Alex,
I agree to most what you wrote and explained.
Structures and lists are useful elements and marking them with (curly) brackets
helps to scan and parse them easily.
The motivation to add nesting is also reasonable to me but I would like to
restrict it to a smaller minimum than you do.
The deeper nesting example (3b) is already very complex (I always had problems
with programming in LISP)
As long as we do not have good examples why we need nesting deeper than level
1, I would like to restrict it to that.
So only allowing a value to be
an atom
a list/structure of atoms
a list/structure of lists/structures of atoms
By the way: What is the current status of atoms? Strings, integers and floats?
Regards
Martin