Code generators like RATFOR, lex, yacc, and the C preprocessor? I think it’s fair to say that those are well understood. Generics like Ada Generics, C++ templates, and Java Generics? I think it’s fair to say that we are only beginning to understand the benefits and drawbacks of that approach to code generation, which is why every time I recompile the Java application I’m currently working on, I get erroneous warnings telling my that my varargs are causing heap pollution in my generic static methods. (Which I can suppress, but instead I’m planning to delete those methods.)
Even OCaml, whose approach to parametric polymorphism is worlds simpler than any of the monstrosities mentioned above, just changed its approach by adding GADTs, which I still don’t understand fully despite the best efforts of generous HN commenters.
So I think that, given that Golang/Issue9 decided not to include inheritance, linear types, exceptions, or overloading (even of operators!), in large part because they aren’t well-understood, it’s entirely unsurprising that it decided not to include generics, either.
> Code generators like RATFOR, lex, yacc, and the C preprocessor? I think it’s fair to say that those are well understood.
Yes, that is exactly what I said in the post you are responding to.
> I think it’s fair to say that we are only beginning to understand the benefits and drawbacks of that approach to code generation, which is why every time I recompile the Java application I’m currently working on, I get erroneous warnings telling my that my varargs are causing heap pollution in my generic static methods. (Which I can suppress, but instead I’m planning to delete those methods.)
Just because you don't understand something, doesn't mean that nobody does?
I guess you didn't understand the problem I was describing. I wasn't saying that the problem is that I don't understand parametric polymorphism, or for that matter its realization via code generation, although I’m sure e.g. Philip Wadler understands those things a whole heck of a lot better than I do. The problem was that the Java language designers didn't understand generics, and accidentally implemented varargs in 1.5 in a way that produced a completely unnecessary and avoidable collision with the parametric polymorphism system (designed by Wadler) that they also introduced in 1.5. And there are a variety of similar problems in various parametric-polymorphism systems, which leads me to think that the problem is not merely that some loser at Sun didn't understand these things (and didn't bother to ask Wadler, who surely could have warned him off the particular stupidity I mentioned) but rather that there is a general lack of understanding of parametric polymorphism.
Even OCaml, whose approach to parametric polymorphism is worlds simpler than any of the monstrosities mentioned above, just changed its approach by adding GADTs, which I still don’t understand fully despite the best efforts of generous HN commenters.
So I think that, given that Golang/Issue9 decided not to include inheritance, linear types, exceptions, or overloading (even of operators!), in large part because they aren’t well-understood, it’s entirely unsurprising that it decided not to include generics, either.