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Updated documentation for "contract" form.

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svn: r17910
This commit is contained in:
Carl Eastlund 2010-01-31 04:30:55 +00:00
parent 1d4cdbeb45
commit a2226c965a
1 changed files with 13 additions and 27 deletions
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40
collects/scribblings/reference/contracts.scrbl
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@ -817,7 +817,7 @@ The @scheme[define-struct/contract] form only allows a subset of the
positive-blame-expr negative-blame-expr)
(contract contract-expr to-protect-expr
positive-blame-expr negative-blame-expr
contract-source-info)]]{
value-name-expr source-location-expr)]]{
The primitive mechanism for attaching a contract to a value. The
purpose of @scheme[contract] is as a target for the expansion of some
@ -830,35 +830,21 @@ is the result of the @scheme[to-protect-expr] expression, but with the
contract specified by @scheme[contract-expr] enforced on
@scheme[to-protect-expr].
The values of @scheme[positive-blame-expr] and
@scheme[negative-blame-expr] must be symbols indicating how to assign
blame for positive and negative positions of the contract specified by
@scheme[contract-expr].
The values of @scheme[positive-blame-expr] and @scheme[negative-blame-expr]
indicate how to assign blame for positive and negative positions of the contract
specified by @scheme[contract-expr]. They may be any value, and are formatted
as by @scheme[display] for purposes of contract violation error messages.
If specified, @scheme[contract-source-info], indicates where the
contract was assumed. Its value must be a either:
@itemize[
@item{a list of two elements: @scheme[srcloc] struct and
either a string or @scheme[#f]. The srcloc struct indicates
where the contract was assumed. Its @tt{source} field
should be a syntax object, and @scheme[module-path-index-resolve]
is called on it to extract the path of syntax object.
If specified, @scheme[value-name-expr] indicates a name for the protected value
to be used in error messages. If not supplied, or if @scheme[value-name-expr]
produces @scheme[#f], no name is printed. Otherwise, it is also formatted as by
@scheme[display].
If the second element of
the list is not @scheme[#f], it is used as the name of the
identifier whose contract was assumed.}
If specified, @scheme[source-location-expr] indicates the source location
reported by contract violations. The expession must produce a @scheme[srcloc]
structure, @tech{syntax object}, @scheme[#f], or a list or vector in the format
accepted by the third argument to @scheme[datum->syntax].
@item{a syntax object specifying the
source location of the location where the contract was assumed. If the
syntax object wraps a symbol, the symbol is used as the name of the
primitive whose contract was assumed.}
]
If absent, it defaults to the source location of the
@scheme[contract] expression with no identifying name.
The second form above is not recommended, because mzscheme strips
source location information from compiled files.
}
@; ------------------------------------------------------------------------