[Taek]

Find a different way to solve the problem. I've written close to half a million lines of code in Go and the lack of generics has been a pain point in maybe 1% of that? Usually, if you are thinking about generics you are reaching for abstraction when you don't need to be.

If you really need generic structures you can use the interface type but generally there's a simpler solution that doesn't require generics.

[leshow]

It's not as if it's a niche problem requiring a niche solution though. The problem is "how do I write my own data structures" and to the best of my knowledge Go's answer is: copy-paste everything and edit for each concrete type, use code gen, or pay runtime cost for interfaces. All of those solutions seem more complex than just having a type parameter.

[jshen]

They seem more complex compared to a type parameter when you are only thinking about this narrow situation. However, generics are not limited to this narrow situation and will cause complexity far beyond what you are imagining.

Having said that, I honestly don’t know if generics are a net positive or not. What I can say is that go is one of the few languages where I can jump into an arbitrary go code base and make sense of it relatively easily. Risking that is a scary proposition for me.

[leshow]

I'm well aware when they are useful, I've been using them in languages for the past 10 years. By the same token though, leaving type parameters out of the language has had far reaching implications outside of this "narrow" situation (I'll put forth that implementing a data structure isn't a narrow situation). Error handling and the lack of sum types also seem particularly egregious and are heavily influenced by the lack of generic types.

> Having said that, I honestly don’t know if generics are a net positive or not. What I can say is that go is one of the few languages where I can jump into an arbitrary go code base and make sense of it relatively easily. Risking that is a scary proposition for me.

I don't see how type params would make this harder, I daresay I can think of a lot of instances it's much easier. The caveat is that you simply don't understand them, in which case it's a good thing to learn as many languages do have them.

In any case all these arguments are well trodden so I'm probably wasting my breath re-hashing here.

[jshen]

I’ve been using them for the past 30 years and have come to a different conclusion. You have plenty of languages that do what you want. I hope go doesn’t lose what made it different

[leshow]

Oh sorry, you were saying lack of generics were the reason you could make sense of code easily, implying that if a language has generics you can't make sense of it. That seems juxtaposed to having used them for decades. In any case I can tell you're passionate about this so I think we can just agree to disagree.

That said I don't think there's much "hope", from the looks of things it is coming to Go.

[jshen]

I'm hoping that Go still keeps it's relative simplicity. It's lack of inheritance gives me hope that generics won't be as complicate as it is in other languages.

I understand generics well, I just find code bases that use a lot of abstractions harder to read than Go.

[takeda]

You know? Original Java was a fairly simple language :) Generics were added in 2004 in J2SE 5.0.

[garethrowlands]

Just call it parameterisation, it's less scary then. The unknown is always scary but having the ability to parameterise - including types - is well traveled ground.

[Fire-Dragon-DoL]

This can be said for any programming language and any community: there will always be bad code written by someone.

Generic data structures are provided in many programming languages and there are many people that are very experienced in writing some of these, so being able to reuse, it's precious.

In general the lack of generic price surfaces when you write libraries, not applicative code. But libraries are a big portion of a codebase.

[jshen]

I’ve been coding for decades. I’ve used all the fancy functional languages, written production code at scale with complex type systems, etc. my experience, they don’t add a lot of value compared to the costs. In my old age I’ve grown to prefer go for it’s simplicity. I hope we don’t lose it, and you all have the option of using the myriad languages that already do what you are looking for.

[Fire-Dragon-DoL]

I think you misunderstood my point (maybe): I totally agree with you. I've been coding for many years and coming from Ruby where you can do "the worst stuff you can think off" (really bad stuff: monkey patching, building DSL etc.), I came to Go exactly to get relief from all of that. I don't trust people having their hands on all that power.

Still in my short Go career, I worked on at least 4 libraries, one of those needed generics to gain a huge performance boost, the other worked around the lack of generics, but I still wish it had it (a special kind of logger). In applicative code, the main issue with lacking of generics is the lack of generic slices functions (map/select). Initially I thought it would be fine, but then I wrote a piece of code that was visibly involved in copying data from one slice to another with some changes and that "shadowed" the "central" part of the code behind a bunch of loop codes. In those cases, to improve the ability to easily scan through the code, I wish I had some generic slice function to deal with it. I appreciate doing loops, but sometimes they are verbose enough to hide the interesting part of a piece of code. This is especially visible in applicative code where usually performance is not as important as much as the business logic.

