use constant SNaN => unpack 'd',pack 'Q', 0x7ff0000000000001;

##</code><code>##

C:\test>perl -MO=Deparse -le"use enum qw[false true]; print 'fred' if false; print 'bill' if true"
use enum ('false', 'true');

'???';
print 'bill';
-e syntax OK

##</code><code>##

C:\test>perl -MO=Deparse -le"sub PI(){ 2*atan2(1,0) }; print PI; if( PI == PI ) { print 'Here'; }"
BEGIN { $/ = "\n"; $\ = "\n"; }
sub PI () { 3.1415926535897931 }
print 3.1415926535897931;
do {
    print 'Here'
};
-e syntax OK

##</code><code>##

C:\test>perl -MO=Deparse -le"use constant SNaN => unpack'd', pack'Q',0x7ff0000000000001; print SNaN; if( SNaN != SNaN ) { print 'here'; }"
BEGIN { $/ = "\n"; $\ = "\n"; }
use constant ('SNaN', unpack('d', pack('Q', 9218868437227405313)));
print unpack("F", pack("h*", "1000000000000ff7"));
do {
    print 'here'
};
-e syntax OK

C:\test>perl -MO=Deparse -le"use constant SNaN => unpack'd', pack'Q', 0x7ff0000000000001; print SNaN; if( SNaN == SNaN ) { print 'here'; }"
BEGIN { $/ = "\n"; $\ = "\n"; }
use constant ('SNaN', unpack('d', pack('Q', 9218868437227405313)));
print unpack("F", pack("h*", "1000000000000ff7"));
'???';
-e syntax OK