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fix descripting of struct-field-index (PR 9685)

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svn: r11223
This commit is contained in:
Matthew Flatt 2008-08-13 18:51:03 +00:00
parent 962fea6513
commit caf7bdd363
1 changed files with 6 additions and 4 deletions
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10
collects/scribblings/reference/define-struct.scrbl
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@ -106,8 +106,7 @@ multiple times, attaches a property value to the structure type; see
@margin-note{Use the @scheme[prop:procedure] to property implement an
@as-index{applicable structure}, use @scheme[prop:evt] to create a
structure type whose instances are @tech{synchronizable events}, and
so on. By convention, property names usually start with
@schemeidfont{prop:}.}
so on. By convention, property names start with @schemeidfont{prop:}.}
The @scheme[#:prefab] option obtains a @techlink{prefab} (pre-defined,
globally shared) structure type, as opposed to creating a new
@ -162,11 +161,14 @@ cp
This form can only appear as an expression within a
@scheme[define-struct] form; normally, it is used with
@scheme[#:property], especially for a property like
@scheme[prop:procedure]. The result of
@scheme[prop:procedure]. The result of a @scheme[struct-field-index]
expression is an exact, non-negative integer that corresponds to the
position within the structure declaration of the field named by
@scheme[field-id].
@defexamples[
#:eval posn-eval
(define-struct mood-procedure ([base] rating)
(define-struct mood-procedure (base rating)
#:property prop:procedure (struct-field-index base))
(define happy+ (make-mood-procedure add1 10))
(happy+ 2)