flake.nix: {formatter,packages,devShells}: new approach

Signed-off-by: s0me1newithhand7s <117505144+s0me1newithhand7s@users.noreply.github.com>

.envrc

@@ -0,0 +1 @@
+use flake || use nix

flake.nix

@@ -222,37 +222,60 @@
         nixpkgs,
         home-manager,
         ...
-    } @ inputs: {
+    } @ inputs: let
+       pkgs = self.inputs.nixpkgs.legacyPackages.x86_64-linux;
+       lib = self.inputs.nixpkgs.lib;
+    in {
         formatter = {
-            x86_64-linux = nixpkgs.legacyPackages.x86_64-linux.writeShellApplication {
+            x86_64-linux = self.packages.x86_64-linux.hand7sfmt;
+        };
+
+        packages = {
+            x86_64-linux = {
+                hand7sfmt = pkgs.writeShellApplication {
                     name = "hand7sfmt";
-                runtimeInputs = with nixpkgs.legacyPackages.x86_64-linux; [
+                    runtimeInputs = with pkgs; [
                         alejandra
                         statix
                         deadnix
                     ];
 
                     text = '' 
-                    ${nixpkgs.lib.getExe nixpkgs.legacyPackages.x86_64-linux.alejandra} \
+                        ${lib.getExe pkgs.alejandra} \
                         --experimental-config \
-                    ${nixpkgs.legacyPackages.x86_64-linux.writeText "alejandra.toml" ''
+                        ${pkgs.writeText "alejandra.toml" ''
                             indentation = "FourSpaces"
                         ''} \
                         --check \
-                    ${self} && ${nixpkgs.lib.getExe nixpkgs.legacyPackages.x86_64-linux.statix} \
+                        ${self}; \
+                        ${lib.getExe pkgs.statix} \
                         check \
                         --config \
-                    ${nixpkgs.legacyPackages.x86_64-linux.writeText "statix.toml" ''
+                        ${pkgs.writeText "statix.toml" ''
                             disabled = [
                                 "empty_pattern"
                             ]
                         ''} \
-                    ${self} && ${nixpkgs.lib.getExe nixpkgs.legacyPackages.x86_64-linux.deadnix} \
+                        ${self}; \
+                        ${lib.getExe pkgs.deadnix} \
                         --fail \
-                    ${self}
+                        ${self};
                     '';
                 };
             };
+        };
+
+        devShells = {
+            x86_64-linux = {
+                default = pkgs.mkShell {
+                    buildInputs = with pkgs; [
+                        alejandra
+                        statix
+                        deadnix
+                    ];
+                };
+            };
+        };
 
         homeConfigurations = {
             hand7s = home-manager.lib.homeManagerConfiguration {