ledger: do not build with python by default

{ stdenv, lib, fetchFromGitHub, cmake, boost, gmp, mpfr, libedit, python3

, installShellFiles, texinfo, gnused, usePython ? true }:

, installShellFiles, texinfo, gnused, usePython ? false }:

stdenv.mkDerivation rec {

  pname = "ledger";

    hash   = "sha256-0hN6Hpmgwb3naV2K1fxX0OyH0IyCQAh1nZ9TMNAutic=";

  };

  outputs = [ "out" "dev" "py" ];

  outputs = [ "out" "dev" ] ++ lib.optionals usePython [ "py" ];

  buildInputs = [

    (boost.override { enablePython = usePython; python = python3; })

    gmp mpfr libedit gnused

  ] ++ lib.optional usePython python3;

  ] ++ (if usePython

        then [ python3 (boost.override { enablePython = true; python = python3; }) ]

        else [ boost ]);

  nativeBuildInputs = [ cmake texinfo installShellFiles ];

  cmakeFlags = [

    "-DCMAKE_INSTALL_LIBDIR=lib"

    "-DBUILD_DOCS:BOOL=ON"

    (lib.optionalString usePython "-DUSE_PYTHON=true")

    "-DUSE_PYTHON:BOOL=${if usePython then "ON" else "OFF"}"

  ];

  # by default, it will query the python interpreter for it's sitepackages location