-- initialize empty table
P = {}
P.a = "bla1"
P.b = "bla2"
and so on.
Now I can refer to each value by name, and I also can easily iterate
over the table P.
This looks to me like one of the HList-based record systems. But that could get you into hot water fairly quickly, as while the record/lens packages try to cover up the ugliness, it's all based on some fairly complex type hackery.