"Go was designed to address the problems faced in software development at Google, which led to a language that is not a breakthrough research language but is nonetheless an excellent tool for engineering large software projects"[0]
They go on to list some concrete points on the type of problems they are trying to solve:
- slow builds
- uncontrolled dependencies
- each programmer using a different subset of the language
- poor program understanding (code hard to read, poorly documented, and so on)
- duplication of effort
- cost of updates
- version skew
- difficulty of writing automatic tools
- cross-language builds
I might not agree with the way they value generics but to me, it does seem reasonable given their design vision and goals.
And I'm not buying the poor programmer understanding argument. Generics aren't that complex, they're just parameterized types. The fact that basic language libraries such as maps and slices cannot be implemented without them speak volumes about how fundamental they are when building abstractions.
My point is that most of the backpressure against generics seems to stem from perceived added complexity to the compiler and type system, and thats all. But I'm not convinced thats a valid argument. Truth be told, I'm not a language implementer. But I know that fast compilers and runtimes that implement generics exist, so I don't find the whole discussion believable.
Are you arguing that an implementation of generics in a programming language is free? (Whether it be performance or implementation complexity.) Because if not, then you admit there are trade offs. If there are trade offs, then it is conceivable that some circumstances (including programmer tastes) may lead to a valuation that is different from yours.
"Performance" of the compiler is a critical goal of the Go project. Could you point out for me an industrial strength compiler that supports a type system of your liking that can match the compilation speed of the Go compiler? (I can't think of one.) Because if not, then I'll have to invoke this: talk is cheap, show me the code.
I am.
Performance: if you replace all generics with interface{}, you get performance that is at better or equal to current Go code.
Implementation complexity: You could add some constraints to generics, for example only interface types can be used as generic parameters, and all uses of variables/methods/functions with generic types need to have generic parameters given. In that case, there's no complexity for code that doesn't use generics. Also, generics could actually be implemented as a preprocessor that would simply insert appropriate casts from/to interface{} at calls to generic methods. Since all variables/functions in Go are declared and have known types, you could of course go further and eliminate most generic parameter annotations.
That is incorrect. Using `interface{}` incurs a significant performance penalty at runtime because you end up boxing everything. For example, you cannot cast a `[]interface{}` to an arbitrary `[]A`.
In other words, no, `interface{}` is not `void*`, sorry. If it was, Go would not be memory safe. (See golang.org for their definition of memory safety. It is strictly superior to a language like C, but e.g., less than a language like Rust.)
AFAIK it's not possible to write generic Go code without `interface {}` (or, alternatively, duplicating the code for each type).
`interface{}` is very rarely used for writing "generic" code precisely because of its lack of type safety and performance implications. If you came up with a way to make it type safe without addressing performance, you've just implemented a generics scheme that will cause programs to be slower than they would be without generics (because people would start using them!).
In other words, the only "cost" of generics, thus, is the social cost (there is no purely technical cost). Here, it boils down to the philosophical/political freedom-vs-safety question, and I strongly incline towards freedom. Go does not. Go's position is, if not wrong, at least loosing, since programmers demonstrably are using work-arounds (`interface {}`) when they need generics.
I just got through telling you that this type of use is actively discouraged, so no, people aren't using it as often as you might think.
If you want generics, you've got to pay for it. The implementation you've suggested requires a runtime performance penalty to use generics. Therefore, you have not demonstrated that generics are free.
There are likely other issues that golang needs to solve that are much higher priority issues, and there are flexible, even scripted languages that can handle higher level logic problems and scale very well. I wouldn't really expect to have to use generics for most of the problems I would look to go as a first language for a given problem.
Of course all of the above said, I'm a node.js fan and really like what it has to offer. It just depends on your use cases. Go is a really clean language/platform with a lot in the box, that I do appreciate. I would be surprised if they didn't support generics for v2, if not before. But I can see why they would want to punt the issue while there are bigger problems and needs to address.
Specifically, the claim that "maps and slices" can replace the ability to write abstractions such as futures, promises, observables as well as generic function such as map, reduce etc comes off as either naive or disingenuous
Furthermore, the "cost" of these features seems overstated to me. A lot of languages and runtimes already implement generics without significant compile-time or run-time overhead - why is it that hard for Go to do that?