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PR 10010

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svn: r13029
This commit is contained in:
Robby Findler 2009-01-07 16:06:37 +00:00
parent 05160bf931
commit 2afe7621b3
1 changed files with 17 additions and 5 deletions
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22
collects/scribblings/reference/contracts.scrbl
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@ -81,6 +81,13 @@ Takes any number of predicates and higher-order contracts and returns
a contract that accepts any value that any one of the contracts
accepts, individually.
The @scheme[or/c] result tests any value by applying the contracts in
order, from left to right, with the exception that it always moves the
non-@tech{flat contracts} (if any) to the end, checking them
last. Thus, a contract such as @scheme[(or/c (not/c real?)
positive?)] is guaranteed to only invoke the @scheme[positive?]
predicate on real numbers.
If all of the arguments are procedures or @tech{flat contracts}, the
result is a @tech{flat contract}. If only one of the arguments is a
higher-order contract, the result is a contract that just checks the
@ -95,11 +102,16 @@ calls @scheme[contract-first-order-passes?] with each of the
higher-order contracts. If only one returns true, @scheme[or/c] uses
that contract. If none of them return true, it signals a contract
violation. If more than one returns true, it signals an error
indicating that the @scheme[or/c] contract is malformed.
The @scheme[or/c] result tests any value by applying the contracts in
order, from left to right, with the exception that it always moves the
non-@tech{flat contracts} (if any) to the end, checking them last.}
indicating that multiple branches of the @scheme[or/c] each might
apply to the value. For example, this contract
@schemeblock[
(or/c (-> number? number?)
(-> string? string? string?))
]
cannot accept a function like this one: @scheme[(lambda args ...)]
since it cannot tell which of the two arrow contracts should be used
with the function.
}
@defproc[(and/c [contract (or/c contract? (any/c . -> . any/c))] ...)
contract?]{