Go 1.23 stabilised range over function iterators, a feature that had been in the rangefunc experiment since 1.22. It’s the most significant addition to the range statement since channels were added. The reaction has been mixed: people who needed it find it elegant; people who didn’t need it find it confusing. Both reactions are reasonable. Here’s what it actually does and where it belongs. ...
Go 1.18 was still months away when the design was finalised, but the proposal was public and we were already prototyping. After building several services at the European fintech firm with the experimental toolchain, the pattern of when generics help versus when they don’t was becoming clear. The answer is not “always use generics” or “avoid them.” It’s more specific than that. ...
Go had resisted generics for years. The arguments against were practical: generics complicate the language, they interact badly with Go’s interface system, and most cases where you want generics can be handled with interface composition or code generation. The arguments weren’t wrong. But the proposal that eventually shipped in Go 1.18 (2022) addressed a real gap — a gap that was producing either duplicated code or interface{} with runtime type assertions everywhere. Here’s what the proposal was solving. ...