and has very loose precedence, so your last example is parsed as 
(print "" =~ /.*/) and "" =~ /bar/

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The first regex match succeeds (thus the 1), and the result of the second one is discarded. Use && instead of and to get the result you want.

See also: perlop.

Perl 6 - second systems done right

In reply to Re: perl regular expressions and empty strings unexpected results by moritz
in thread perl regular expressions and empty strings unexpected results by bdimych

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