Something like this would require parsing the JS code to extract function signatures - we’d need to somehow detect that there’s a greet function with one parameter defined inside the sigil and automatically generate the corresponding Elixir bindings. Not sure it’s worth the hassle…
It might make sense for non-function code fragments, but then you’re mixing JS and Elixir code in ways that could get confusing - especially for debugging and tooling support.
This approach would be for power-users building interop libraries. Most developers could just use exported JS functions through FFI or event listeners and call them from Hologram.
I’m not sure about using Hologram.put_action since put_action/3 in components/pages does something a little different - it modifies the struct in place and has a different set of parameters. It might be confusing to reuse the same name for what’s essentially a different operation (dispatching from JS vs modifying component struct).
I think we should generally use JS conventions when inside JS code.
Thanks for all the feedback though - really helpful for thinking through these design decisions! 
(he worked with Elm ports in the past).
