Describe the bug

This json output makes the fatal mistake of putting a dictionary inside a dictionary. This is not extensible; we'll have to break the format.

Definitions

• dictionary: a map from names to things that all have the same type (C++ std::map)
• record: a fixed set of attributes each with their own type (C++ struct)

Steps To Reproduce

Try to add a non-setting field to the store description object, e.g. the URI scheme. You can't, because it will be interpreted as an option.

Expected behavior

A clear and concise description of what you expected to happen.

nix-env --version output

Additional context

We need JSON guidelines.

• Guidelines for extensible JSON #7823

Priorities

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