I'm not sure I prefer the strongly typed approach: I come from Lisp, so the approach is: "read it, validate it, and then wrap it in functions to hide the implem

I'm not sure I prefer the strongly typed approach: I come from Lisp, so the approach is: "read it, validate it, and then wrap it in functions to hide the implementation in case we change it." This works well in Lisp, where the line where objects end, and structs, lists and functions begin is hazy at best. Besides with a bit of wrangling, you could probably just pass your validated serialized data to the object constructor as the arguments. Or you could just write a struct, which is simpler than an object, provides O(1) access, and you can still probably easily pass your datastructure, or something close, into the constructor as the arglist.