1. Healthcare
Fall 2017, I started integrating Elm into an AngularJS application after experimenting with it on a couple of side projects. After a successful initial feature, I convinced the team to use it for new features. Another couple of developers helped to create the initial version until late 2018. We started in Elm 0.18 and converted it to 0.19. Now a sole part-time college student maintains and adds new features to it.
2. Transportation management
Since January 2019, I work on an Elm project, once again weaved into an existing AngularJS app, with ~34k lines of Elm code. I inherited it with no interaction from the previous developer. It looks like it was introduced in mid-2017 and is currently on Elm 0.19. Although it is not perfect, not always following best practices, it is much easier to maintain than anything I've worked on in the past. On JS apps, I've torn my hair out trying to figure out what is going on and attempting to add new features.
With Elm, I refactor daringly and rest more easily.
Please let me know if you have any specific questions.