Why did you decide “against” using Erlang?

Question

Have you actually "tried" (means programmed in, not just read an article on it) Erlang and decided against it for a project? If so, why? Also, if you have opted to go back to your old language, or to use another functional language like F#, Haskell, Clojure, Scala, or something else then this counts too, and state why.

Answer 1

I love Erlang from the concurrency standpoint. Erlang really did concurrency right. I didn't end up using erlang primarily because of syntax.

I'm not a functional programmer by trade. I generally use C++, so I'm covet my ability to switch between styles (OOP, imperative, meta, etc). It felt like Erlang was forcing me to worship the sacred cow of immutable-data.

I love it's approach to concurrency, simple, beautiful, scalable, powerful. But the whole time I was programming in Erlang I kept thinking, man I'd much prefer a subset of Java that disallowed data sharing between thread and used Erlangs concurrency model. I though Java would have the best bet of restricting the language the feature set compatible with Erlang's processes and channels.

Just recently I found that the D Programing language offers Erlang style concurrency with familiar c style syntax and multi-paradigm language. I haven't tried anything massively concurrent with D yet, so I can't say if it's a perfect translation.

So professionally I use C++ but do my best to model massively concurrent applications as I would in Erlang. At some point I'd like to give D's concurrency tools a real test drive.

Answer 2

I returned to Haskell for my personal projects from Erlang for the simple virtue of Haskell's amazing type system. Erlang gives you a ton of tools to handle when things go wrong. Haskell gives you tools to keep you from going wrong in the first place.

When working in a language with a strong type system you are effectively proving free theorems about your code every time you compile.

You also get a bunch of overloading sugar from Haskell's typeclass machinery, but that is largely secondary to me -- even if it does allow me to express a number of abstractions that would be terribly verbose or non-idiomatic and unusable in Erlang (e.g. Haskell's category-extras).

I love Erlang, I love its channels and its effortless scalability. I turn to it when these are the things I need. Haskell isn't a panacea. I give up a better operational understanding of space consumption. I give up the magical one pass garbage collector. I give up OTP patterns and all that effortless scalability.

But its hard for me to give up the security blanket that, as is commonly said, in Haskell, if it typechecks, it is probably correct.

Answer 3

The JVM is not a tool, it is a platform. Although I am all in favour of choosing the best tool for the job the platform is mostly already determined. Unless I am developing something standalone, from scratch and without the desire to reuse any existing code/library (three aspects that are unlikely in isolation already) I may be free to choose the platform.

I do use multiple tools and languages but I mainly targetg the JVM platform. That precludes Erlang for most if not all of my projects, as interesting as some of it concepts are.

Silvio

Answer 4

I have used Erlang in a few project already. I often use it for restful services. Where I don't use it however is for complex front end web applications where tools like Ruby on Rails are far better. But for the powerbroker behind the scenes I know of no better tool than Erlang.

I also use a few applications written in Erlang. I use CouchDB and RabbitMQ a bit and I have set up a few EJabberd servers. These applications are the most powerful, easiest and flexible tools in their field.

Not wanting to use Erlang because it does not use JVM is in my mind pretty silly. JVM is not some magical tool that is the best in doing everything in the world. In my mind the ability to choose from an arsenal of different tools and not being stuck in a single language or framework is what separates experts from code monkeys.

PS: After reading my comment back in context I noticed it looked like I was calling oxbow_lakes a code monkey. I really wasn't and apologize if he took it like that. I was generalizing about types of programmers and I would never call an individual such a negative name based on one comment by him. He is probably a good programmer even though I encourage him to not make the JVM some sort of a deal breaker.

Answer 5

Used it for a message gateway for a proprietary, multi-layered, binary protocol. OTP patterns for servers and relationships between services as well as binary pattern matching made the development process very easy. For such a use case I'd probably favor Erlang over other languages again.

Answer 6

I am not going to even look at Erlang.

Two blog posts nailed it for me:

1. Erlang machinery walks the whole list to figure out whether they have a message to process, and the only way to get message means walking the whole list (I suspect that filtering messages by pid also involves walking the whole message list)

   http://www.lshift.net/blog/2010/02/28/memory-matters-even-in-erlang

2. There are no miracles, indeed, Erlang does not provide too many services to deal with unavoidable overloads - e.g. it is still left to the application programmer to deal checking for available space in the message queue (supposedly by walking the queue to figure out the current length and I suppose there are no built-in mechanisms to ensure some fairness between senders).

   erlang - how to limit message queue or emulate it?

Both (1) and (2) are way below naive on my book, and I am sure there are more software "gems" of similar nature sitting inside Erlang machinery.

So, no Erlang for me.

It seems that once you have to deal with a large system that requires high performance under overload C++ + Boost is still the only game in town.

I am going to look at D next.