Resolution Function
First question - why are you trying to build a resolution function for a vector, or anything for that matter? What are you hoping to achieve? I dont understand how it can actually produce real hardware.
Secondly : AFAIK, you can only have a resolved sybtype, not a resolved signal. for example std_logic is a resolved version of std_ulogic.
subtype std_logic is resolved std_ulogic;
The only real world application of std_logic over std_ulogic is that it allows you to define tri-state buffers. Otherwise for what 99% of what people are doing they could std_ulogic.
Basically - in my opinion, unless you have a good reason for writing a resolution function - just dont.