Ruby never does, but probably you wanted to say "if and only if" ?
The possibility to omit parenthesis is essential for many syntactic sugar and DSL approaches.
Compare "has" in Moose which looks like a keyword.
has 'first_name' => ( is => 'rw', isa => 'Str', );
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery
FootballPerl is like chess, only without the dice