use warnings;
use strict;

use JSON;

my @array = qw(1 2 3);

open my $wfh, '>', 'file.ext'
  or die "can't open file for writing: $!";

print $wfh encode_json(\@array);

close $wfh;

open my $fh, '<', 'file.ext'
  or die "can't open file for reading: $!";

my $aref = decode_json(<$fh>);

close $fh;