6 ms·

> lets not forget that the Go team made the same blunder made by Java To be fair, they were working on parametric polymorphism since the beginning. There are c

by 9rx 1y ago

> lets not forget that the Go team made the same blunder made by Java To be fair, they were working on parametric polymorphism since the beginning. There are countless public proposals, and many more that never made it beyond the walls of Google. Problem was that they struggled to find a design that didn't make the same blunder as Java. I'm sure it would have been easy to add Java-style generics early on, but... yikes. Even the Java team themselves warned the Go team to not make that mistake.

karmakaze 1y ago
At least Java supports covariance and contravariance where Go only supports invariant generics.
- PaulHoule 1y ago
  Java has evolved to contain much of “ML the good parts” such as that languages like Kotlin or Scala that offer a chance to be just a bit better in the JVM look less necessary
  - throwaway2037 1y ago
    > Java has evolved to contain much of “ML the good parts” Can you give some examples?
    - yz453 1y ago
      Not OP. IMO the recent Java changes, including pattern matching (especially when using along with sealed interface), virtual threads (and structured concurrency on the way), string templates, are all very solid additions to the language. Using these new features one can write very expressive modern code while still being interoperable with the Java 8 dependency someone at their company wrote 20 years ago.
      - tpm 1y ago
        fyi: string templates were just a preview and removed in Java 23
        PaulHoule 1y ago
        For Java systems that I work on for my own account there is a lot of stuffing things like SQL queries into resource files so that I don't have to mess around with quotes and such.
    - PaulHoule 1y ago
      Like a lot of other languages, Java has gotten a big dose of https://en.wikipedia.org/wiki/Hindley%E2%80%93Milner_type_system https://en.wikipedia.org/wiki/Hindley%E2%80%93Milner_type_sy... To defy it's reputation for verbosity, Java's lambda syntax is both terse and highly flexible. Sum and product types are possible with records and sealed classes. Pattern matching.
      - karmakaze 1y ago
        I even found a way to make ad-hoc union types of element types from other packages that does exhaustive switch/case checking. I quickly wrote down a PoC so I wouldn't forget[0]. It needs wrapper types and sealed interfaces in the consuming app/package but is manageable and turned out better than other attempts I'd made. [0] https://github.com/karmakaze/AdHocUnion https://github.com/karmakaze/AdHocUnion
throwaway2037 1y ago
> blunder made by Java For normies, what is wrong with Java generics? (Do the same complaints apply to C# generics?) I came from C++ to Java, and I found Java generics pretty easy to use. I'm not interested in what "PL (programming language) people" have to say about it. They dislike all generic/parametric polymorphism implementations except their pet language that no one uses. I'm interested in practical things that work and are easy for normies to learn and use well. > Even the Java team themselves warned the Go team to not make that mistake. Do you have a source for that?
- moomin 1y ago
  Yeah, it _doesn’t_ apply to C# generics. Basically, if you’ve got List<Person> and List<Company> in C#, those are different classes. In Java, there’s only one class that’s polymorphic. This causes a surprising number of restrictions: https://docs.oracle.com/javase/tutorial/java/generics/restrictions.html https://docs.oracle.com/javase/tutorial/java/generics/restri...
- gr_norm 1y ago
  > I'm not interested in what "PL (programming language) people" have to say about it. They dislike all generic/parametric polymorphism implementations except their pet language that no one uses. That's strange. I seem to recall the PL community invented the generics system for Java [0,1]. Actually, I'm pretty sure Philip Wadler had to show them how to work out contravariance correctly. And topically to this thread, Rob Pike asked for his help again designing the generics system for Go [2,3]. A number of mistakes under consideration were curtailed as a result, detailed in that LWN article. There are countless other examples, so can you elaborate on what you're talking about? Because essentially all meaningful progress on programming languages (yes, including the ones you use) was achieved, or at least fundamentally enabled, by "PL people". [0] https://homepages.inf.ed.ac.uk/wadler/gj/ https://homepages.inf.ed.ac.uk/wadler/gj/ [1] https://homepages.inf.ed.ac.uk/wadler/gj/Documents/gj-oopsla.pdf https://homepages.inf.ed.ac.uk/wadler/gj/Documents/gj-oopsla... [2] https://arxiv.org/pdf/2005.11710 https://arxiv.org/pdf/2005.11710 [3] https://lwn.net/Articles/824716/ https://lwn.net/Articles/824716/
- tpm 1y ago
pjmlp 1y ago
Should I repost the blog posts where they acknowledge the failure to look into languages like CLU?

by 9rx 1y ago

karmakaze 1y ago

At least Java supports covariance and contravariance where Go only supports invariant generics.

