Rscons::Environment.new do |env|
  env.build_root = "build"
  env.add_builder(:Checker) do |target, sources, cache, env, vars|
    unless cache.up_to_date?(target, :Checker, sources, env)
      puts "Checker #{sources.first}" if env.echo != :off
      cache.register_build(target, :Checker, sources, env)
    end
    target
  end
  env.Program("simple.exe", "simple.c")
  env.Checker(:checker, "simple.exe")
end