constant_folding.pl

#!/usr/bin/env perl
use strict;
use warnings;
use feature qw/ say /;
use Data::Lock qw/ dlock /;

use constant C_TRUE  => 1;
use constant C_FALSE => 0;
dlock my $D_TRUE  = 1;
dlock my $D_FALSE = 0;
my $V_TRUE  = 1;
my $V_FALSE = 0;
my $I_TRUE  = 1;
my $I_FALSE = 0;
Internals::SvREADONLY($I_TRUE,  1);
Internals::SvREADONLY($I_FALSE, 1);

say 'C_TRUE'  if C_TRUE;
say 'C_FALSE' if C_FALSE;
say 'D_TRUE'  if $D_TRUE;
say 'D_FALSE' if $D_FALSE;
say 'V_TRUE'  if $V_TRUE;
say 'V_FALSE' if $V_FALSE;
say 'I_TRUE'  if $I_TRUE;
say 'I_FALSE' if $I_FALSE;

__END__
perl -MO=Deparse ./constant_folding.pl
use Data::Lock ('dlock');
use constant ('C_TRUE', 1);
use constant ('C_FALSE', 0);
use warnings;
use strict;
use feature 'say';
dlock(my $D_TRUE = 1);
dlock(my $D_FALSE = 0);
my $V_TRUE = 1;
my $V_FALSE = 0;
my $I_TRUE = 1;
my $I_FALSE = 0;
&Internals::SvREADONLY(\$I_TRUE, 1);
&Internals::SvREADONLY(\$I_FALSE, 1);
say 'C_TRUE';
'???';
;
say 'D_TRUE' if $D_TRUE;
say 'D_FALSE' if $D_FALSE;
say 'V_TRUE' if $V_TRUE;
say 'V_FALSE' if $V_FALSE;
say 'I_TRUE' if $I_TRUE;
say 'I_FALSE' if $I_FALSE;
./constant_folding.pl syntax OK