (infer- (desugar expr) Γ)) -(define (infer- expr Γ) +(define (infer expr) + (infer-core (desugar expr) #hash())) +(define (infer-core expr Γ) ; (print (format "infer: ~a" (fmt expr))) (match expr ['sole 'Unit] @@ -77,21 +77,21 @@ (dict-ref Γ x)] [`(fold (μ ,x ,t) ,e) - (if (check- e t (dict-set Γ x `(μ ,x ,t))) `(μ ,x ,t) + (if (check-core e t (dict-set Γ x `(μ ,x ,t))) `(μ ,x ,t) (err (format "expected ~a to be of type ~a, got ~a" e t (infer e (dict-set Γ x `(μ ,x ,t))))))] [`(unfold (μ ,x ,t) ,e) - (if (check- e `(μ ,x ,t)) (replace t x `(μ ,x ,t)) + (if (check-core e `(μ ,x ,t)) (replace t x `(μ ,x ,t)) (err (format "expected ~a to be of type ~a, got ~a" - e `(μ ,x ,t) (infer- e Γ))))] + e `(μ ,x ,t) (infer-core e Γ))))] [`(λ (,x : ,t) ,e) - `(,t → ,(infer- e (dict-set Γ x t)))] + `(,t → ,(infer-core e (dict-set Γ x t)))] [`(,e1 ,e2) - (match (infer- e1 Γ) + (match (infer-core e1 Γ) [`(,t1 → ,t2) - (if (check- e2 t1 Γ) t2 + (if (check-core e2 t1 Γ) t2 (err (format "inferred argument type ~a does not match arg ~a" t1 e2)))] [t (err (format "expected → type on application body, got ~a" t))])] |