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improve docs for opaque types

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fix pr 10106

svn: r15723
This commit is contained in:
Sam Tobin-Hochstadt 2009-08-12 22:22:54 +00:00
parent 614980f6ec
commit 79c4f9651e
2 changed files with 3 additions and 2 deletions
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3
collects/typed-scheme/ts-reference.scrbl
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@ -258,7 +258,8 @@ Scheme.
@index["opaque"]{The fourth case} defines a new type @scheme[t]. @scheme[pred], imported from
module @scheme[m], is a predicate for this type. The type is defined
as precisely those values to which @scheme[pred] produces
@scheme[#t]. @scheme[pred] must have type @scheme[(Any -> Boolean)].
@scheme[#t]. @scheme[pred] must have type @scheme[(Any -> Boolean)].
Opaque types must be required lexically before they are used.
In all cases, the identifiers are protected with @rtech{contracts} which
enforce the specified types. If this contract fails, the module

2
collects/typed-scheme/typecheck/tc-structs.ss
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@ -51,7 +51,7 @@
(syntax-case nm/par ()
[nm (identifier? #'nm) (values #'nm #f #f (syntax-e #'nm) (make-F (syntax-e #'nm)))]
[(nm par) (let* ([parent0 (parse-type #'par)]
[parent (resolve-name parent0)])
[parent (if (Name? parent0) (resolve-name parent0) (tc-error/stx #'par "parent type not a valid structure name: ~a" (syntax->datum #'par)))])
(values #'nm parent0 parent (syntax-e #'nm) (make-F (syntax-e #'nm))))]
[_ (int-err "not a parent: ~a" (syntax->datum nm/par))]))