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Erlang's error checking model is a great deal more like Go's than he thinks. Erlang is in the "exceptions are exceptional" camp too, and idiomatic code should not be throwing exceptions around willy-nilly.

Go is noticably more fragile with errors. Unhandled exceptions (which are just a fact of life unless you're a perfect programmer) will result in the entire program terminating if you don't have something that handles it. This behavior is forced on it precisely because of the shared memory model (one of the actual big differences); if one goroutine has f'ed up, you simply don't know what the state of your program is anymore. (Theoretically you could do better than that, but not simply.) Since Erlang memory is isolated, it can kill just that one process, and the other processes can pick up the pieces. (Not necessarily perfectly or without loss, but in practice, really quite well.) Consequently, for any serious Go program, you're still going to have to choose an exception handling policy, it's not as if it has gotten away from exceptions. Failures are a fact of life... for all you know, memory was corrupted. Again, the difference here is not "error handling policy" but the longer term consequences of shared vs. isolated memory spaces. If you just type up idiomatic Erlang OTP code, you have to go out of your way to not have a bulletproof server; if you just type up idiomatic Go code it's on you to make sure you're not excessively sharing state and that you aren't going to see your entire server doing tens of thousands of things come down due to one unhandled exception. Go programmers need to be more worried about error handling in practice than Erlang programmers, since Erlang programmers aren't facing the termination of the entire world if they screw up one thing.

There's also a recurring pattern in newer language advocates in which they will in one year claim it's a good thing that they don't have X, and next year tout to the high heavens how wonderful it is that they just implemented X. I went around with the Haskell world on a couple of those issues ("no, strings are not linked lists of numbers", "yes they are you're just not thinking functionally and inductively dude, and by the way, six months later, check out this totally radical ByteString library, and when that still turns out not to be stringy enough hey, check out Data.Text six months later..."). Thinking you can get away without OTP is likely to be one of those for Go. No. You need it, though I have questions about whether it can even be built in Go, because one of the other actual differences between the languages...

... which is Channels vs. Processes. Go has channels, but you can't tell who or what has them, and there's no such thing as a "goroutine reference". By contrast, Erlang has processes, but no way to tell what messages they may send or receive, and there's no such thing as a "channel". Again, this has major impacts on how the system is structured, in particular because it is meaningful to talk about how to restart a "process" in a way that it is not meaningful to talk about how to restart a "channel".

Go advocates desperately, desperately need to avoid the temptation to explain to themselves why Erlang isn't as good, because then they'll fail to learn the lessons that Erlang learned the easy way. There's a lot of ways to improve on Erlang, but let me tell you that despite those opportunities, Erlang as a language is one of the wisest languages around, you do not want to try to exceed it by starting from scratch. Learn from it, please, I want a better Erlang than Erlang, but talking yourself into how Go is already better than Erlang isn't going to get you there.




> Learn from it, please, I want a better Erlang than Erlang, but talking yourself into how Go is already better than Erlang isn't going to get you there.

That's fantastic advice for language advocates everywhere:

Rather than pissing on other languages, learn from them, understand what good there is in them, and figure out how to build on that.

Sometimes that's difficult: if you're forced to work 10 hours a day with shitty PHP code... you lack perspective, but even that language has some pretty good things, although (IMO) they mostly revolve around the runtime/environment and how easy it makes it to get something up and running.

For a long time, I was really into Tcl, and still think it's a cool language in many ways, but some of the people that were really into advocacy seemed to get into this mentality where there were no blemishes, only features. That kind of thinking makes you blind to what really does need fixing, and makes it difficult to evaluate things objectively.


the PHP devs I know really seem to embody a culture obsessed with 'shipping' that I'm not sure can be matched, and I'm really a big fan of it for that, in spite of PHP's huge wackyness.


true. Problem with PHP is that you cant really write backends with it ( I mean stuffs not related to the http interface ) ,like one could do with ruby , python .net or go. That's fine because native solutions exist. But the lack of general purpose of PHP is its greatest weakness.


What's with the "dude" and "totally radical"?

