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Document the nullary-variant period in alt patterns

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Brian Anderson 2011-10-28 16:18:16 -07:00
parent ba1df0eda9
commit 6afecc37e3
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doc/rust.texi
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@ -3396,12 +3396,21 @@ alt x @{
cons(10, _) @{
process_ten();
@}
nil. @{
ret;
@}
_ @{
fail;
@}
@}
@end example
Note in the above example that @code{nil} is followed by a period. This is
required syntax for pattern matching a nullary tag variant, to distingush the
variant @code{nil} from a binding to variable @code{nil}. Without the period
the value of @code{x} would be bound to variable @code{nil} and the compiler
would issue an error about the final wildcard case being unreachable.
Multiple alternative patterns may be joined with the @code{|} operator. A
range of values may be specified with @code{to}. For example: