In cases where nix code is expressed but not to be evaluated, quoting (idea from lisp) could be useful. This would be a good way to embed code as metadata.

For example in NixOS/nixpkgs#27394 (comment) where code is used for the documentation, it could be described like this:

input = `id 123`;
output = `123`;

Where the backtick is the quoting mechanism.

It would mean that the editor could still do syntax highlighting, the parsing phase of the language could still validate the syntax, but the evaluation your be deferred.

What do you think @edolstra? Let me know if you want more examples or think it's worth a RFC.

Cheers.
z