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Add examples for _? C type

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This commit is contained in:
Asumu Takikawa 2016-06-07 15:19:59 -04:00
parent f0003da766
commit 2a222a8f15
1 changed files with 15 additions and 1 deletions
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16
pkgs/racket-doc/scribblings/foreign/types.scrbl
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@ -938,7 +938,21 @@ A @tech{custom function type} that is a marker for expressions that
should not be sent to the foreign function. Use this to bind local should not be sent to the foreign function. Use this to bind local
values in a computation that is part of an ffi wrapper interface, or values in a computation that is part of an ffi wrapper interface, or
to specify wrapper arguments that are not sent to the foreign function to specify wrapper arguments that are not sent to the foreign function
(e.g., an argument that is used for processing the foreign output).} (e.g., an argument that is used for processing the foreign output).
Examples:
@racketblock[
(_fun _? (code:comment "not sent to foreign function")
_int -> _int)
(_fun [init : _?] (code:comment "init is used for pre-processing")
[boxed : (_box _int) = (box init)]
-> _void)
(_fun [offset : _?] (code:comment "offset is used for post-processing")
-> [res : _int]
-> (+ res offset))
]
}
@defform/subs[#:literals (i o io) @defform/subs[#:literals (i o io)