ref() is a good start. Scalar::Util provides a number of other options, such as looks_like_number() (which tells you if something is probably a number), blessed() (which returns the class it's blessed into, if any). As for int vs. float, that's easy - int($a) == $a means it's an int.

The important point here is that when you program in Perl, you shouldn't have to worry about int vs. float. Personally, I tend to not worry about anything except reference, object, and non-reference.