It's the kind of thing that even if you don't end up using, you come out with lessons that make you a better programmer. Some that I remember:
- The compiler was fast, it made me aware that you could have an iterative workflow like most dynamic languages but driven by types
- The language/framework constructs (views, updates, etc) made it clear what kind of functionality had to live where so it makes me aware to define roles/arch in React apps that are 'just components'
- Error messages are just awesome, it was the clearest I had seen at that point and made me realize other languages just haven't paid enough attention to make them more usable