Since upgrading to Elixir 1.1 and Eralang 18, I'm noticing that Dialyzer has some issues with String interpolation. This Gist demonstrates an issue with EEx templates that map over a list of Strings

bad_template.eex

<%= Enum.map arbitrary_list, fn(item) -> %>
 <%= item %>
<%= end %>

dialyzer_warning

bad_template.eex:5: Guard test is_binary(_@2::[any()]) can never succeed

scaffold.ex

defmodule Scaffold do

  require EEx

  EEx.function_from_file(
    :def,
    :bad_template,
    Path.expand("bad_template.eex", "lib/templates"),
    [:arbitrary_list]
  )

  def build do
    template = bad_template(["foo", "bar"])
  end
end