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Whitespace fixes, small optimizations of union cases.

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This commit is contained in:
Sam Tobin-Hochstadt 2011-09-06 08:02:12 -04:00
parent 43c0177895
commit 64a1aee65d
1 changed files with 94 additions and 78 deletions
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20
collects/typed-racket/types/subtype.rkt
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@ -356,9 +356,25 @@
(subtype* A0 other t*)
(fail! s t)))]
;; for unions, we check the cross-product
[((Union: es) t) (or (and (andmap (lambda (elem) (subtype* A0 elem t)) es) A0)
;; some special cases for better performance
[((Union: (list e1 e2)) t)
(if (and (subtype* A0 e1 t) (subtype* A0 e2 t))
A0
(fail! s t))]
[(s (Union: es)) (or (and (ormap (lambda (elem) (subtype*/no-fail A0 s elem)) es) A0)
[((Union: (list e1 e2 e3)) t)
(if (and (subtype* A0 e1 t) (subtype* A0 e2 t) (subtype* A0 e3 t))
A0
(fail! s t))]
[((Union: es) t)
(if (for/and ([elem (in-list es)])
(subtype* A0 elem t))
A0
(fail! s t))]
[(s (Union: es))
(if (for/or ([elem (in-list es)])
(with-handlers ([exn:subtype? (lambda _ #f)])
(subtype* A0 s elem)))
A0
(fail! s t))]
;; subtyping on immutable structs is covariant
[((Struct: nm _ flds proc _ _ _ _) (Struct: nm* _ flds* proc* _ _ _ _)) (=> nevermind)