Dear Guix ,

please consider the attached guix.scm. If you try to build it you will 
notice many messages as the following:

  warning: :telemetry.execute/3 is undefined (module :telemetry is not available or is yet to be defined)


until the build fails with:

16:26:55.642 [notice] Application eex exited: :stopped
** (Mix) Could not start application telemetry: could not find application file: telemetry.app
error: in phase 'check': uncaught exception:
%exception #<&invoke-error program: "mix" arguments: ("do" "compile" "--no-deps-check" "--no-prune-code-paths" "+" "test" "--no-deps-check") exit-status: 1 term-signal: #f stop-signal: #f>
phase `check' failed after 0.4 seconds
command "mix" "do" "compile" "--no-deps-check" "--no-prune-code-paths" "+" "test" "--no-deps-check" failed with status 1
build process 18 exited with status 256




This is because Erlang dependencies are not made available to Elixir 
builds. I'm sending a patch addressing this issue.


Thank you for your work,


giacomo