{ nixpkgs ? import (fetchTarball https://github.com/NixOS/nixpkgs/archive/19.09.tar.gz) {} }: let inherit (nixpkgs) pkgs; inherit (pkgs) haskellPackages; haskellDeps = ps: with ps; [ base protolude containers ]; ghc = haskellPackages.ghcWithPackages haskellDeps; nixPackages = [ ghc pkgs.gdb haskellPackages.cabal-install ]; in pkgs.stdenv.mkDerivation { name = "env"; buildInputs = nixPackages; shellHook = '' export PS1="\n\[[hs:\033[1;32m\]\W\[\033[0m\]]> " ''; }