defined-or (or //) is not about speed: it is about logic and concise programming: it improves legibility and maintainability. I use the feature since perl-5.8.0 and it has been a very good reason to upgrade all my perl installations, even with customer sites. I cannot think of writing any perl script that does not use this feature. Silently I still wish the low-precedence keyword err (or dor given a bikeshed argument) will return one happy day.

Now imagine writing this with ternary:

my $file = $options{file} // $options{input_file} //
     get_default_option (""file") // get_default_option ("input_file")
+ //
     file_exists ("$ENV{WORK_DIR}/file.in") //
     file_exists ("$ENV{HOME}/project_in.file") or die;
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Or, preventing warnings

printf "%-20s: %s\n", $_, $options{$_} // "<undef>" for keys %options;

function (map { $_ // "default" } @values);

my @sorted = sort { ($a->{order} // 0) <=> ($b->{order} // 0) } @aoh;
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