That isn't to say the designers of JavaScript and C# don't think carefully about the addition of new features; indeed, was it Anders Heljsberg who made the point about all new proposed features starting with negative points?
But Java's recent and upcoming additions show _taste_: adopting a single lambda notation that fitted smoothly with the surrounding class-based OOP paradigm via SAM types (rather than magically-generated-type-style lambdas succeeding two overlapping "delegate"/"event"-like features); implementing (sadly somewhat-incompatible) modules that can curtail unbounded reflection, opening the door to greater reasonability and performance in the future; proposing Project Loom to avoid the async/sync API split that hit Python, C#, and even Kotlin Coroutines; and now Valhalla, which was quietly mulled on for years before arriving at this very reasonable solution that considers myriad angles.
I like this approach to language design and think it bodes well for the language's future. It's a sweet spot between being necessarily conservative, dealing with developers' real-world problems, and giving time to mull over new language feature designs and not just implementing as soon (and haphazardly) as possible to please vocal developers.
It's implemented features Java had just gotten much earlier, in much more useful forms (see: generics, lambdas) without them being "haphazard" about it.
-
To me tasteful is what C# did, breaking changes when needed, but only when so much value was added no one could be upset with the result.
It takes way more effort, and way more carefulness than "we're going to move at glacial pace and provide half-hearted features in the name of backwards compatibility" (again, see: lambdas and generics)
Since Java was introduced in 1995 until today, Microsoft's software framework has had about three or four drastic backward-incompatible "generations", depending how you count. Most Java code written in 1995 will run, with little or no change, on the current JDK 13, and would compile on JDK 13 with only minor changes.
Leaving aside the JDK 7 years (2006-2011) when Sun was struggling and then going through an acquisition, the rate of innovation on the Java platform is quite high. It's just that we emphasize other parts of the platform more than the Java language because that's where Java has always believed most of the value is. In the past five years Java has seen an exceptional new low-overhead, extendable profiling capability (JFR), groundbreaking new GCs (ZGC), and what is probably the biggest breakthrough in compilation technology of the past decade (Graal). Those are all huge developments, none of them affecting the frontend language in any way. An innovative, state-of-the-art runtime programmed with an intentionally conservative language has been Java's strategy from the beginning -- James Gosling called it a wolf in sheep's clothing (https://youtu.be/Dq2WQuWVrgQ) -- and it has worked quite well. One could argue that that's the only way to sell a wolf to such an industry. Indeed, despite some grumblings on HN, it seems like most software developers prefer it this way.
* Too many overlapping concepts for referring to code by value and defining them inline: events, delegates, anonymous delegates, and lambdas.
* Lambdas that generate magic types rather than slotting into SAM types. This works great for functional languages, sure, but doesn't fit well into a class-based OOP language.
* `ref` and `out` parameters to appease archaic COM APIs.
* Tuple unpacking, which makes sense independently but then bizzarely tries to integrate with `out` parameters.
* A nice "ex nihlo" object literal syntax that shoots itself in the foot by undermining immutability due to requiring settable fields. (TBF, later versions fixed this IIRC.)
* Inline functions in methods in a language that already has lambdas and methods; it's just bloat.
* `as` casting that yields nulls. Did it really need a whole new syntax just to handle null more concisely specifically for casting?
* `partial` classes. Encouraging even more code generation with features like this is a questionable idea and wasn't necessary in other languages.
* `dynamic`. Even if there are use cases for it, it's strange in an otherwise static language with a top-level Object type anyway. I'm saying this as someone who's perfectly happy with fully dynamic languages like Erlang and Lisp. I just don't see the point of adding it to C# specifically.
* C-style enumerations.
* Properties. Invoking side-effects on something that is syntactically indistinguishable from an attribute read is a bad idea. Auto-generation of Java's verbose getters would be long overdue, but the caller site shouldn't be the same a la C#.
* Extension methods. It seems quite ad hoc compared to static addition of types to common operations in other languages, like imported traits in Rust or typeclasses in Haskell.
* Proposed "shapes". Looks like a good idea by itself but will overlap too much with default method implementation and other existing mechanisms.