PaulHoule 1y ago
Java has evolved to contain much of “ML the good parts” such as that languages like Kotlin or Scala that offer a chance to be just a bit better in the JVM look less necessary
- throwaway2037 1y ago
  > Java has evolved to contain much of “ML the good parts” Can you give some examples?
  - yz453 1y ago
    Not OP. IMO the recent Java changes, including pattern matching (especially when using along with sealed interface), virtual threads (and structured concurrency on the way), string templates, are all very solid additions to the language. Using these new features one can write very expressive modern code while still being interoperable with the Java 8 dependency someone at their company wrote 20 years ago.
    - tpm 1y ago
      fyi: string templates were just a preview and removed in Java 23
      - PaulHoule 1y ago
        For Java systems that I work on for my own account there is a lot of stuffing things like SQL queries into resource files so that I don't have to mess around with quotes and such.
  - PaulHoule 1y ago
    Like a lot of other languages, Java has gotten a big dose of https://en.wikipedia.org/wiki/Hindley%E2%80%93Milner_type_system https://en.wikipedia.org/wiki/Hindley%E2%80%93Milner_type_sy... To defy it's reputation for verbosity, Java's lambda syntax is both terse and highly flexible. Sum and product types are possible with records and sealed classes. Pattern matching.
    - karmakaze 1y ago
      I even found a way to make ad-hoc union types of element types from other packages that does exhaustive switch/case checking. I quickly wrote down a PoC so I wouldn't forget[0]. It needs wrapper types and sealed interfaces in the consuming app/package but is manageable and turned out better than other attempts I'd made. [0] https://github.com/karmakaze/AdHocUnion https://github.com/karmakaze/AdHocUnion

throwaway2037 1y ago

> blunder made by Java For normies, what is wrong with Java generics? (Do the same complaints apply to C# generics?) I came from C++ to Java, and I found Java generics pretty easy to use. I'm not interested in what "PL (programming language) people" have to say about it. They dislike all generic/parametric polymorphism implementations except their pet language that no one uses. I'm interested in practical things that work and are easy for normies to learn and use well. > Even the Java team themselves warned the Go team to not make that mistake. Do you have a source for that?

moomin 1y ago
Yeah, it _doesn’t_ apply to C# generics. Basically, if you’ve got List<Person> and List<Company> in C#, those are different classes. In Java, there’s only one class that’s polymorphic. This causes a surprising number of restrictions: https://docs.oracle.com/javase/tutorial/java/generics/restrictions.html https://docs.oracle.com/javase/tutorial/java/generics/restri...
gr_norm 1y ago
> I'm not interested in what "PL (programming language) people" have to say about it. They dislike all generic/parametric polymorphism implementations except their pet language that no one uses. That's strange. I seem to recall the PL community invented the generics system for Java [0,1]. Actually, I'm pretty sure Philip Wadler had to show them how to work out contravariance correctly. And topically to this thread, Rob Pike asked for his help again designing the generics system for Go [2,3]. A number of mistakes under consideration were curtailed as a result, detailed in that LWN article. There are countless other examples, so can you elaborate on what you're talking about? Because essentially all meaningful progress on programming languages (yes, including the ones you use) was achieved, or at least fundamentally enabled, by "PL people". [0] https://homepages.inf.ed.ac.uk/wadler/gj/ https://homepages.inf.ed.ac.uk/wadler/gj/ [1] https://homepages.inf.ed.ac.uk/wadler/gj/Documents/gj-oopsla.pdf https://homepages.inf.ed.ac.uk/wadler/gj/Documents/gj-oopsla... [2] https://arxiv.org/pdf/2005.11710 https://arxiv.org/pdf/2005.11710 [3] https://lwn.net/Articles/824716/ https://lwn.net/Articles/824716/
tpm 1y ago

pjmlp 1y ago

Should I repost the blog posts where they acknowledge the failure to look into languages like CLU?