Yes. See:

    my @exts = qw/foo bar baz/;
    my %exts;

    @exts{@exts} = @exts;

    use Data::Dumper;
    print Dumper \%exts;
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produces:

    $VAR1 = {
          'foo' => 'foo',
          'baz' => 'baz',
          'bar' => 'bar'
        };
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I might point out that nothing answers a question so well as testing a bit of code out yourself. :)