Golang: How to Update APIs for Generics

https://github.com/golang/go/discussions/48287

by 0xedb • 5 years ago

126 63 5 years ago

github.com

37ef_ced3• 5 years ago

This is the way:

Use new major versions for stdlib packages, e.g., sort/v2

xyzzy_plugh• 5 years ago

Certainly this is true, but I wouldn't put it past rsc & co to find some magical incantation that provides full backwards compatibility. In particular the alias keyword was quite succinct and not abused much.

tikkabhuna• 5 years ago

Sounds like a nightmare for newbies getting started. If this is the way forward, and I agree its the most Go-like, I would like to see good support for warning users to use v2 and why they need to.

YesThatTom2• 5 years ago

Quite the opposite. Naive users will not be affected. They’ll just use generics and not realize that for certain types the code generated is more specific.

Or are you assuming newbies read the standard library source?

blondin• 5 years ago

just an aside but that github discussions feature looks amazing -- first time i am noticing it. so many "issues" are really just discussions. kudos to the github team.

lerax• 5 years ago

I agree, that is a great feature. Now we can separate what is a true project issue than a broad question/discussion

icy• 5 years ago

It irks me that they have both votes and reactions.

sk0g• 5 years ago

You can have a funny/ insightful comment that doesn't add to the discussion, so it makes sense to me at least. It's like Facebook + Reddit/ HN voting systems at once.

qaq2• 5 years ago

Can't wait for the thing to land. My only remaining wish is sum types

rawoke0836002• 5 years ago

THIS ! and "pattern-matching" :)

a-saleh• 5 years ago

So, in the end all of languages move closer to StandardML :D Like even python has sum-types and pattern matching now!

xmorse• 5 years ago

That would be awesome!

tonyedgecombe• 5 years ago

And exceptions :)

k_bx• 5 years ago

Were there discussions? What is the general impression, is there hope?

yutijke• 5 years ago

I have never used golang but from my reading of the type parameters proposal, it also includes an approximation of "Sum types".

You can define an interface with a closed set of types

type Number interface { float64, int64, ... }

Now, the value will be boxed, so you will not have no-allocation sum types but you can approximate boxed sum types with this I think.

cube2222• 5 years ago

Approximating closed sum types is easy already, by creating an interface with a stub private method and implementing it for all variants. Then it's not possible to implement it using a type outside of that package.

The main thing that's lacking is compile time checks whether variant matching is exhaustive.

zerr• 5 years ago

Any updates regarding the if-hell of error handling?

neetle• 5 years ago

"Try another language instead" is always a valid option.

There isn't anything wrong with a language just not jiving with your sensibilities.

mseepgood3• 5 years ago

They spent months consolidating feedback and made two proposals. The community didn't want change. Now they are no longer working on it and are focusing on getting generics out.

_6pvr• 5 years ago

(Not attacking you) Do you write a substantial amount of Go very frequently?

brabel2• 5 years ago

They're still trying to decide basic stuff like how to transition existing APIs to generics!? Wow, that means it will be a long time for generics to land on stable Go.

arghwhat5• 5 years ago

Because it's far from basic stuff when you have to consider stability guarantees.

pjmlp8• 5 years ago

You know how to avoid those problems?

By having them since the begining, it is not as other languages haven't gone through the path of bolting on generics after the fact, as an example for others to learn from.

brabel2• 5 years ago

I mean basic in that it's like the feature can't even be added if you don't solve that.

_ph_2• 5 years ago

No. The generics can be added without this discussion to be resolved. It is about upgrading existing APIs to make full usage of generics. Take math.Min for example. Currently it compares floats. Without changes, it continues to do exactly that. The question now is, how to have a new version math.Min that fully uses generics, without destroying backwards compatibility for existing code. Resolving this most elegantly is desirably, but not a necessity. Especially it can be added a few releases later than the generics themselves.

ddevault2• 5 years ago

This is Go's Python 3 moment. This creates a hard fork of the ecosystem, with a before and after, and all existing Go code is now un-idiomatic and will have to be refactored, rewritten, or replaced.

ngrilly• 5 years ago

Not really. Python 3 introduced breaking changes requiring modification of your code base. That's absolutely not the case here for Go. You can still compile and run your code unchanged. You are also overestimating the magnitude of the number of line of codes impacted by the new style using generics.

ddevault2• 5 years ago

It's not a breaking change, but it is a radical change for what it means for Go programs to be Go programs. All Go programs are now written the "wrong" way. Or, in other words: all present Go programs would not pass a code review if they were introduced following the release of Go 2. This also affects many libraries throughout the ecosystem, increasing the API churn and burden on downstream projects. It will create millions of man-hours of work for Go users.

declnz• 5 years ago

Surely this is more like... when Java 5 introduced Generics, and everything changed a lot (eventually)?

jcelerier• 5 years ago

I'm going to go out on a limb and suggest that we use the Of suffix for generic container types

do people ever learn anything.. conventions don't work, only things checked by the language grammar matter

tazjin• 5 years ago

This is explicitly the language for not learning things we've figured out over the last decades so ... no ;-)

pjmlp8• 5 years ago

Given that some of the language designers had the same approach for safety in C versus the existing alternatives, yep people don't learn much.

SPBS• 5 years ago

Doesn't matter, the standard library simply has to set a consistent example for people to follow. They can choose to ignore it.

Golang: How to Update APIs for Generics

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