shell.nix

{ nixpkgs ? import <nixpkgs> {}, compiler ? "ghc7103" }:

let

  inherit (nixpkgs) pkgs;

  f = { mkDerivation, base, containers, haskeline, llvm-general
      , llvm-general-pure, mtl, parsec, stdenv, transformers
      }:
      mkDerivation {
        pname = "kaleidoscope";
        version = "0.1.0.0";
        src = ./.;
        isLibrary = true;
        isExecutable = true;
        libraryHaskellDepends = [
          base haskeline llvm-general llvm-general-pure mtl transformers
        ];
        executableHaskellDepends = [
          base containers haskeline llvm-general llvm-general-pure mtl parsec
          transformers
        ];
        homepage = "https://github.com/sdiehl/kaleidoscope";
        description = "Haskell Kaleidoscope tutorial";
        license = stdenv.lib.licenses.mit;
      };

  haskellPackages = if compiler == "default"
                       then pkgs.haskellPackages
                       else pkgs.haskell.packages.${compiler};

  drv = haskellPackages.callPackage f {};

in

  if pkgs.lib.inNixShell then drv.env else drv