* Interfaces prefixed with `I`. Not strictly a language problem but an ecosystem one. I shouldn't need to know what _sort_ of type I'm dealing with, that's '90s Hungarian notation.
* Nullable reference types. Getting rid of null is good, but this proposal became confusing. They mentioned opting in assembly-wide for a while but there was then a conversation about having it just warn in some cases. I need to read the latest literature around this, but it seemed less elegant than Java just adding a monad-like Optional type and not adding loads of special-case operations with question marks everywhere.
Despite this, I still admire a lot of the design decisions behind C#. LINQ was great. `async/await`, despite my belief of its inferiority to Goroutines/Project Loom/Erlang processes, was still a great innovation from Midiori at the time. Value types were obviously right to be implemented early on. Assemblies were a good idea. Private by default rather than package-accessibility was a nice touch, as was the `override` keyword. The C# team are smart people who know what they are doing!
As an aside, I used to be firmly against erased generics, but reading more about the tradeoffs from the likes of Gilad Bracha has caused me to reconsider.
Wait, why do we care about the JVM?? This whole article appears to address concerns that, while fundamental to programming, are also fundamentally irrelevant to shipping products.
Well, to be fair, it's more like there are two (or so) good cross platform ones at the moment, but there isn't one so popular to be de facto. And there isn't one that is standard.
Besides, the most popular packaging and distribution systems for native code might still be the popular Linux distros. Packaging and distributing precompiled binaries with native ABIs (not targeting interpreters or runtimes) is much more complicated. Folks have decided to value other things than portability of packages for now. That could change in the future.
The biggest impact of the 5 years for working developers has probably been:
* Streaming API and lambdas allowing usual `map`/`filter`/`reduce` transformation pipelines line many other languages (lazy, unlike JS's `Array` methods, parallelism considered via "spliterators" unlike Python).
* Default methods in interfaces, _not_ making them traits, but arguably more "trait-like". It allowed them to add many useful methods onto existing types without needing bifurcate the common APIs.
* A REPL. Probably not a big deal for a professional developer, who likely uses IntelliJ's "Evaluate Expression" feature already for a similar feature, but pretty useful for education I guess.
* Better at being stuffed inside Docker containers with resource limits. Also, max permgen space no longer a problem really (it's where you had to set an upper memory limit when invoking Java programs, which was annoying). Just generally less annoying at being deployed in modern infrasructures.
* APIs like `File.lines` that mean you don't need to recite War and Peace just to do a buffered operation across lines in a file. Generally more ergonomic APIs that finally make basic operations sane.
* Type inference with `var`. Basically the same as C#'s `var` or Go's `:=`.
* More native executable-producing tooling. jlink, jpackager, etc. The dream of ubiquitous, shared Java runtimes installed everywhere didn't really work out, and they seem to have realised that.
* Ecosystem moving away from XML. Still there, just less common. Runtime annotations are used more heavily, which I'm honestly not sure is a massive improvement. Hopefully more lambda-heavy APIs will reduce use of runtime annotations; see Spring WebFlux's functional handlers for annotation-based controllers for a comparison.
There's a lot more, but I'd argue it won't be as immediately visible for the working developer more than those points. Modules were important for the ecosystem, but most devs probably aren't worrying about that day-to-day. Gradle and Maven still dominate the building/packaging side.
But even faster is just looking through the release notes for the major versions.
There is really no good excuse. Many developers have abandoned java due to the glacial progress with both the language and the VM. It is legacy now.
The main benefit (IMO) of Vahala would be for other JVM languages (such as Kotlin) to make the implementation of value types more efficient.
(I use both CLR and JVM in my work, but is clear to me that the CLR is superior on many fronts).
Not being sarcastic.
https://github.com/Kotlin/KEEP/pull/87
If if that does not succeed, the Arrow folks are working on a meta compiler (think template Haskell but with IDE support) that should get you HKTs and union types.
https://github.com/arrow-kt/arrow-meta
Regardless, something quite close to HKTs is available today via type level defunctionalisation. Just look at the Arrow docs
I would much rather some native syntax like K<T> where K is some generic though.
Does this mean that the value of these additions are partially diminished because of spectre and meltdown vulnerability fixes?
This is nothing to do with specular execution.
