env: add simple env to test out buildEnv and profiles

Justfile

@@ -17,6 +17,18 @@ install host:
                 --file ./default.nix \
                 --attr "nixosConfigurations.{{ host }}"
 
+env name action profilePath="~/.environments":
+        #!/usr/bin/env bash
+        # 1) realize the buildEnv derivation
+        # 2) set the environment to it
+        drv=$(nix-build -E "
+                let sources = import ./nix/sources.nix {};
+                    pkgs = import sources.nixpkgs {};
+                 in pkgs.callPackage ./nix/environments/{{ name }}.nix {}
+                ")
+        mkdir -p {{ profilePath }}
+        nix-env --{{ action }} "$drv" --profile {{ profilePath }}"/{{ name }}"
+
 update:
         niv update nixpkgs
         niv update nur

nix/environments/nix.nix

@@ -0,0 +1,11 @@
+{
+  buildEnv,
+  #
+  nixfmt-rfc-style,
+}:
+buildEnv {
+  name = "nix";
+  paths = [
+    nixfmt-rfc-style
+  ];
+}