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generalize inferred types for invariant positions

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Sam Tobin-Hochstadt 2010-07-08 14:33:41 -04:00
parent bf6db901c6
commit 898c92eb1e
1 changed files with 7 additions and 2 deletions
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9
collects/typed-scheme/infer/infer-unit.rkt
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@ -520,14 +520,19 @@
;; variable: Symbol - variable to use instead, if v was a temp var for idx extension ;; variable: Symbol - variable to use instead, if v was a temp var for idx extension
(define (constraint->type v h #:variable [variable #f]) (define (constraint->type v h #:variable [variable #f])
(match v (match v
[(struct c (S X T)) [(c S X T)
(let ([var (hash-ref h (or variable X) Constant)]) (let ([var (hash-ref h (or variable X) Constant)])
;(printf "variance was: ~a~nR was ~a~nX was ~a~nS T ~a ~a~n" var R (or variable X) S T) ;(printf "variance was: ~a~nR was ~a~nX was ~a~nS T ~a ~a~n" var R (or variable X) S T)
(evcase var (evcase var
[Constant S] [Constant S]
[Covariant S] [Covariant S]
[Contravariant T] [Contravariant T]
[Invariant S]))])) [Invariant
(let ([gS (generalize S)])
(printf "Inv var: ~a ~a ~a ~a\n" v S gS T)
(if (subtype gS T)
gS
S))]))]))
;; Since we don't add entries to the empty cset for index variables (since there is no ;; Since we don't add entries to the empty cset for index variables (since there is no
;; widest constraint, due to dcon-exacts), we must add substitutions here if no constraint ;; widest constraint, due to dcon-exacts), we must add substitutions here if no constraint
;; was found. If we're at this point and had no other constraints, then adding the ;; was found. If we're at this point and had no other constraints, then adding the