Pinning Elixir and Erlang altogether

flake.nix

{
  description = "Pinning Elixir & Erlang altogether";

  # https://github.com/erlang/otp/archive/refs/tags/OTP-${VERSION}.zip
  # https://github.com/elixir-lang/elixir/archive/refs/tags/v${VERSION}.zip 

  inputs = {
    flake-utils.url = "github:numtide/flake-utils";
  };

  outputs = { flake-utils, nixpkgs, ... }: flake-utils.lib.eachDefaultSystem (system:
    let
      overlays = [
        (self: super: rec {
          erlang = super.beam.interpreters.erlangR25.override {
            version = "25.2";
            sha256 = "138xyqaa114fgv3gk01rawz9asg86maffj8yrhikgd8zsb8a57nd";
          };

          elixir = (super.beam.packagesWith erlang).elixir.override {
            version = "1.14.2";
            sha256 = "1w0wda304bk3j220n76bmv4yv0pkl9jca8myipvz7lm6fnsvw500";
          };
        })
      ];
      pkgs = import nixpkgs { inherit system; inherit overlays; };
    in
    {
      devShell = pkgs.mkShell {
        buildInputs = with pkgs; [
          erlang
          elixir
        ];
      };

      formatter = pkgs.nixpkgs-fmt;
    });
}