What Go Might Be Like With Generics | Hacker News Reader

What Go Might Be Like With Generics

play.golang.org

39 pointssentiental48 comments

Is the only argument that Go users can come up with against generics is that they don't like the syntax? The pretentious nature of the Go community really puts me off from the language, especially when combined with some of the pretentious designs of Go itself.

Is the only argument that Go users can come up with against generics is that they don't like the syntax?

Surely that's the best argument?

> Surely that's the best argument?

As pathetic as it is, "syntax bad" is probably the best argument.

No, the argument is that it's unclear how to fit it into the language.

Typically, generics are implemented using either code generation (causing code bloat) or type erasure (which requires boxing the type). They're not satisfied with either.

A more accurate version of my comment would refer to "Go users" commenting in this thread.

Doesn't Go already do runtime code generation to implement closures?

Go does not generate code at runtime.

They changed how closures are implemented in Go 1.1

There is a comprehensive doc by Russ Cox that explains in detail: https://docs.google.com/document/d/1bMwCey-gmqZVTpRax-ESeVuZ...

They probably wouldn't be happy with any impact on compile times either.

The "code generation = code bloat" argument really fails when you consider that the code generated for a generic function is code that would be written by hand in the absence of generics.

Compare:

    map f [1, 2, 3]
    map g [1.0, 2.0, 3.0]

Versus:

    integer_map f [1, 2, 3]
    double_map  g [1.0, 2.0, 3.0]

In both cases, you wind up with specialized versions of map (one for Integers and one for Doubles). The benefit of the generic version is that the programmer must only implement map once, and the compiler handles specializing it for various types. Without generics, the programmer has to write the specialized version for every type he needs the function for. This creates more tedium for the programmer, and does not reduce bloat in any way.

Caveat lector: Though my examples above are written in Haskell, I don't have enough knowledge of GHC internals to know whether it performs specialization this way. Nonetheless, it could be a reasonable approach for Go.

It seems like you disagree with Russ Cox.[1] Unfortunately, I'm not familiar enough with compilers to reconcile the disagreement. Any thoughts?

[1] - http://research.swtch.com/generic

In this regard, C++ templates suffer from two problems. First, C++ templates are far more general than just generic types (in fact, they're Turing complete). Second, and the cause of lots of redundancy, is that C++ has no module system. C++ has no module system, and instead relies on the linker to provide functionality that could reasonably be provided at compile time given a sufficient module system. I'd say that generics in Go could avoid both of these problems: first by being just generics, and second by leveraging the module system.

Yes, generics will increase compile times. I seriously doubt it will increase compile times by an integer multiple, and most people probably won't even notice.

I'm not entirely sure what's going on that is causing the instruction cache to be underutilized, but it seems to me that the only way to avoid it is to also avoid abstraction in general. As usual, there's a tradeoff between performance and maintainability -- that's nothing new. Pick the appropriate abstractions for your use case.

Russ Cox is wrong in this case because his sample consists of one language: C++. Go is not C++, so it's a mistake to assume it will suffer from the same problems.

To get an idea of how generics could be reasonably implemented, take the Clay programming language as an example: http://claylabs.com/clay/

You're assuming Go programmers will just write out the duplicate code rather than exploring alternatives. This doesn't seem to be what actually happens. Code written in Go isn't as concise as some languages, but it seems to have more to do with error-checking. I suspect we aren't seeing it because built-in types like slices and maps are already generic and people tend not to use fancier collections unless they're really needed.

Interesting word to apply to anything related to golang. Seems more accurate to suggest that golang (and interest) is an alternative to pretentiousness.

The pretentious nature of the Go community really puts me off from the language

I have had the exact opposite experience with the Go community. In particular, I've found community hubs like #go-nuts and the mailing list to be professional at worst and friendly at best, and always helpful.

some of the pretentious designs of Go itself.

How can a design be pretentious? Either you favor the design or you don't, but calling it pretentious is simply projecting your own emotions onto the language.

They may not appear that way if you mesh well with the core ideas of Go. I once mentioned that Go does not fit into my usual project setup - I keep git repos in ~/sources. Go requires me to instead dedicate an entire directory structure to my entire Go workspace, which I have to keep seperate from the other sources. This could easily be avoided by letting me set enviornment variables that would relocate some of these folders (especially bin and pkg) to different places.

