{
  description = "libFenrir";

  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/nixos-23.05";
    nixpkgs-unstable.url = "github:nixos/nixpkgs/nixos-unstable";
    rust-overlay.url = "github:oxalica/rust-overlay";
    flake-utils.url  = "github:numtide/flake-utils";
  };

  outputs = flakes@{ self, nixpkgs, nixpkgs-unstable, rust-overlay, flake-utils, ... }:
  flake-utils.lib.eachDefaultSystem (system:
    let
      overlays = [ (import rust-overlay) ];
      pkgs = import nixpkgs {
        inherit system overlays;
      };
      pkgs-unstable = import nixpkgs-unstable {
        inherit system overlays;
      };
    in
    {
      devShells.default = pkgs.mkShell {
        buildInputs = with pkgs; [
          git
          gnupg
          openssh
          openssl
          pkg-config
          exa
          fd
          #(rust-bin.stable.latest.default.override {
          # go with nightly to have async fn in traits
          #(rust-bin.nightly."2023-02-01".default.override {
          #  #extensions = [ "rust-src" ];
          #  #targets = [ "arm-unknown-linux-gnueabihf" ];
          #})
          clippy
          cargo-watch
          cargo-flamegraph
          cargo-license
          lld
          rust-bin.stable."1.69.0".default
          rustfmt
          rust-analyzer
          # fenrir deps
          hwloc
        ];
        shellHook = ''
          # use zsh or other custom shell
          USER_SHELL="$(grep $USER /etc/passwd | cut -d ':' -f 7)"
          if [ -n "$USER_SHELL" ]; then
            exec $USER_SHELL
          fi
        '';
      };
    }
  );
}