Especially anything related to lambdas, map, filter and co.
Something that was lost in most OOP languages that followed suit, until like a decade later.
Good point. And both Java and Ruby borrowed from Smalltalk (according to Wikipedia Kotlin does not, but that is: not directly.
Sadly Java did not take Smalltalk's FP inspiration (I guess they were strayed by C++'s lead in that regard), and we needed streams and now Kotlin to fix that :)
Smalltalk's syntax never go really popular though. One could say that was its biggest drawback.
A lot of Smalltalk-style syntax was absolutely massive for a decade or so you could argue, at least under the guise of the gazillions of iPhone apps that were written in Objective-C. This random blog post probably does a better job than me:
> https://richardeng.medium.com/apple-has-been-using-smalltalk...
This would be my guess, I always heard nice things about it and liked many concepts, but the syntax was just plain ugly to me, so I never felt the urge to try it out. I imagine others felt similar.