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explain shortcoming in define-opt/c

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related to #1238
This commit is contained in:
Robby Findler 2016-02-15 14:28:16 -06:00
parent 068af526de
commit f93e0df781
1 changed files with 11 additions and 2 deletions
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13
pkgs/racket-doc/scribblings/reference/contracts.scrbl
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@ -2985,7 +2985,8 @@ the name @racket[opt/c].
@defform[(define-opt/c (id id ...) expr)]{
This defines a recursive contract and simultaneously
optimizes it. Semantically, it behaves just as if
optimizes it. As long as the defined function terminates,
@racket[define-opt/c] behaves just as if
the @racket[-opt/c] were not present, defining a function on
contracts (except that the body expression must return a
contract). But, it also optimizes that contract definition,
@ -3008,7 +3009,15 @@ For example,
defines the @racket[bst/c] contract that checks the binary
search tree invariant. Removing the @racket[-opt/c] also
makes a binary search tree contract, but one that is
(approximately) 20 times slower.}
(approximately) 20 times slower.
Note that in some cases, a call to a function defined by
@racket[define-opt/c] may terminate, even if the corresponding
@racket[define]-based function would not terminate. This is a
shortcoming in @racket[define-opt/c] that we hope to understand
and fix at some point, but have no concrete plans currently.
}
@defthing[contract-continuation-mark-key continuation-mark-key?]{
Key used by continuation marks that are present during contract checking.