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Comment by 9rx | Hacker News Reader

> Lack of proper enums is hurting so much I can't describe it.

Do you mean sum types? That is not a case of them not being "proper", though. They simply do not exist as a feature at all.

Go's enums function pretty much like enums in every single other language under the sun. If anything, Go enums are more advanced than most languages, allowing things like bit shifts. But at the heart of it all, it's all just the same. Here are enum implementations in both Go and Rust:

[Go] https://github.com/golang/go/blob/f18d046568496dd331657df4ba...

[Rust] https://github.com/rust-lang/rust/blob/40daf23eeb711dadf140b...

While Go leans on the enum value produced by `range` to act as the language's enumerator, while Rust performs explicit incrementing to produce the enumerator, the outcome is no different — effectively nothing more than [n=0, n++]. Which stands to reason as that's literally, as echoed by the dictionary, what an enum is.

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Go doesn't even classic type-safe integer-value enums like in C++ or enums.

Yes, you can emulate this style of enums by using iota to start a self-incrementing list of integer constants. But that's not what any language (except for C) has ever meant by "enum".

Enums are generally assumed to be type-safe and namespaced. But in Go, they are neither:

  type Color int

  const (
      Red Color = iota
      Green
      Blue
   )

   func show(color Color) {
       fmt.Printf("State: %v", color)
   }

   fun main() {
       show(Red)
       show(6)
   }

There is no namespacing, no way to — well — enumerate all the members of the enum, no way to convert the enum value to or from a string (without code-genreation tools like stringer), and the worst "feature" of all is that enums are just integers that can freely receive incorrect values.

If you want to admire a cool hack that you can show off to your friends, then yeah, iota is a pretty neat trick. But as a language feature it's just a ugly and awkward footgun. Being able to auto-increment powers of two is a very small consolation prize for all of that (and something you can easily achieve in Rust anyway with any[1] number[2] of crates[3]).

[1] https://crates.io/crates/enumflags2

[2] https://crates.io/crates/bitmask-enum

[3] https://crates.io/crates/modular-bitfield

> Go doesn't even classic type-safe integer-value enums like in C++ or enums.

Sure, but now you're getting into the topic of types. Enums produce values. Besides, Go isn't really even intended to be a statically-typed language in the first place. It was explicitly told when it was released that they wanted it to be like a dynamically-typed language, but with statically-typed performance.

If you want to have an honest conversation, what other dynamically-typed languages support type-safe "enums"?

> But that's not what any language (except for C) has ever meant by "enum".

Except all the others. Why would a enum when used when looping over an array have a completely different definition? It wouldn't, of course. Enums are called what they are in a language because they actually use enums in the implementation, as highlighted in both the Go and Rust codebases above.

Many languages couple enums with sum types to greater effect, but certainly not all. C is one, but even Typescript, arguably the most type-intensive language in common use, also went with "raw" enums like Go.

It's not about 'range', and like you said enum and sum types are tied concepts in other languages, and yes I was talking about sum types.

Even without sum types, there is a common pattern of defining a new type and const-defining the possible values that is a clear workaround on the lack of an 'enum' keyword.

Maybe because the compiler can't be sure that those const values are all the possible values of the type, we can't have things like enforcing exhaustive switches on this "enum", and that is left to the linter at best.

Default-zero initialization is always valid too, which can leave you with an "enum" value that is not present in the const definitions (not everything starts on iota, iota does not mean 0).

It's a hack, it became a pattern. It still is not a proper (or even basic) enum even without sum types.

> It's not about 'range'

It is to the extent that it helps explain what an enum is, and why we call the language feature what we do. Python makes this even more apparent as you explicitly have to call out that you want the enum instead of it always being there like in Go:

    for i, v in enumerate(array):
       # ...

In case I'm not being clear, an array enumerator like in the above code is not the same as a language enumerator, but an array enumerator (or something similar in concept) is how language enumerators are implemented. That is why language enumerators got the name they did.

> It still is not a proper (or even basic) enum even without sum types.

It most certainly is "proper". In fact, you could argue that most other languages are the ones that are lacking. Go's enums support things like bit shifts, which is unusual in other languages. Perhaps it is those other languages that aren't "proper"?

But, to be sure, it's not sum types. That is certain. If you want sum types you are going to have to look elsewhere. Go made it quite clear from the beginning that it wanted to be a "dynamically-typed language with statically-typed performance", accepting minimal static type capability in order to support the performance need.

There is definitely a place for languages with more advanced type systems, but there are already plenty of them! Many considerably older than Go. Haskell has decades on Go. Go was decidedly created to fill in the niche of "Python, but faster", which wasn't well served at the time. Creating another Haskell would have been silly and pointless; but another addition to the long list of obscure languages serving no purpose.

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