Row polymorphism and algebraic data types if we want to talk about things Dart does not have, with an enormous ecosystem at your disposition.
If we want to prioritize a sound type system, why then go for a language that is for the most part Java but with no ecosystem, instead of something like Reason/OCaml, Haskell, PureScript which absolutely blow Dart out of the water as languages; or even if your number one priority is targeting Java devs with something more palatable, why not Kotlin even?
Why give artificial life to a language that was on its deathbed and brings absolutely nothing useful to the ecosystem yet will contribute to the amount of churn suffered in the industry?
Dart team is already working on some nice additions to the language. If ADTs are something many community members are looking for, I'm pretty sure it'll be added.
> and brings absolutely nothing useful
Dart is a language that's predictable (no WATs), performant, has the best built-in tooling to facilitate quick iterative development, the best package manager and can be used to build web, mobile and desktop apps with high level of shared codebase between them.
It's not the best language by any means but it's already a good language. And it's getting better and better.
Well that is a non-answer on every front. Of course, if devs start pouring effort into Dart it will get an ecosystem; but why would I want to when Dart offers nothing over other languages?
And yes, we can submit feature requests, and the language authors may and may not add them. I'd rather go for a language that further aligns with the expectations of a modern language from the start rather than plead with the authors to turn it into something it's not.
> Dart is a language that's predictable (no WATs),
Ok, so it beats the raw JS with no dev tooling development experience. That's the bare minimum.
> performant
Plenty of performant languages to go around, including many more performant ones.
> has the best built-in tooling to facilitate quick iterative development
What does it bring over any other language with a semi-decent REPL?
> the best package manager
You'll have to expand on this, it's a very bold claim.
> and can be used to build web, mobile and desktop apps with high level of shared codebase between them.
So can any compile to JS language, Kotlin, C#, Clojure, among others, and since you place so little value on ecosystem I'll throw a special mention to Idris in too, which can compile to performant JS, the JVM (no bridge necessary on Android), C (usable on iOS) and pretty much whatever; and almost guaranteed blows any other language you can name out of the water when it comes to modern features and being pragmatic.