We weren't bit by the removal of native/kernel code, but it definitely turned a lot of people away that may have been committed to Elm before.
We also ported our Elm codebase from 0.18 to 0.19. It took us almost a week working almost 24/7 across two timezones to make the damn thing compile again. Did not see the UI for the entire week, but once it compiled it (mostly) just worked like nothing had changed (that's after 429 files changed, 16422 insertions(+), 12116 deletions(-)).
My colleague took notes of the progress at https://gist.github.com/mordrax/efcd34739ed56bb64d2b12d2401b...
> We have until Friday 7th September to upgrade to Elm 0.19.
I'm completely ignorant about the transition, but I'm curious what the source of this deadline was. Would you mind expanding?
At our company it was much less drastic. At the time we had about 35kloc of Elm and it took me one evening of Vim macro frenzy. The trickiest things we encountered were an elm/http API change and temporarily vendoring packages that didn't yet upgrade themselves.