with import <nixpkgs> {};

let
  ocamlPackages = pkgs.recurseIntoAttrs pkgs.ocamlPackages_latest;
  ocamlVersion = (builtins.parseDrvName ocamlPackages.ocaml.name).version;
  findlibSiteLib = "${ocamlPackages.findlib}/lib/ocaml/${ocamlVersion}/site-lib";
  ocamlInit = pkgs.writeText "ocamlinit" ''
    let () =
      try Topdirs.dir_directory "${findlibSiteLib}"
      with Not_found -> ()
    ;;

    #use "topfind";;
    #thread;;
    #require "core";;
    #require "core.syntax";;
  '';
in
stdenv.mkDerivation rec {
  name = "rwo-shell";
  src = null;
  buildInputs = with ocamlPackages;
    [ ocaml
      core
      core_extended
      findlib
      utop
      dune
    ];
  shellHook = ''
    alias utop="utop -init ${ocamlInit}"
    alias ocaml="ocaml -init ${ocamlInit}"
  '';
}