shell.nix

with (import <nixpkgs> {}).pkgs;
with import <nixpkgs/pkgs/development/haskell-modules/lib.nix> { inherit pkgs; };
let
  QuickCheck = haskellPackages.QuickCheck_2_9_2;
  quickcheck-io = haskellPackages.quickcheck-io.override { inherit QuickCheck; };
  quickcheck-instances = haskellPackages.quickcheck-instances.override { inherit QuickCheck; };
  hspec-meta = haskellPackages.hspec-meta.override { inherit QuickCheck quickcheck-io;};
  hspec-core = haskellPackages.hspec-core.override { inherit QuickCheck quickcheck-io hspec-meta;};
  hspec = haskellPackages.hspec.override { inherit QuickCheck hspec-core hspec-meta; };
  http-api-data = (doJailbreak haskellPackages.http-api-data_0_3_1).override {inherit QuickCheck hspec quickcheck-instances; };
  servant = haskellPackages.servant_0_9_0_1.override {inherit http-api-data; };
  servant-server = haskellPackages.servant-server_0_9_0_1.override {inherit http-api-data servant; };
  servant-client = haskellPackages.servant-client_0_9_0_1.override {inherit http-api-data servant servant-server;};
in
(haskellPackages.callPackage ./. {inherit http-api-data servant servant-client;}).env