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Comment by dimgl | Hacker News Reader

I have yet to find one practical application for generics in the apps I've built in Go.

And I had yet to find a single practical application for closures, right up until the moment I started using Ruby (and later, Rust).

Turns out that they’re so useful in practice that they’ve been bolted on to—as far as I can tell—nearly every language in widespread use today. None of these languages “needed” such an improvement. Billions of lines of Java and C# were written without this feature. And yet today it would be virtually unthinkable to release a language without them.

I feel like closures are a consequence of having functions as first class citizens, so it's not exactly a direct comparison. But I guess I see your point.

That's crazy. I've seen people implement templating of go files to support generics in Go because it's serves a valuable purpose.

Safety! Generics allow you to get [theorems for free](https://ecee.colorado.edu/ecen5533/fall11/reading/free.pdf), so generics make certain classes of error extremely hard to make.

Every project I’ve written so far in golang could benefit from generics.

but what is the benefit? How does your code change. Generics are a tail abstraction. Its the last abstraction that you are able to make to your code to reduce boilerplate. This usually means that is the least useful and in generics specific case the boiler place it reduces is minimal.

Its lack of impact is why I dont really care about the subject. Adding or removing generics to a project matters little. So why bother complaining. The class creation and encapsulation choices are much more impactful to future code edits.

Go strongly discourages you from making extremely useful abstractions over types early on in your design. You don't just write things the same way and remove boilerplate with generics you can exploit more symmetries.

The benefit is that you can remove a lot of duplicate code that does exactly the same, except the type it operates on. The blogpost talks about the Reverse function.

Especially when you need to make changes, (fix bugs, performance improvements, etc), if you have dedicated functions for these, it takes effort to keep them (plus tests) in sync.

If you don't see any issue with this duplication, then I can see that generics don't add a lot.

its just not that much code usually. I would like to see an example of this "a lot of duplicate code" scenario. Most code sharing is done by super classes. Generics seem more like a syntactic sugar added to type sharing that interfaces already allow.

Have a look at viper.

There is research showing that number of bugs is a function of lines of code. As in, you can be overall better or worse with the implementation, but the more code you write, the more mistakes you'll make. Removing almost-duplicated code helps with this metric, especially when you operate on data structures ripe for off-by-one errors.

My experience from scala is that the use of generics is not an afterthought, not a boilerplate abstraction. They’re come in handy naturally when one knows how to use them, and it is not rocket science.

The real benefit of generics. They enable composability. The complete scala collections library is the best example of that. The benefit is non-obvious on a single function level, a complete program is another story.

It’s, of course, possible to to achieve something like this with golang and interface{}. I don’t mind working with it, all the type switches and what not make feel like a proper tinkerer! What is actually happening:, I’m wasting my time, the compiler already knows all the types. It can figure things out for me. Of course, a sound type system is then needed.

The types switches are error prone, it’s like working with java.lang.Object everywhere. And if I can avoid all these “GetX” functions, where X is “String”, “Int”, “Int32”, “Int64” and so on, even better. Just look at viper, it would be so clean and lightweight with generics.

> Generics are a tail abstraction. Its the last abstraction that you are able to make to your code to reduce boilerplate. This usually means that is the least useful and in generics specific case the boiler place it reduces is minimal.

This is absolute and utter delusional nonsense.

If the std lib had functions that mapped to the "Slice Tricks"[0], like virtually every other language, I'd use them constantly. Sure I wouldn't write generic functions all that much, but calling generic code I would do every day and it would be a serious ergonomic, correctness, and readability improvement to have named functions for very common patterns like the slice tricks.

0: https://github.com/golang/go/wiki/SliceTricks

Right, I see this as the biggest benefit.

Go already has generic built-in maps, channels and slices, so clearly those generic types are useful.

If what I actually want is a multiset, say, it would be great to have a standard library class that looks and behaves similarly to map except it’s a multiset, rather than just having to use map and do all the little 1- and 2-line boilerplate tricks for the multiset operations. I can write shorter code that more clearly expresses my intentions, and reduce the risk of stupid little bugs in the boilerplate.

Generics are more for developing reusable libraries than single applications.

I see you program in Blub (http://www.paulgraham.com/avg.html).

If you've never used a screwdriver, all you can say about screws is that they make crappy nails.

You've never used a data-structure other than the built in maps and slices?

If you're writing loops that build up some accumulator, you could use generics. Even if you don't see that.

You could use generics for that kind of code, but that doesn’t necessarily mean you need them.

If you’re thinking of functional stream operators, many people think plain imperative iteration is easier to write (and easier to read).

By that logic, there's nothing you _need_ generics for.

That's because you write a particular kind of program. Notice that there are no good ORMs or numerical libraries. Both of these are use cases for generics. Of course it doesn't help that the go community is convinced that ORMs are evil (which is just posthoc rationalization for being unable to write one).

Developers think ORMs are evil because they've had horrible experiences with ORMs in general. I'm one of them. The only ORM that I enjoyed using was Dapper, and it's barely an ORM.

Dapper really is such a weird edge case. You still write all the sql, all it does is the conversion from a type to the input parameters and the returned rows into objects where the row names match the parameters of the class. Frankly I feel like that's the right way to build ORMs in all languages that have the facilities to manage it (and maybe those that don't you pass in a function pointer to do the dumping of rows into type for you)

The sqlx package is a similar Go wrapper around SQL. Very handy for scanning into structs.

What sort of horrible experiences have you actually had with ORMs? Every time I've used one it's been an absolute joy, I hate repeating myself in my DB, in SQL, in mapping code and again in application code. The main thing I see people complaining about is performance edgecases, but for small and mid scale applications these can never take away the massive DRY principle gain good ORMs provide.

And almost every usage of Dapper relies heavily on generics.

There's no denying most C# code makes heavy use of generics, but we've deviated from the actual topic. C# is not Go. Far from it.

I'm not advocating for bringing a Dapper-like library to Go. I'm pretty happy with the solutions we have right now to map data coming from a SQL database into structs in Go. I'm commenting specifically on the argument that Go developers don't like ORMs.

> Of course it doesn't help that the go community is convinced that ORMs are evil (which is just posthoc rationalization for being unable to write one).

Yep. I held this opinion before Go came out, only because I couldn't write an ORM in Go.

i said the go community - not the developer community. you couldn't have had that opinion as a go user before go came out.

But I do still hold that opinion now as a go user. I'm saying I didn't develop it as a result of not being able to write/use an ORM.

Your wholesale dismissal of all go users that don't use ORMs is what I object to. There are a laundry list of reasons to not use them, simplicity being the largest in my eyes. If you're working with simple queries on a small number of tables/views/etc, there's really no reason to bring in a big heavy ORM.

As your usage scales that choice might change, but until then just do the simplest thing that has correct behavior and minimal magic involved.

“I can see the value so those that can’t are inferior.”

You basically just post hoc rationalized their indifference for ORMs by making them sound incompetent

As if there are no other arguments for avoiding them that perhaps seem valuable to people that are not you?

It sounds reasonable to me you conjured the hot take, acknowledged it was post hoc rationalization on your part, but posted anyway, projecting your capacity for after the fact rationalizing onto ORM haters in the Go community.

The point wasn't that Go programmers are too incompetent to implement an ORM, it's that they are actually unable to given the limitations of the language.

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