add elixir template

elixir/flake.nix

@@ -0,0 +1,22 @@
+{
+  description = "A Nix-flake-based Elixir development environment";
+
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/release-23.05";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = {
+    self,
+    nixpkgs,
+    flake-utils,
+  }:
+    flake-utils.lib.eachDefaultSystem
+    (system: let
+      pkgs = import nixpkgs {
+        inherit system;
+      };
+    in {
+      devShells.default = pkgs.callPackage ./shell.nix {};
+    });
+}

elixir/shell.nix

@@ -0,0 +1,18 @@
+{pkgs,...}:
+pkgs.mkShell {
+         buildInputs = [
+          pkgs.elixir
+          pkgs.elixir-ls
+          pkgs.erlang
+         ];
+         shellHook = ''
+           export MIX_HOME=$PWD/.mix
+           export HEX_HOME=$PWD/.hex
+           echo 'Elixir version:'
+           elixir --version
+           echo 'Erlang version:'
+           erl -version
+           echo 'Welcome to Elixir shell!'
+           echo 'Run `iex` to start the interactive shell'
+          '';
+      }