===> Compiling p1_utils
===> Compiling fast_xml
==> hedwig_xmpp
Compiling 1 file (.ex)
== Compilation error on file lib/hedwig_xmpp.ex ==
** (CompileError) lib/hedwig_xmpp.ex:4: module Hedwig.Adapter is not loaded and could not be found
(elixir) expanding macro: Kernel.use/1
lib/hedwig_xmpp.ex:4: Hedwig.Adapters.XMPP (module)
(elixir) lib/kernel/parallel_compiler.ex:116: anonymous fn/4 in Kernel.ParallelCompiler.spawn_compilers/1
could not compile dependency :hedwig_xmpp, "mix compile" failed. You can recompile this dependency with "mix deps.compile hedwig_xmpp", update it with "mix deps.update hedwig_xmpp" or clean it with "mix deps.clean hedwig_xmpp"
OS X 10.11.6 elixir 1.3.2 Erlang/OTP R19
Also failed with elixir 1.2.5/OTP R18.