update exports and test

Makefile

@@ -1,4 +1,4 @@
 default: test
 
 test:
-	nix-shell -A shell --pure --run './test.bash'
+	nix-shell --pure --run './test.bash'

README.md

@@ -9,22 +9,22 @@ Derivations for easily downloading Dhall binaries and putting them to use.
 You cn get an appropriate nix-shell with the binaries installed by first testing this with:
 
 ```
-nix-shell -A shell
+nix-shell
 ```
 
 ## Installation
 
 You might choose to simply copy the derivations from this repository, or you can fetch the git/Github repo using the various helpers:
 
-```nix
+```
 > nix repl
 nix-repl> pkgs = import <nixpkgs> {}
 
 nix-repl> drvs = import (pkgs.fetchFromGitHub {
   owner = "justinwoo";
   repo = "easy-dhall-nix";
-  rev = "87406a76409c16bbd7511e397cfc52e1c58954e3";
-  sha256 = "1sjpckyhvlks5yls0qqfd0iaf7pxp1sp3dikqh41lg6xsxx6lqhi";
+  rev = # some REV
+  sha256 = # some SHA
 }) {}
 
 nix-repl> drvs.dhall-simple

default.nix

@@ -1,21 +1,8 @@
 { pkgs ? import <nixpkgs> {} }:
 
-let
+{
   dhall-simple = import ./dhall-simple.nix {};
   dhall-json-simple = import ./dhall-json-simple.nix {};
   dhall-bash-simple = import ./dhall-bash-simple.nix {};
   dhall-text-simple = import ./dhall-text-simple.nix {};
-in {
-  inherit dhall-simple;
-
-  shell = pkgs.stdenv.mkDerivation {
-    name = "easy-dhall-nix-shell";
-
-    buildInputs = [
-      dhall-simple
-      dhall-json-simple
-      dhall-bash-simple
-      dhall-text-simple
-    ];
-  };
 }

shell.nix

@@ -0,0 +1,6 @@
+{ pkgs ? import <nixpkgs> {} }:
+
+pkgs.stdenv.mkDerivation {
+  name = "easy-dhall-nix-shell";
+  buildInputs = builtins.attrValues (import ./default.nix { inherit pkgs; });
+}