LWN: Comments on "What's coming in Go 1.18"

What's coming in Go 1.18

blancogrande — Fri, 11 Feb 2022 17:09:39 +0000

I'm as excited about workspaces as I am about generics. Anyone using a 'monorepo' style development where multiple applications share libraries within the repo will be happy.

What's coming in Go 1.18

tsavola — Wed, 09 Feb 2022 13:19:28 +0000

constraints.Ordered was supposed to be shipped in the standard library (I guess it will be added in a later release). Go doesn't support operator overloading, so only primitive types (and ~primitive types) can have the < operator.

For generic code invoking methods, you can define interfaces with methods - you don't have to list concrete types.

What's coming in Go 1.18

Cyberax — Wed, 09 Feb 2022 12:14:48 +0000

One other change that is often overlooked in 1.18 announcements is multi-module workspaces: https://go.googlesource.com/proposal/+/master/design/4571...

This _finally_ allows to do sane local development with multiple modules, so that you don't accidentally commit your "replace" directives in "go.mod".

What's coming in Go 1.18

jmaa — Wed, 09 Feb 2022 11:30:10 +0000

I _think_ you can define method interfaces, which should allow full generics, but the example I found of this is a year old. [1] The linked generics tutorial doesn't mention them, so who knows.

[1]: https://www.freecodecamp.org/news/generics-in-golang/

What's coming in Go 1.18

taladar — Wed, 09 Feb 2022 08:45:41 +0000

> func min(x float32, y float32) float32 {
> if x < y {
> return x
> }
> return y
> }

> type ordered interface {
> float32 | float64 | int
> }
> func min[T ordered](x T, y T) T {
> if x < y {
> return x
> }
> return y
> }

That looks like it is significantly less expressive than proper generics with open traits/type classes/interfaces/...

Can you really only specify a closed, one-time list without being able to add new types to it later?

What's coming in Go 1.18

Cyberax — Tue, 08 Feb 2022 23:04:25 +0000

One other significant addition: "~" operator for constraints. You can now write: "func min[T ~float32 | ~float64 | ~int](x T, y T) T" meaning that T is a type that behaves like float32, float64 or int.