The problem with [Char] for bulk text IO was well acknowledged when I wrote bytestring. To quote:

"The Haskell String type is notoriously inefficient. We introduce a new data type, ByteString, based on lazy lists of byte arrays, combining the speed benefits of strict arrays with lazy evaluation. Equational transformations based on term rewriting are used to deforest intermediate ByteStrings automatically. We describe novel fusion combinators with improved expressivity and performance over previous functional array fusion strategies. A library for ByteStrings is implemented, providing a purely functional interface, and approaches the speed of low-level mutable arrays in C."


That sounds cool, and a lot like Erlang's iolists, right? The idea being that lists of byte arrays lets you do IO without all the memcpy that might otherwise be required?


I'm in the same situation as this author. I've used Go a fair bit (and will continue to do so), but have recently been reading "Learn You Some Erlang". So far, I have to say: when it comes to concurrency, hands down, Erlang is better. I don't think many people from the Go side are claiming that Go is better. In fact, I'm pretty sure most just want something similar to Erlang available in a familiar, imperative language. I really hope something similar to OTP emerges for Go; its interface functionality would be useful for that. Process linking and monitoring are absolutely awesome and could only be sloppily hacked into a Go program. However, Go does have some good things: familiarity (syntactically and a lack of surprises), the ability to do some number crunching (something Erlang cannot do), and "structs" that aren't hacked tuples (records).

Honestly, if the author is treading on 'errors vs exceptions', I don't think he has grasped the big picture yet. I'm not even finished with the book and I can tell you that. In fact, I usually hate exceptions, but with how monitoring works, I've found it quite elegant.

One other super important thing to note is that Go's channels don't work over a network. There was an effort to create a "netchan" package to do just this, but so far no one has implemented it cleanly enough to be satisfied.


> Erlang as a language is one of the wisest languages around

It is a truly one of the few industrial, battle hardened functional and concurrent languages. I think languages that came after it and claim to have those features should at least somehow justify how they have improved on what's there.

Now ok, there is a balance. Someone spent time, and effort. Wrote a new language and open sourced it. Should we criticize them? They are giving it away and here we are telling them their work has some big warts and someone already built something similar. Yeah, it is an interesting question, and how heavy the criticism should be....


>Haskell world on a couple of those issues ... I want a better Erlang than Erlang

What is your opinion of Cloud Haskell? It is a library which attempts to do exactly that.


> I want a better Erlang than Erlang, but talking yourself into how Go is already better than Erlang isn't going to get you there.

I don't mean to go against this point--it's very true, and I think it's important--but I think this conversation (and most comparisons of Go with Erlang) miss something: Erlang is a platform (it has its own VM, and basically its own OS, just relying on the outer OS as a hypervisor.) Meanwhile, Go isn't a platform, nor is it trying to be. Its designers (Rob Pike and Ken Thompson) already made the platform, first, a long time ago. It was called Unix.

These folks are serious about Unix--they want you to use it. They aren't going to reimplement Unix on top of Unix if they can help it. Unix is already the native set of abstractions they think in terms of[1]. An Erlang "release" (VM + source) should be compared to an entire Unix VM with a disk containing some Go binaries; not just a blob of Go source on its own.

Which is to say, the equivalent of the OTP exists for Go, but it isn't in Go--it's in Unix. OTP services are fundamentally "platform-level" things, and Unix provides them. Where are supervision trees? They're in upstart(8). Where is logging? rsyslog(8) will do it. And so forth.

There's nothing wrong with treating an individual Go process as equivalent to an Erlang process (other than overhead, but that's a problem with your Unix implementation, not with Unix as a platform). Make each Go process (that is, Go binary) have a single responsibility, so it can crash on its own. Then, give it a supervisor who can restart it with the right state. Some processes will still need to be larger, of course--goroutines still serve a purpose--but when the process crashes, you'll lose all of that, so don't put everything in there.

Since you now have multiple Go processes running, you'll need to do IPC. It's Unix: do it with sockets. What do you send on them? You can import a raw struct-specifier header file (or a whole client stub library, like in Erlang) from the include/ directory of each other process that specifies types it will understand, and then speak that "protocol" to it. Or you can use a ProtoBuf spec, to make your process more friendly for third-party use. Or, you can use plain text, like most Unix processes.

A single goroutine in each Go process should manage reads from this socket, deserialize the messages coming from it, and stuff them on channels relevant to their meaning. Then, the other parts of your process that care about external messages can receive on those channels when they wake up. Sounds a lot like an Erlang process inbox, doesn't it?

