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Document match-lambda**' and match[*]/derived'

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Sam Tobin-Hochstadt 2011-06-15 17:50:42 -04:00
parent eaa156554a
commit d5b25eb500
1 changed files with 17 additions and 0 deletions
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collects/scribblings/reference/match.scrbl
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@ -380,6 +380,14 @@ Equivalent to @racket[(lambda (id) (match id clause ...))].
Equivalent to @racket[(lambda lst (match lst clause ...))].
}
@defform[(match-lambda** clause* ...)]{
Equivalent to @racket[(lambda (args ...) (match* (args ...) clause* ...))],
where the number of @racket[args ...] is computed from the number of patterns
appearing in each of the @racket[clause*].
}
@defform[(match-let ([pat expr] ...) body ...+)]{
Generalizes @racket[let] to support pattern bindings. Each
@ -457,6 +465,15 @@ A parameter that determines the comparison procedure used to check
whether multiple uses of an identifier match the ``same'' value. The
default is @racket[equal?].}
@deftogether[[@defform[(match/derived val-expr original-datum clause ...)]
@defform[(match*/derived (val-expr ...) original-datum clause*
...)]]]{
Like @racket[match] and @racket[match*] respectively, but includes a
sub-expression to be used as the source for all syntax errors within the form.
For example, @racket[match-lambda] expands to @racket[match/derived] so that
errors in the body of the form are reported in terms of @racket[match-lambda]
instead of @racket[match].}
@; ----------------------------------------------------------------------
@section{Library Extensions}