@azazel75 The edition field actually was implemented, but I removed it.The main use case was to support future language changes, but but this creates a circular problem: you have to parse/evaluate flake.nix to get the edition, but you can’t do that if you don’t know the edition…
@ElvishJerricco Yes, nix fmt is a convenience command that could also be done using nix run. But that also applies to e.g. cargo fmt. The eventual goal is to establish a blessed, default formatting style (see RFC 101). At that point the formatter could be included in Nix itself.