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* api-control.texi (if cond case): Describe SRFI 61 cond.

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* srfi-modules.texi (SRFI-61): New section.
(SRFI Support): Add SRFI-61 to menu.
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Marius Vollmer 2005-12-06 21:32:55 +00:00
parent e5547d5fc8
commit 43ed3b697e
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20
doc/ref/api-control.texi
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@ -108,6 +108,26 @@ the @code{cond}-expression. For the @code{=>} clause type,
the value of @var{test}. The result of this procedure application is
then the result of the @code{cond}-expression.
@cindex SRFI-61
@cindex general cond clause
@cindex multiple values and cond
One additional @code{cond}-clause is available as an extension to
standard Scheme:
@lisp
(@var{test} @var{guard} => @var{expression})
@end lisp
where @var{guard} and @var{expression} must evaluate to procedures.
For this clause type, @var{test} may return multiple values, and
@code{cond} ignores its boolean state; instead, @code{cond} evaluates
@var{guard} and applies the resulting procedure to the value(s) of
@var{test}, as if @var{guard} were the @var{consumer} argument of
@code{call-with-values}. Iff the result of that procedure call is a
true value, it evaluates @var{expression} and applies the resulting
procedure to the value(s) of @var{test}, in the same manner as the
@var{guard} was called.
The @var{test} of the last @var{clause} may be the symbol @code{else}.
Then, if none of the preceding @var{test}s is true, the
@var{expression}s following the @code{else} are evaluated to produce the

11
doc/ref/srfi-modules.texi
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@ -40,6 +40,7 @@ get the relevant SRFI documents from the SRFI home page
* SRFI-39:: Parameter objects
* SRFI-55:: Requiring Features.
* SRFI-60:: Integers as bits.
* SRFI-61:: A more general `cond' clause
@end menu
@ -2685,6 +2686,16 @@ element becomes the most significant bit in the return.
@end defun
@node SRFI-61
@subsection SRFI-61 - A more general @code{cond} clause
This SRFI extends RnRS @code{cond} to support test expressions that
return multiple values, as well as arbitrary definitions of test
success. SRFI 61 is implemented in the Guile core; there's no module
needed to get SRFI-61 itself. Extended @code{cond} is documented in
@ref{if cond case,, Simple Conditional Evaluation}.
@c srfi-modules.texi ends here
@c Local Variables: