Not sure if your perl version is too old?
Use Perl::MinimumVersion/perlver
$ perlver foo.pl
--------------------------------------
| file | explicit | syntax | external |
| -------------------------------------- |
| foo.pl | ~ | v5.10.0 | n/a |
| -------------------------------------- |
| Minimum explicit version : ~ |
| Minimum syntax version : v5.10.0 |
| Minimum version of perl : v5.10.0 |
--------------------------------------
$ perlver --blame foo.pl
------------------------------------------------------------
File : foo.pl
Line : 3
Char : 17
Rule : _perl_5010_operators
Version : 5.010
------------------------------------------------------------
~~
------------------------------------------------------------
$ cat foo.pl
my $foo = 6;
my @bar = ( 3,6, 9 );
print 1 if $foo ~~ @bar;
Then you can add use v5.10.0; or use 5.010000; to your foo.pl, and perl will do the version check