This is an example of how Go as a language is pretentious. It's way is the best way, even when no one else does it that way. The community becomes pretentious whenever you draw criticism against these core choices (note this mostly comes from #go-nuts, I haven't spent a lot of time on the mailing list). I like to believe that I can engage in well-reasoned discourse about these things, and I don't think I have seen the same degree of defensiveness and close-mindedness you might see from most other communities.

It is opinionated (a more useful word than pretentious), and it is this way across many things. From style to directory structure to versioning of dependencies to generics. If you actually read the reasoning behind them, I think they are rather well defended by very smart people, but to each their own.

If you really have an issue with some of the very opinionated ideas that come to a large degree bundled with Go, that is fair. That is great even! It probably isn't a good fit for you. Which is fine, there are hundreds of other programming languages that work for you, most are the wild west.

For certain people (like myself) the sanity of Go is striking -- each decision is made for unremarkable and straightforward defensible reasons... a lot of them are community driven over personal preference... it is better for the herd (think: herd immunity) if everyone uses one style and everyone uses one layout... etc. It isn't about being "right" or "needed" by every person, it is about being consistent so you can move from project to project and focus on learning the code, not layout or style, just what the code does.

Go was designed from inside Google, with large teams in mind with many projects.

You make some good points, and I agree with most of them. The thing that troubles me is that Go seems like an exellent language for the most part. I really like it. That being said, it's unfortunate that in order to use it, I feel like some basic choices that I've come to expect as a programmer are taken from me.

Lots of things that are good for communities are restricting for individuals. Even more interesting, some of them lose significant value when anything less than a super-majority fall in line with them (This for example is why I think the Go community sometimes is very "passionate" about getting people on the right path, they are threatening the herd immunity of sane code and layout... one person goes off, others see their example and copy it... chaos!). I think the Go team was wise enough to see that the value of having sane baked in standards from day one FAR outweighed the complaints they knew would follow.

I think many people put too little value on communal norms, they have substantial value and are worth the adaption time. When in Windows C++ -- follow the conventions, when in Linux C -- again, follow the conventions -- and when in Go -- do that same. Fighting the dominant style for established platforms and languages is a mostly pointless, exhausting and sometimes debilitating task generally only done by those too inexperienced to realize how ridiculous it is. Team leads more experienced tend to just choose whatever is the dominate style / layout (preferably per-written up) for that platform/language realizing the benefits for getting ease of reading, consistency, hiring, firing, flexible labor (consultants) and most importantly not having absolutely worthless debates about style and layout.

>It is opinionated (a more useful word than pretentious), and it is this way across many things.

Well, opinionated doesn't mean much quality wise. Either you have the right opinions or the wrong ones. If you have the wrong opinions on something AND are opinionated about it, then you're stupid.

For what its worth, go the language doesn't force that structure. Go the tool does most of that. Most languages (in their pubescent state) don't have self-referential build tools, and so tools get added by third parties (make, scons, etc).

This is not a bad thing -- but it does mean that when a language chooses to ship "opinionated" tools as the default supporting toolset, users gain from the 'convention over code' as rails would call it - you run go build and the tool does the math -- but accomplishing source-tree validation across arbitrary maintainers trees is less trivial than "package-path == path" -- so if you name your code "com.foo.baz.bar", you'll be hurt by its opinions.

That said - if you want to learn the toolchain, 6c/6g/6l (and its 5/8 counterparts) will act like the simplest gcc tools - so long as the benefit you gain from manual definition outweighs the cost, you still win without "go build".

I like the idea of writing Go independently from the Go tool. Could you offer some brief insight into how dependency resolution might work, and link to some projects that break the mold?

Dependency resolution is done by the `go` tool automatically. If your project isn't compatible with the conventions established by the `go` tool, then it cannot infer your project's dependencies automatically.

I'm not aware of any projects that break the mold. Almost everyone that writes Go perceives the benefits of the `go` tool to be greater than the cons.

In another comment, I suggested using symlinks. I do it. Is there a reason why that doesn't work for you?

it's been a while, but something approximating:

-- HN has eaten my asterisks, sed {asterisk} appropriately.

