From `guix package --help`

--8<---------------cut here---------------start------------->8---
  -f, --install-from-file=FILE
                         install the package that the code within FILE
                         evaluates to
--8<---------------cut here---------------end--------------->8---

In your file, the last top-level expression
is not a package, so `guix package --install-from-file=FILE` does nothing.

Add this last line

--8<---------------cut here---------------start------------->8---
doses
--8<---------------cut here---------------end--------------->8---

and you should be good to go!

-- 
Pierre Neidhardt
https://ambrevar.xyz/