attempted workaround

Code.require_file "my_iex_helpers.exs"
import MyIExHelpers

λ iex
...
Error while evaluating: /Users/alco/tmp/.iex.exs
** (CompileError) .iex.exs:2: module MyIExHelpers is not loaded and could not be found
    (elixir) src/elixir_exp.erl:123: :elixir_exp.expand/2
    (stdlib) lists.erl:1352: :lists.mapfoldl/3
    (stdlib) lists.erl:1353: :lists.mapfoldl/3
    (elixir) src/elixir_exp.erl:49: :elixir_exp.expand/2

original issue

defmodule MyIExHelpers do
  def s do :init.stop end
end

import MyIExHelpers


λ iex
...
Error while evaluating: /Users/alco/tmp/.iex.exs
** (CompileError) .iex.exs:5: module MyIExHelpers is not loaded but was defined. This happens because you are trying to use a module in the same context it is defined. Try defining the module outside the context that requires it.
    (elixir) src/elixir_exp.erl:123: :elixir_exp.expand/2
    (stdlib) lists.erl:1352: :lists.mapfoldl/3
    (stdlib) lists.erl:1353: :lists.mapfoldl/3
    (elixir) src/elixir_exp.erl:49: :elixir_exp.expand/2