> In other words, is there something specific about Rust's sum types that one is after in this example? Or just the concept of sum types.
I think, concretely, it's the fact that Rust's syntax is more intuitive to the average engineer than ML or Haskell. Maybe that's a failure of SWE education! But generally speaking, it's easier to explain what Rust does to someone who has taken a year or two of Java, C, or C++ than to explain ML to them.
I agree and think you're right, to a point. But I would posit that a much higher percentage of devs than the typical HNer would expect would find the Rust syntax to be pretty arcane. Although I grant that they'd find Haskell to be *more* arcane for sure.
And that stopping point I think is where the perception of Rust's popularity on sites like HN is much higher than in the general public. And by that I mean people who at least grok, if not use, Rust and not people who like the idea of Rust.
For instance, keep in mind that even during the heyday of Scala here on HN the rest of the JVM world was complaining that Scala syntax was too arcane.
I think, concretely, it's the fact that Rust's syntax is more intuitive to the average engineer than ML or Haskell. Maybe that's a failure of SWE education! But generally speaking, it's easier to explain what Rust does to someone who has taken a year or two of Java, C, or C++ than to explain ML to them.