Many of the ideas expressed here may feel like bells and whistles but tend to have a formal backing which makes them quite a bit different than other language f

Many of the ideas expressed here may feel like bells and whistles but tend to have a formal backing which makes them quite a bit different than other language features. They might still impact UI in a way that's highly undesirable, but they're less-than-average likely to be leaky abstractions or gotchas. Typically, I feel these sorts of ideas appeal to simpler foundations and achieve richness through rich additions to a simple foundation that can be shown to be consistent and compatible with that foundation in a thorough (proven) way. It's just a different ballgame. Although, again, UI is another issue.