(locate your {5,6,8}{c,l,g} per your go install, or use 'go tool' if you want to go half-way in, I'll use go tool '6' (amd64) for reference).

go tool 6g {asterisk}.go

if you're linking to a final binary:

go tool 6l -o outname {asterisk}.6

Then run ./outname

I'm eliding over linking and includes, but if you run 'go tool 6l -help', you'll find all your expected 'include' and 'link' directory type parameters.

...

All of that aside, I've found it rare that I actively link go code to languages outside of C, and even then, only rarely do I need to share the C subset outside of the 'go' repo. So I'd step back for a second before you go down this road and ask _why_ it must conform. I assume you have a reason -- and if you have a reason and want go as well, exploring the nitty-gritty of 'go tool' is going to be a must. I found it easier to conform with go in a different repository - that may not be an option for you.

One of the biggest "why" answers is software distribution. I distribute my code in source form and users expect to ./configure && make && make install. I feel like there's far too much manual intervention in "the Go way" that I'd be asking my non-Go-savvy users to embark upon.

> Go requires me to instead dedicate an entire directory structure to my entire Go workspace, which I have to keep seperate from the other sources.

Symlinks solves this for me.

> This could easily be avoided by letting me set enviornment variables that would relocate some of these folders (especially bin and pkg) to different places.

AFAIK, `GOBIN` will allow you to relocate `bin`. I'm not aware of any such env var for `pkg`.

> This is an example of how Go as a language is pretentious.

It's not pretension. It's following a philosophy that prefers convention over configuration.[1]

[1] - http://golang.org/doc/articles/go_command.html#tmp_1

>I have had the exact opposite experience with the Go community. In particular, I've found community hubs like #go-nuts and the mailing list to be professional at worst and friendly at best, and always helpful.

That has not been my experience reading go-nuts. Almost any language improvement idea, however valid, is met with snark and you-re-doing-it-wrong answers. And there have been many, and from quite serious developers over the years.

is this trying to solve a particular problem or just pandering to the "... but generics!" crowd of trolls?

because it doesn't look like it's solving anything, it feels positively ugly, and there's no way we'll every shut those people up no matter how hard we try. there's no generics solution that will do that.

thankfully go's authors don't usually favour the internet's opinion on these matters, or we'd be dealing with something even uglier now.

People who want generics, to solve real problems, in Go are trolls?

Gosh that word has lost all meaning at this point.

<T>. they know who they are.

Eventually those who need static typing and parametric polymorphism will switch to Haskell anyway, where both are done in a much better way, both syntactically and implementation wise.

It is undeniable that generics are a quite demanded feature for golang.

We'll see how the language evolves, but I can't see them coming for a "long" time.

I fully support language specialization -- that is kinda the point, it all ends up bits in the end. Rust is a completely different animal than Go yet I think both are awesome!

The idea that all languages have to cater to all people is silly. Generics are ALWAYS a trade-off. None is hard for developers, C++ style is terrible for compile (tons of code-gen, macro crap, duplication, de-duplication stages), and Java style (box-box-box-box) is slow at runtime.

The misunderstanding that generics are free and there lack of inclusion was an oversight rather than a choice is misguided. The Go team aren't fresh faced neophytes, they move with purpose.

Additionally -- if you want lots of features, there are LOTS of ways great languages for you! Leave the small, crazy cadre of people who don't mind C, think Lua is awesome and think Go is great to their (own) devices, we will be OK.

you're awesome! you totally get the idea, people if the language does not fit your needs move on!!!! I mean seriously making all the fuss about generics even though that Go is being used in major projects (Cloudflare, UK.gov) yet we see more people arguing that is not right.

I'm glad Rob Pike and Co. don't give a rats a about such opinions.

I have been writing Go daily at work for about a year and a half. It is now my primary language, and my default choice for any new projects, the way Python used to be. Before that, I come from a background in functional programming (and still find functional programming to be my favorite paradigm).

It seems to me that there are two disjoint sets of people: those who write Go regularly, and those who complain about generics in Go.

Of course, you can interpret this either way you wish!

1) Perhaps those latter people would like Go despite its lack of generics if they only bothered to get familiar with idiomatic Go.

2) Perhaps the lack of generics is precisely what prevents them from writing Go on a daily basis.

But as someone who actually does write Go on a daily basis, and has for a year and a half, I can honestly say that I've only ever missed them a handful of times. And I say this as a functional programmer who is used to being able to call "map" everywhere.

