Comment by dizzystar | Hacker News Reader

Comment by dizzystar | Hacker News Reader

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>> * I actually don't think immutability is as key to concurrency as it gets hyped to be. Clojure which I've used and enjoyed does tend to get in your way with the immutability by default.*

I don't want to join into a language war, but I wanted to point out two things with this statement:

1- I can show you video lectures from 1985 that discuss mutability -vs- immutability in concurrent systems. Immutability won this war, at least in the research realm, 30 years ago.

2- Rich Hickey worked on massive telephone systems and created Clojure, at least in (large) part, out of frustration of dealing with mutation.

So there's a long line of research backed by "real world" experience showing mutation not holding up well for concurrency. Erlang is another example.

Regardless, I do agree that immutability may not be what it is hyped up to be, especially if you are looking for the mythical silver bullet, but it most certainly isn't over-hyped if you compare it to mutation, and the ideas are still quite young and being tested. Give it 20 years and I suspect there will be another paradigm shift at some point.

My point is that Go gives you the option of immutability. Not immutability or something in between. I frequently send messages using non reference types which incurs a copy but means that I don't have to worry about who owns this code. It's easy since Go has pointer and non pointer types. Java has reference types and you have to design the object to be immutable by hiding fields behind methods and using annotations. Clojure goes to the other extreme. Go sits in the middle. Which is relaxing.

Go can't do immutable updates efficiently (yet) because it doesn't have a persistent data structure implementation for vectors, maps, sets, etc.

Java has a keyword 'final' for immutable objects.

> 1- I can show you video lectures from 1985 that discuss mutability -vs- immutability in concurrent systems. Immutability won this war, at least in the research realm, 30 years ago.

Maybe, but concurrency based on mutability seems to have won this war in the real world these past thirty years.

Immutable systems might be easier to design in theory but we haven't seen this proven in the battle field yet, and the fact that most of the concurrent code today runs on mutable structures shows that it can be done.

Immutability has worked out really well for a lot of real-world systems built with Erlang.

The main (and close to only) user of Erlang was Ericsson, and here is what the Wikipedia has to say about it [1]:

"Shortly thereafter, Erlang was banned within Ericsson Radio Systems for new products, citing a preference for non-proprietary languages. The ban caused Armstrong and others to leave Ericsson"

Not exactly a strong endorsement for Erlang.

[1] http://en.wikipedia.org/wiki/Erlang_(programming_language)

"The ban caused Armstrong and others to leave Ericsson.[6] The implementation was open sourced at the end of the year (1998).[3] The ban at Ericsson was eventually lifted, and Armstrong was re-hired by Ericsson in 2004.[6]"

It is really hard to imagine that you made that excerpt in good faith. Read the very next sentence in the article.

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