I was under the impression that even today, most code is written in an object-oriented style (or at least, written in languages that support OOP). Therefore, most languages support subtyping via inheritance. Is that not true?
Whoa there - those are very different claims! Most modern languages are multi-paradigm. You can write Python in an OO way, or a data oriented way, or a functional way, or whatever you like. The same is true of JavaScript/typescript. And modern Java. And lots of languages.
Just because the language has the class keyword doesn’t mean everything can be subtyped. If you have an entity-component system, you can’t necessarily inherit from your Entity type. Likewise I can’t inherit from a react component, just because JavaScript has classes. (At least not using modern react)
Modern Java is still very definitely OOP and not multi-paradigm. Other JVM languages, like Scala or Kotlin, add more multi-paradigm features to that ecosystem, but modern Java doesn't.
And you can’t subtype those.
Other JVM languages, like scala, are more OO than Java.
I was pretty surprised and impressed to see a modern example lately. There’s Record data types, stronger type inference with `var`, pretty great structural pattern matching, switch expressions (that return a value), stream apis for map, filter, and reduce etc. All of these move it further away from strictly OOP.
And separate but still cool is a pretty neat virtual thread system too. Java has definitely had a bit of a glow up since I learned it in uni.
I suspect that the stronger claim is true - but even the weaker claim would invalidate the article's statements that "existing programming languages have little or no subtyping" and that OOP was a "fad" and has been left in the past.
> , “subtyping” might call to mind classes and inheritance hierarchies. However, subtyping is a far more basic and general notion than that.
Yes, there are other forms of subtyping, but saying that many languages don't have subtyping just because they don't have these other forms of subtyping is either cluelessness or satire.