These two are not exactly the same... they will behave differently if $bar is defined but has a non-true value (like 0). That's because the || operator tests for truth, while the much-to-be-desired // operator (in Perl6) will test for defined-ness. So in Perl6, you could write it as:

$foo = $bar;
$foo //= $default_for_foo;
[download]

or, I imagine, like this:

$foo = $bar // $default_for_foo;
[download]

-- Mike

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just,my${.02}