Guix Goals: One Hackable Developer Tool To Rule Them All

[jgart]

Hi Guixers,

What do you think if we were to implement "Guix Goals"?

The various language ecosystems have their own linters, formatters,
typecheckers, repls, test runners, etc.

What if Guix could manage them all?

`guix lint` in a python project would run mypy.
`guix lint` in a haskell project would run hlint.
`guix lint` in an erlang project would run dialyzer.

`guix fmt` in a python project would run black.
`guix fmt` in a haskell project would run ormolu.
`guix fmt` in a erlang project would run erlfmt.

`guix repl` in a python project would run ptpython or some other configured 
repl.
`guix repl` in a haskell project would run ghci.
`guix repl` in a erlang project would run erl.

`guix test` in a python project would run pytest or unittest.
`guix test` in a haskell project would run hunit.
`guix test` in a erlang project would run eunit.

`guix run` in a python project could start a flask app listening on a 
particular port.
`guix run` in a ruby project could start a puma server.
`guix run` in a haskell project could run a pre-configured script or Main.hs
`guix run` in a erlang project could start a cowboy server.

The idea would be to have Guix provide a configurable CLI wrapper
subcommand around all language ecosystem developer tools. In other words
it's the same Guixy thesis applied to developer tooling. I think this
could take the Guix developer experience to the next level.