add nix flake

Signed-off-by: Nicolas Froger <nicolas@kektus.xyz>

.envrc

@@ -0,0 +1,7 @@
+use_configsh() {
+  watch_file config.sh
+  eval "$(cat config.sh)"
+}
+
+use_flake
+use_configsh

flake.lock

@@ -0,0 +1,43 @@
+{
+  "nodes": {
+    "futils": {
+      "locked": {
+        "lastModified": 1656928814,
+        "narHash": "sha256-RIFfgBuKz6Hp89yRr7+NR5tzIAbn52h8vT6vXkYjZoM=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "7e2a3b3dfd9af950a856d66b0a7d01e3c18aa249",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1659526864,
+        "narHash": "sha256-XFzXrc1+6DZb9hBgHfEzfwylPUSqVFJbQPs8eOgYufU=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "478f3cbc8448b5852539d785fbfe9a53304133be",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixos-22.05",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "futils": "futils",
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,32 @@
+{
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-22.05";
+    futils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, futils } @ inputs:
+    let
+      inherit (nixpkgs) lib;
+      inherit (lib) recursiveUpdate;
+      inherit (futils.lib) eachDefaultSystem;
+
+      nixpkgsImport = system:
+        import nixpkgs {
+          inherit system;
+        };
+
+      defaultSystemOutputs = eachDefaultSystem (system:
+        let
+          pkgs = nixpkgsImport system;
+        in
+        {
+          devShells.default = pkgs.mkShell {
+            buildInputs = with pkgs; [
+              git
+              go
+            ];
+          };
+        });
+    in
+    defaultSystemOutputs;
+}