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Compare numeric unions using a linear scan.

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This commit is contained in:
Vincent St-Amour 2011-09-12 18:12:24 -04:00
parent c63b5873e3
commit 8ae1a903fa
1 changed files with 11 additions and 5 deletions
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16
collects/typed-racket/types/subtype.rkt
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@ -367,11 +367,17 @@
[((Union: l1) (Union: l2))
(=> unmatch)
(if (and (eq? ks 'number) (eq? kt 'number))
(if (for/and ([elem1 (in-list l1)])
;; since the lists are sorted, this could be optimized further
(memq elem1 l2))
A0
(fail! s t))
;; l1 should be a subset of l2
;; since union elements are sorted, a linear scan works
(let loop ([l1 l1] [l2 l2])
(cond [(null? l1)
A0]
[(null? l2)
(fail! s t)]
[(eq? (car l1) (car l2))
(loop (cdr l1) (cdr l2))]
[else
(loop l1 (cdr l2))]))
(unmatch))]
[((Union: (list e1 e2)) t)
(if (and (subtype* A0 e1 t) (subtype* A0 e2 t))