Code:
alias num {
  if ($1 isnum) {
    var %d = $iif($count($1,.) == 1,1,0)
    if (!$prop && %s) { return $true }
    if ($prop == int && !%d) { return $true }
    if ($prop == dec && %d) { return $true }
  }
  elseif ($prop == hex && $regex($1,/^[0-9a-f]+$/i)) { return $true }
  return $false
}


$num(), returns $true if: The first param is a number/decimal.
$num().int, returns $true if the first param is an INT.
$num().dec, returns $true if there is a decimal, and only one decimal.
$num().hex, returns $true if the characters stay between 0 and F.

Note: It's false if there's two decimals. This is just an example of how you could check for these.