Instead of using symbolic references, use a dispatch table.

my $table = {
  INTEGER   => \&checkInteger,
  DATE      => \&checkDate,
  IPADDRESS => \&checkIpaddress,
  FOO       => \&checkFoo
};

if( defined $table->{uc $type} ) {
  $table->{uc $type}( $answer );
}
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(untested)

update: added untested code snippet