use strict;
use warnings;
use Data::Dump qw(dump);

$_ = $0;
sub f { print('->f()') . '.0'; }

my %h = (
     f    => '  F',
    +f    => ' +F',
   + f    => '+ F',
    -f    => ' -F',
   - f    => '- F',
     f()  => ' ()',
    -f()  => '-()',
   - f()  => '-()',
    +f()  => '+()',
);
print "\n",dump(\%h),"\n";