First a minor quibble: if you're talking about 'Nix data', then starting the conversation by talking about 'Nix-the-language' is rather misleading.
That aside, Nix allows you to create infinite datastructures, e.g.
$ nix eval --expr 'rec { z = { a = z; i = 5; }; }.z.a.a.a.i'
5
which you can't do with JSON.
But even if JSON did have some way of handling datastructure 'loops', it's still not helpful because of laziness. You almost never want to eagerly evaluate a Nix expression to produce what you seem to term 'Nix data', because you'll invoke the `derivation` built in function to create paths you never actually reference - this is why laziness is such an important property of Nix.
So I'm still not clear what user-facing part of Nix is isomorphic to JSON. If it's just "Nix types [0] are similar to JSON types" then...sure.
That aside, Nix allows you to create infinite datastructures, e.g.
which you can't do with JSON.But even if JSON did have some way of handling datastructure 'loops', it's still not helpful because of laziness. You almost never want to eagerly evaluate a Nix expression to produce what you seem to term 'Nix data', because you'll invoke the `derivation` built in function to create paths you never actually reference - this is why laziness is such an important property of Nix.
So I'm still not clear what user-facing part of Nix is isomorphic to JSON. If it's just "Nix types [0] are similar to JSON types" then...sure.
[0] https://nixos.org/manual/nix/stable/language/values