chore: move to flake

.envrc

@@ -1 +1 @@
-use_nix
+use flake .

flake.nix

@@ -0,0 +1,52 @@
+{
+  description = "Livebook Starter";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, flake-utils }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = import nixpkgs {
+          inherit system;
+        };
+
+        inherit (pkgs) inotify-tools terminal-notifier;
+        inherit (pkgs.lib) optionals;
+        inherit (pkgs.stdenv) isDarwin isLinux;
+
+        linuxDeps = optionals isLinux [ inotify-tools ];
+        darwinDeps = optionals isDarwin [ terminal-notifier ]
+          ++ (with pkgs.darwin.apple_sdk.frameworks; optionals isDarwin [
+          CoreFoundation
+          CoreServices
+        ]);
+
+      in
+      {
+        devShells = {
+          default = pkgs.mkShell {
+            packages = with pkgs;  [
+              beam.packages.erlangR26.elixir_1_15
+            ] ++ linuxDeps ++ darwinDeps;
+            shellHook = ''
+              # this allows mix to work on the local directory
+              mkdir -p .nix-mix .nix-hex
+              export MIX_HOME=$PWD/.nix-mix
+              export HEX_HOME=$PWD/.nix-hex
+              # make hex from Nixpkgs available
+              # `mix local.hex` will install hex into MIX_HOME and should take precedence
+              export MIX_PATH="${pkgs.beam.packages.erlangR26.hex}/lib/erlang/lib/hex/ebin"
+              export PATH=${pkgs.erlangR26}/bin:$MIX_HOME/escripts:$MIX_HOME/bin:$HEX_HOME/bin:bin:$PATH
+              export LANG=C.UTF-8
+              # keep your shell history in iex
+              export ERL_AFLAGS="-kernel shell_history enabled"
+
+              export MIX_ENV=dev
+            '';
+          };
+        };
+      });
+}