sub aindex (\@$;$) {
  my ($aref, $val, $pos) = @_;
  for ($pos ||= 0; $pos < @$aref; $pos++) { 
    return $pos if $aref->[$pos] eq $val;
  }
  return -1;
}
sub raindex (\@$;$) {
  my ($aref, $val, $pos) = @_;
  for (defined $pos or $pos = $#$aref; $pos >= 0; $pos--) {
    return $pos if $aref->[$pos] eq $val;
  }
  return -1;
}

## EXAMPLE ##

my @l = qw(are you looking for something here or are you not);
print " ", aindex @l, 'you';
print " ", aindex @l, 'you', 5;
print " ", raindex @l, 'you';
print " ", raindex @l, 'you', 5;

# output:  1 8 8 1
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