[brundolf]

Go has some "special" built in functions like len() that work across different structures. What if instead of adding generics they added more of those special functions for working with slices as you describe? Would that have solved your problem?

[danellis]

> Usually, if you are thinking about generics you are reaching for abstraction when you don't need to be.

That's pretty laughable considering the language designers included type-parameterized collections in the language. Apparently they recognized the need for them; they just didn't think you were smart enough to make your own. After all, Go was explicitly designed for programmers who are, in the words of its creator, "not capable of understanding a brilliant language".

[VirusNewbie]

Probably a bunch of that code was needless boilerplate you could have gotten away with not writing if you had abstractions such as parametric polymorphism.

[tengbretson]

Maybe you could have gotten that work done with fewer than 500,000 loc if you used a language with a better feature set.

[Taek]

Lines of code is a complete red herring. It takes me less time to read and review 500 lines of Go than it does 100 lines of JavaScript.

Sometimes - especially in other languages - you see a piece of "elegant" code that does something complex in line 3 lines, and you think "hmm, this is a puzzle, and I'm going to be staring at it for 20 minutes before I'm convinced that its 100% correct."

We actively tell our engineers not to be clever. Write boring code that is obviously correct, and don't worry if your boring code is 25 lines when the elegant code is 8. It takes you longer to write the elegant code, and it takes the reviewer longer to read it, and often times (though not always ) it's also more difficult to test.

I love Go because of how boring and consistent and easy to read it is. The language and the task of "programming" melt away and instead you get to focus on solving problems.

[VirusNewbie]

Study after study has shown people fail at repetitive tasks, it is likely you do a much poorer job reviewing that 500 lines of Go code than your javascript.

Using generics isn't 'clever'. It's like saying a loop is clever. It's abstraction, the opposite of clever.

[jshen]

And it would have been far harder to read for those new to the generic code base. Complex abstractions make people feel smart, they rarely make code easier to understand or maintain.

[fiddlerwoaroof]

Optimizing for people that are new to a codebase seems like a mistake to me: onboarding costs are relatively minimal and finite (per developer) whereas maintenance costs have no fixed bound: if generics let you exclude invalid states by design (and they do: this is one of the biggest advantages of parametric polymorphism vs. interfaces), they will be useful for keeping maintenance costs under control.

[Taek]

You definitely want to optimize for people who are new to a codebase. Over enough time, the codebase grows to a point where essentially _everyone_ is new to each area of the code, because nobody has touched that code in 2-3 years and the person who wrote it may not even be with the project anymore.

Even for your own single-person projects - if you get fancy with the code, 6 months later you find it's a lot harder to get back into and mess around with than if you had written the code as though you were presenting it to a beginner.

[erik_seaberg]

Management is responsible for making sure that doesn’t happen, by retaining experts and demanding documentation and investing in ramping up new experts. Making the code bigger because each line does less is not going to save us from nobody understanding prod, and a short learning curve puts a low limit on the value of our staff (who quickly run out of tools and stop improving in clarity and productivity).

[fiddlerwoaroof]

You want patterns that are well-known to the maintainers, but this is different from “optimizing for the new”: consistent idiomatic use of a library like XState or Ramda in a JavaScript project can cause a high onboarding cost (because the new developers don’t know the library well) without any corresponding ongoing cost.

[jshen]

I’m guessing you like Haskell and similar languages, because that’s the natural conclusion to your line of reasoning.

I don’t agree with you, but I could be wrong. There are plenty of languages that are aligned with your point of view. I like go because it was going a different direction, and I hope that doesn’t change. You can use Haskell, scala, typescript, etc to get what you are looking for.

[aptenoforst]

How is a generic data structure a COMPLEX ABSTRACTION?

[theshrike79]

If people would stick to common generic data structures (like a map/list that can handle any datatype), i'd be fine with abstractions.

But some people have a tendency to play code golf with their codebases.

I have, for example, encountered a "generic data structure" that looked like a normal linked list on the surface. BUT, it actually sorted the largest three items in the first 3 cells and the average in the 4th.

That was multiple days of work wasted because someone decided to be cute with their data structures. And that wasn't even the only one of such "generic" monstrosities in the code.

[bmn__]

So blame goes to the hammer instead of the carpenter?

[carnitine]

What does that have to do with generics? Surely they’d have written the same bad code monomorphised?

