# Anything to the left of a 
# => is treated as like it's 'single quoted'
# That means variables are not interpolated.

##</code><code>##

perl -MData::Dumper -le 
'$foo = "blah"; %a = ( $foo => 42 ); print Dumper \%a'
$VAR1 = {
          'blah' => 42
        };