And so forth.

I think a lot of people are used to languages that provide their own insular inner-platform (Ruby, Python, Erlang, C#, Java, etc.) with its own implementation of everything from process scheduling to message passing to bytecode format to exception-handling, and think that Go is another one of these. Go is not this. Go is, despite all its modern trappings, "better C", and like C, it is heavily bound to Unix for most of the operations stuff that is important to high-availability et al.

Try Go with Unix--it might change your opinion on how many decades of hard-won experience Go is leaning on :)

---

[1] Well, okay, their abstraction-set probably hews closer to Plan 9 these days; Go even uses the term "runes" to refer to Unicode code-points and so forth. Still, all the ideas are backportable without too much of a fight.


> Meanwhile, Go isn't a platform, nor is it trying to be. Its designers (Rob Pike and Ken Thompson) already made the platform, first, a long time ago. It was called Unix.

This is great, and I think many of Go's advocates - including devs at Google - underplay it. I don't understand why, particularly given the pedigree of Pike and Thompson.

My approach to building large systems in Go is based around processing pipelines, and tries to be as UNIX-y as possible. The interface types in the io package particularly fit the everything-is-a-file model, where processes can do one thing well while having their inputs and outputs connected to pipes, files, sockets, named sockets, devices, etc.

In short, building complex systems with Go components has made me a better UNIX programmer, a level that I could never quite reach in C due to all the distractions of memory management and unsafety.


I have been playing around with Go on Windows- I really like it (especially the built-in concurrency types) but after reading these comments I feel like I would be better off trying it on UNIX (my mac will do). It probably does not help I am still somewhat lost on UNIX, either, but could you give an example of what a 'processing pipeline' approach would look like? That sounds very much like functional programming to me is that correct? Any advice on tackling UNIX and Go at the same time would be much appreciated!


A well-engineered UNIX-y "pipeline" is not unlike an impure functional program, yes. Well-behaved processes share no state (i.e. they don't contend over the same files), and messages and data passed over UNIX pipes are immutable, much like data in a functional program.

For example: one system I implemented needs to take a few hundred very large CSV files every day, aggregate and sort them, perform some complex processing on them, and output a result in a very different format to many different output files. It's an extremely complex system, and each component is in Go, performing a specific task, e.g.:

* combining the many source files * cleaning the source files * performing some aggregation on the stream * splitting the stream into many parts that other components can read from in parallel ('named pipes' in unix make this very nice) * splitting the stream into many output files

etc. Every component is dumb and does one thing, but a single controlling program is responsible for handling command line arguments that describe the overall outcome and setting up the stdin and stdout stream of all of the components to create the final result.

There's a beautiful simplicity to systems implemented like this, and it means you can take advantage of existing tools like grep, awk, sed, sort, cut, etc. to do a lot of the heavy lifting more reliably and quickly than you could probably implement yourself, while still coding the overall system at a reasonably high level of abstraction. Go doesn't lead to this approach directly, but it's very pleasant working with it as a citizen of this wider environment.


A very good (free) book for getting started, IMO: http://www.catb.org/esr/writings/taoup/html/


Fine. Then the UNIX platform is a great deal weaker than the Erlang platform on the supervision tree front, and if you'd like to fix it there, fine, but it's still not comparable as of this moment. Killing a Go OS process is not even remotely similar to killing an Erlang process, and restarting a Go OS process is not even remotely similar to restarting an Erlang process.

In fact, let me underline that... the UNIX platform is a GREAT deal weaker than the Erlang platform on this front. It has faint shadows of what Erlang supports, which are incredibly heavyweight, far less reliable, FAR less granular, and effectively can not be used the way Erlang's can be. It's an answer, sure, but it's not even in the same league in this particular way, so don't fool yourself otherwise.

Of course UNIX has other advantages, but, well, that's why I run Erlang on UNIX, so....


>Unhandled exceptions (which are just a fact of life unless you're a perfect programmer) will result in the entire program terminating if you don't have something that handles it

I am in danger of being downvoted here as I am a bit out of my depth but after reading the go language documentation it seemed to me that go standard libraries are designed to throw exceptions internally but recover gracefully and return an error type to the caller- thus avoiding program termination- I thought that was quite a nice idiom. 'Imperfect' programmers would have to explicitly call panic without recover to cause termination?




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