[h4x0r12345]

Generics (and other abstractions) are not the root cause. Go was a pragmatic defence against mediocre developers. The majority of developers are mediocre by definition, and will abuse _any_ abstractions to create Rube Goldberg contraptions and monstrosities.

[pjmlp]

20 years ago those mediocre programmers were using Visual Basic and Java, so look for the past to see where future goes.

[Fire-Dragon-DoL]

Well there is a valid point of abuse in abstractions. The ruby world is a disaster because of the power provided combined with people reaching out to all sorts of abstractions the entire time for purely experimental reason.

It's true that applicative code shouldn't need generics in probably more than 90% of the times, however the lack of it affects library authors quite heavily

[jshen]

They are complex. I’m guessing you haven’t thought about them much beyond the trivial use cases.

[h4x0r12345]

No, it's relative. For the top 5% - 10% of developers, generics are a useful tool for doing their job efficiently. For the bottom 50% of developers, generics are complex and confusing, and only provides more footguns.

[citrin_ru]

For 0.5%-1% C++ is a powerful tool which allows to quickly (thanks to rich abstractions) to write high-performance code.

For merge mortals it is a tool hard not to misuse full of hidden traps and debugging of code written even by the very best developers (surprise - it has bugs too) is a challenge.

Go just did a step towards C++, even if a tiny one.

[Taek]

And the top 1% of developers know that you are most productive when you stick to the simplest primitives ;)

I jest, but I also don't. All the best developers I know strongly prefer footgun-free libraries and primitives. The advantage is that you don't _need_ to spend brain cycles checking and double checking that it was written correctly, and when you want to make changes you don't need unwind an elaborate abstraction to stretch it further.

In martial arts (I'm a second degree black belt), the third move you learn is the round house kick (turned leg kick - the first two moves are the punch and the straight leg kick). At the olympic level, 70% of all points are scored using a roundhouse kick.

The other funny thing about the roundhouse kick is how much you can learn from watching someone do a single one. You can tell the difference between someone with 2 years of experience and 3 years of experience, and you can _also_ tell the difference between someone with 15 years of experience and 20 years of experience.

The point of this story being that masters are masters not because they can do elaborate techniques, but because their command over the simplest techniques is superlative.

I've found in life that this applies to pretty much everything. Martial arts, programming, painting, cooking, and effectively any task that definitively has some people who are better than others.

[sterlind]

so as an example, I've used priority queues a lot. you need them for Dijkstra.. apparently golang has a heap package which lets you push and pop `interface{}`. sure you can cast, and I guess people have to, but why couldn't Go just call `interface{}` object or any? the awkwardness of the convention suggests an unwillingness to accept failure.

[xh-dude]

Parametric polymorphism is a better fit for container types IMHO. There are some interesting notes here…

In Go prior to generics, interface{} is an escape hatch less frequently needed but not necessarily much safer than void*. Post generics, interface{} is suddenly more useful and will be aliased by ‘any’.

The way the std lib heap works in Go, an implementation doesn’t have to mention interface{}. Using the Go std lib solution is about satisfying a few interfaces, defining some methods for sorting and swapping over the element type. The use of interface{} is internal.

Go’s generics solution is going to have type constraints, which I think will be very familiar to some and probably new to others … So, the Go generics PQ should still require some constraints on elements, not ’any’thing will work. I’ve really enjoyed constraints in languages and it’s not quite natural in C++/Java, but Go’s interfaces already do some ‘constraint’ work conceptually and can be used as constraints in Go’s generics syntax. I’m interested to see how this plays out.

[jacobvosmaer]

>not necessarily much safer than void*

You can cast void* to anything you want. With interface{} you get a type check, either through an assertion or a panic. That is a big difference in safety.

[xh-dude]

Fair point. Maybe there are contrived cases that can get nasty (an interface{}-typed variable boxing a function is possible, not so with any non-empty interface ), but in practice the pathology would be ‘panic’ more than ‘here are the keys to the exploit kingdom’, if this is what you were thinking.

I was thinking more about silence where someone expected a greater degree of compile-time type safety than they really had, or relatedly e.g. the subtleties in JSON encoding / decoding where there is silent data corruption that could fall through the cracks - mostly I feel like I avoid these things by not using interface{}; I certainly did not grasp that without some experience with the language.

[pjmlp]

I also wrote hundreds of stuff from 1986 up to 1994, my first experience with generics, on Turbo C++ for Windows 3.1.

Doesn't mean many of us want to keep living on that world.

I advise reading books like "From Mathematics to Generic Programming"