defmodule Foo do
  def setup(funcs) do
    Code.compile_quoted(quote bind_quoted: [funcs: funcs] do
      defmodule RuntimeLookup do
        for {name, value} <- funcs, do: def unquote(name)(), do: unquote(value)
      end
    end)
  end

  def main do
    setup(foo: 42)

    IO.inspect RuntimeLookup.foo()
  end
end

Foo.main