My experience with Elm was that it's very elegant and fun to work with if you are building a purely clientside application, but once you need communication with server the APIs are not very well developed and it becomes a major headache.
Note that none of the examples in this page (or in any Elm tutorial I found) flesh out interaction with a backend.
Note that none of the examples in this page (or in any Elm tutorial I found) flesh out interaction with a backend.