In fact, if I had to prioritize the things that I wish I could change about Go, generics would not be in the top three - not even in the top five[0]. They're just really something that I don't miss anymore.

[0] I could tell you what they are, but that'd be making it too easy - give Go a shot, long enough to realize you really don't need generics as much as you think you do, and then you'll probably have a good idea of the good, bad, and ugly when it comes to Go.

Just wanted to chime in and affirm your experience. I also love functional programming and have used Haskell for several projects (and will continue to do so). But I also use and love Go.

Like you, I've bumped up against areas where some form of generics beyond structural subtyping would have helped me solve a problem more elegantly. But it's never been a huge issue.

I think the primary reason why I'm drawn to Go is that I perceive it to be incredibly simple (like, Lua simple). Not just the language design, but the entire ecosystem---from idioms to tooling.

I've written several non-trivial Go programs, the most recent of which was a server that solved substitution ciphers (for use in subtitle OCR).

I tried to write nice idiomatic Go code. And I'm usually pretty good at adapting my brain to strange languages—I've positively enjoyed Haskell, constraint programming in Mozart, distributed functional programming in Elixir, and quite a few other strange things. (To be fair, I never did get comfortable in Prolog.)

And try as I might, every time I write a couple thousand lines of Go, I walk away in frustration. I love so much about the language, but my actual code keeps disappearing under the weight of error handlers, and stupid little iteration/transformation functions that I have to write over and over again thanks to the lack of generics. (Sometimes I get lucky, and an interface fits well.)

This means that every time I wander down a wrong path (and it's possible to wander down quite a few when messing with OCR algorithms), I end up having to tear up more code than I'd like. It's not fun.

Every time I say this, Go programmers say something like, give Go a shot, long enough to realize you really don't need generics as much as you think you do. But after three serious attempts, it's clear that the programs in my head were never meant to be implemented in Go. Which is too bad: It's a nice language in so many ways.

I have OCR in production live written in pure Go. It does OCR on small specific portions of images to get keywords out to be put into a DB (1B+ page scans). We use tesseract for full page scans (when needed, when our OCR fails). But Go was so easy to write, and so fast to get live for small page partials that we wrote it in a few weeks (idea to live, just implementing well known algorithms) to avoid having to deal with tesseract overhead in the average case.

I am curious about specifically where you got bound up -- and how we managed to via ignorance or blind luck avoid these rough patches. Additionally, I am not 100% sure I understand why you refactor cycle is so brutal. That generally is one of the things I enjoy about Go, lightspeed refactor / dev / test cycles.

Good thing no one is asking you to use Go, Haskell is always around (and Elixir, I guess... I am too used to Erlang syntax, Elixir feels like an ill fitting glove) and we need lots of great languages -- and they SHOULD feel different and some shouldn't be a great fit for you.

^ This is the right way to critique a language: here’s my experience, here’s what frustrated me, and most importantly, the humility to say that the problem comes down to a mismatch between mental model and implementation tool. More like this please.

Agreed (Gopher 1+ years)! My heart still leans towards Erlang, but Go is my current daily driver. The vicious pragmatism at every turn is whats keeps me (and the team) loving it.

It isn't the most elegant, not even close. It isn't the most succinct, not even in the running. It isn't the most flexible -- people would mock you for claiming it is. It isn't interesting in the least, remarkably unremarkable as they say.

But when it comes to just simply getting shit done, and quickly understanding and being able to work in other peoples code, it is second to none. It just doesn't get in your way, and out of the box it gives you simple syntax, great tools and easy deploys.

How would you recommend becoming familiar with idiomatic Go?

I've read various articles including (but not limited to) tutorials, made a point of exploring a few open source projects and I've written a few thousand lines of Go. I enjoy writing Go, but I have a hard time so far figuring out if what I write is idiomatic.

Effective Go: http://golang.org/doc/effective_go.html

Short of that, read the source of some standard library packages. They are quite approachable.

> How would you recommend becoming familiar with idiomatic Go?

By reading the source code of the standard library. It's directly linked from the API documentation.

<T>errible to my eyes.

tl;dr: <T>

How about this instead? http://play.golang.org/p/hED7faR0q_

I use generics every day in typescript. I'm waiting to use go until it has them.

I'm more interested in what Go might be like without whiners.

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