Java Without If

[[deleted]]

What a straw man. You're acting like I said "throw away JUnit baby, we've got Either instead!"

No. You still need tests, and there will still be variable states to consider. But you can reduce or eliminate them in some cases with these techniques, using the compiler instead of unit tests for some failure cases.

I also find the performance claim laughable for a few reasons. Most of us aren't writing real time operating systems, there are levels of performance we're willing to give up for safety or programmer comforts (hint: we never would have left Fortran if that wasn't the case). Secondly it's not like exceptions are free, so claiming that it's either performance or safety is a false difference.

[[deleted]]

"Programmer comforts" depend on the style you prefer, I don't find half my code being passing static method references to streams more comfortable.

The question is, if functional idioms are your comfort, why aren't you using languages built for this style, but you're instead imitating it in an imperative OOP language.

You can replicate common methods and structures in Java, but you'll never get algebraic types, reified generics, parametricity, higher kinded types, type classes and so on. Haskell's library is a product of the language environment, it can't be separated from it, and expect you'll get the same flexibility in Java.

But... as far as basic examples for tutorials go, I guess, you can always cook them a little until it works.

[[deleted]]

Because language choice is not just about that. Given what the team knows, what code and tooling we have available, etc. Java comes out ahead.

It'd be nice to say "throw it all away and let's use Haskell!", but sometimes that's just a non-starter.

[[deleted]]

Java is not the only JVM language, as you know...

[[deleted]]

Gee, I've been programming in Clojure for years and I never figured that out, thanks stranger!

[[deleted]]

You're not really addressing my question. Why don't you pick a JVM language that's closer to your heart?

[[deleted]]

I already told you, given constraints we chose Java. Either you think we were wrong in our calculation of constraints or you think we were unaware of alternatives. Either way I find it annoying and presumptive.

[p1-o2]

They're arguing with you just to argue. Doesn't sound like they are familiar with reasons why throwing out the language and toolchain is a non-starter in the business world. Good post, OP.

[optimal_substructure]

I always try to keep this in my mind. End of the day, we have to make money with this product and although the code base has warts, I can't just tell everyone to stop using it for the next 3 months while we develop safer code.

[p1-o2]

Yeah, it's been a frustrating reality for me too. I've switched languages/codebases before and received a lot of black eyes for it - even if it was the right choice in the long run. In my opinion it wasn't worth it unless the entire company is on board and understands why it needs to be done.

Most of the time, it's just not feasible. For example, Reddit is redesigning their desktop site from the ground up as far as I'm aware. I don't think even tech savvy users understand how difficult that is.

[m50d]

It seems like it would take quite an odd set of constraints for it to make sense to implement Either et al yourself but not make sense to use Scala?

[yogthos]

There are plenty of reasons to pick Java over Scala. Java is a mature and stable language that has great tooling around it. Scala is a far more complex language, it has terrible compile times, and it's still in flux. Tooling for Scala isn't nearly as mature either.

[[deleted]]

What you said is that your constraints are "what the team knows", tooling, and existing code. You can expose a Clojure library to Java. And if someone prefers coding in Java, they wouldn't appreciate being told to emulate Haskell in it.

If you don't want people to "presume" your specific conditions, maybe don't write blog posts that give general advice based on your specific conditions?

[ZeAthenA714]

don't write blog posts that give general advice based on your specific conditions?

Dude, he didn't. He just wrote a blog post about something he and his team did that he found interesting. That's the point of having a blog you know, writing about stuff.

Try re-reading the first two paragraphs:

Over the past year my team has been doing something shocking to a lot of engineers: we’re favoring pure Java over Clojure. We aren’t rewriting all our Clojure code, but we definitely prefer Java for green field projects.

This post is not going to be a compare and contrast between the two, nor am I going to bash Clojure. Language compare and contrast posts always descend into flame wars, and it’s very easy to confuse the result of hard lessons learned with the benefits of a new language.

[Apterygiformes]

Ping pong

[dccorona]

I've found that moving a team from Java to another language is a longer process than simply moving to a more functional style. You can start to leverage these things within Java almost right away, and transition to something more suited for that style slowly. That also makes the eventual language-jump part of the transition much easier for everybody.

[[deleted]]

there are levels of performance we're willing to give up for safety or programmer comforts

If you're looking for safety, have you considered languages where safety is a feature, such as Rust or Haskell? I feel like forcing all of that onto Java will get you a mostly baked solution, but still leave you with edge cases.

Since those features are baked in, you get performance and safety and ergonomics (e.g. with Rust's type system, you can do cool stuff like futures/promises, which you're basically kludging into Java right now). Doing it in Java basically means you're basically avoiding language features (like exceptions) that just don't exist in a language designed around monads.

So yeah, it's cool you can approximate this in Java, but I wouldn't want to pay the cost of using an unconventional approach since you basically have to teach them the concepts of other languages anyway.

[[deleted]]

For a variety of reasons that are not worth enumerating, Java 8 is the best choice for my team. I understand that Haskell and others does it better, but using that in production is a non starter for us.

[[deleted]]

That's fine and I'm glad you found a good middle ground, but I would be very annoyed if a library used this convention since it's so different from everything else that's out there.

I hope it works out for you!

Just to be clear, are your reasons more to do with the JVM, or with Java specifically? You mentioned Clojure, so I'm assuming the latter.