Expose new-cli `--json` commands in the repl

[roberth]

Is your feature request related to a problem? Please describe.

jq is fun, but not as fun as Nix.

We could add a primop to the repl only, to do all the dirty things that the language can't normally do, and manipulate the result with Nix in the repl.

Describe the solution you'd like

Something like

nix-repl> ping = builtins.runCLI ["store" "ping"]

nix-repl> ping.url
"daemon"

There's a whole bunch more interesting commands of course.

Describe alternatives you've considered

nix-repl> :nix store ping
Store URL: daemon
Version: 2.23.1
Trusted: 1

nix-repl> :sh nix store ping
[ ... similar ... ]

These don't produce proper values though.

Additional context

Priorities

Add 👍 to issues you find important.

[thufschmitt]

$ nix repl --option allow-unsafe-native-code-during-evaluation true
Welcome to Nix 2.20.0pre20240127_4025409. Type :? for help.

nix-repl> runNixCommand = command: builtins.exec ["sh" "-c" ''nix-instantiate --eval --expr "{ json }: builtins.fromJSON json" --argstr json "$(nix ${command} --json)"'' ]

nix-repl> runNixCommand "store info"                                                                                                               
{ trusted = 1; url = "daemon"; version = "2.20.0pre20240127_4025409"; }

🙈

[nixos-discourse]

This issue has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/2024-03-11-nix-team-meeting-132/42960/1