5 ms·

Since 1.18 was released it's now trivial to implement compile-time (safe) 'sum types' in Go. They're fully supported. It's about 300loc to implement and then

Since 1.18 was released it's now trivial to implement compile-time (safe) 'sum types' in Go. They're fully supported. It's about 300loc to implement and then sum types can be defined declaratively just like any other type (and without any boilerplate). There hasn't been any fanfare about this capability because it doesn't require any special syntax or new keywords. Just know that the suggestion that "Go 1.18+ doesn't support sum types and/or enums", is very wrong.

Strum355 4y ago
Not going to link it anywhere? I have some doubts given how widely it wouldve been shared if the claim is actually true, and your not linking of an example kinda just furthers that
- Splizard 4y ago
  Sum types: https://go.dev/play/p/R7Bhy2LDmde https://go.dev/play/p/R7Bhy2LDmde Enums: https://go.dev/play/p/MnbmE0B3sSE https://go.dev/play/p/MnbmE0B3sSE Here you go.
  - esprehn 4y ago
    That code appears to be using reflection to build up runtime tables? https://github.com/qlova/tech/blob/c6379c9c32e5b7b2973bc02ba935765a4aefa514/sum/sum.go#L88 https://github.com/qlova/tech/blob/c6379c9c32e5b7b2973bc02ba... https://github.com/qlova/tech/blob/c6379c9c32e5b7b2973bc02ba935765a4aefa514/sum/sum.go#L177 https://github.com/qlova/tech/blob/c6379c9c32e5b7b2973bc02ba... That's a big difference from other languages where this is all handled at compile time.
  - suremarc 4y ago
    This is cool, but it doesn't seem like Switch is implemented for Int, and the use of runtime reflection limits the contexts in which this implementation can be used, compared to a language construct that gets compiled into efficient machine code. I wouldn't want this to be endemic in my codebase or my dependencies.
    - Splizard 4y ago
      Enum supports an exhaustive Switch as well, here's an example based on the blog post: https://go.dev/play/p/Ef78vLyw33g https://go.dev/play/p/Ef78vLyw33g
  - arriu 4y ago
    Is it just me or is the syntax on these worse than the issues it’s solving?
    - masklinn 4y ago
      It's not you, this is a worse version of std::variant, which isn't exactly great in the first place.

Strum355 4y ago

Not going to link it anywhere? I have some doubts given how widely it wouldve been shared if the claim is actually true, and your not linking of an example kinda just furthers that

Splizard 4y ago
Sum types: https://go.dev/play/p/R7Bhy2LDmde https://go.dev/play/p/R7Bhy2LDmde Enums: https://go.dev/play/p/MnbmE0B3sSE https://go.dev/play/p/MnbmE0B3sSE Here you go.
- esprehn 4y ago
  That code appears to be using reflection to build up runtime tables? https://github.com/qlova/tech/blob/c6379c9c32e5b7b2973bc02ba935765a4aefa514/sum/sum.go#L88 https://github.com/qlova/tech/blob/c6379c9c32e5b7b2973bc02ba... https://github.com/qlova/tech/blob/c6379c9c32e5b7b2973bc02ba935765a4aefa514/sum/sum.go#L177 https://github.com/qlova/tech/blob/c6379c9c32e5b7b2973bc02ba... That's a big difference from other languages where this is all handled at compile time.
- suremarc 4y ago
  This is cool, but it doesn't seem like Switch is implemented for Int, and the use of runtime reflection limits the contexts in which this implementation can be used, compared to a language construct that gets compiled into efficient machine code. I wouldn't want this to be endemic in my codebase or my dependencies.
  - Splizard 4y ago
    Enum supports an exhaustive Switch as well, here's an example based on the blog post: https://go.dev/play/p/Ef78vLyw33g https://go.dev/play/p/Ef78vLyw33g
- arriu 4y ago
  Is it just me or is the syntax on these worse than the issues it’s solving?
  - masklinn 4y ago
    It's not you, this is a worse version of std::variant, which isn't exactly great in the first place.