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-rw-r--r--stlc-fix.rkt42
1 files changed, 21 insertions, 21 deletions
diff --git a/stlc-fix.rkt b/stlc-fix.rkt
index cb6a592..e8f15e6 100644
--- a/stlc-fix.rkt
+++ b/stlc-fix.rkt
@@ -4,35 +4,35 @@
;; The Simply-Typed Lambda Calculus, with general recursion
;; (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)]
[`(fix ,e)
- (match (interpret- e Γ)
+ (match (interpret-core e Γ)
[`(λ ,x ,e ,env)
; FIXME: unsure what should be Γ and what should be env
- (interpret- e (dict-set Γ x `(fix (λ ,x ,e ,Γ))))]
+ (interpret-core e (dict-set Γ x `(fix (λ ,x ,e ,Γ))))]
[e (err (format "applying fix to unknown expression ~a" e))])]
[`(λ ,id ,body) `(λ ,id ,body ,Γ)]
[`(λ ,id ,body ,env) `(λ ,id ,body ,env)]
[`(,body ,arg)
- (match (interpret- body Γ)
+ (match (interpret-core body Γ)
[`(λ ,id ,body ,env)
- (interpret- body (dict-set env id (interpret- arg Γ)))]
+ (interpret-core body (dict-set env id (interpret-core arg Γ)))]
[e (err (format "applying arg ~a to unknown expression ~a" arg 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)
(let ([with (if (dict-has-key? Γ with) (dict-ref Γ with) with)])
(match* (expr with)
[('sole 'Unit) #t]
@@ -41,22 +41,22 @@
(equal? (dict-ref Γ x) with)]
[(`(fix ,e) with)
- (check- (infer- e) `(,with → ,with) Γ)]
+ (check-core (infer-core e) `(,with → ,with) Γ)]
[(`(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)
(match expr
['sole 'Unit]
[n #:when (natural? n) 'Nat]
@@ -64,16 +64,16 @@
(dict-ref Γ x)]
[`(fix ,e)
- (match (infer- e Γ)
+ (match (infer-core e Γ)
[`(,t → ,t) t]
[t (err (format "fix expects a term of type t → t, got ~a" t))])]
[`(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))])]