default.nix

# where i would i put the following in this default.nix?
#  servant-src = pkgs.fetchFromGitHub { 
#    owner = "haskell-servant";
#    repo = "servant";
#    rev = "5998429" ;
#    sha256 = "1p21x6df0j6zsmjf4z9cahbi15mar80na8rx8hl9mkb9pfrj9dic";
#  };
#  servant-client-ghcjs = pkgs.haskell.packages.ghcjs.callCabal2nix "${servant-src}/servant-client-ghcjs" {};

with (import (builtins.fetchTarball {
  url = "https://github.com/dmjio/miso/archive/561ffad.tar.gz";
  sha256 = "1wwzckz2qxb873wdkwqmx9gmh0wshcdxi7gjwkba0q51jnkfdi41";
}) {});

let
  server = pkgs.haskell.packages.ghc865.callCabal2nix "app" ./. {};
  client = pkgs.haskell.packages.ghcjs86.callCabal2nix "app" ./. {};
in
{
  inherit server client;
  app = pkgs.runCommand "my-ghcjs-app" { inherit client server; } ''
    mkdir -p $out/{bin,static}
    cp ${server}/bin/* $out/bin/
    ${pkgs.tree}/bin/tree -a ${client}
    cp ${client}/bin/client.jsexe/all.js $out/static/
  '';
}

shell.nix

{ useServer ? false }:
with (import ./default.nix);
if useServer
  then server.env
  else client.env