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I haven't used Go but I'm curious, how do core data structures like hash maps work without generics? Does everyone just roll their own for their particular use-

by _bxg1 6y ago

I haven't used Go but I'm curious, how do core data structures like hash maps work without generics? Does everyone just roll their own for their particular use-case?

meditative 6y ago
> how do core data structures like hash maps work without generics blessed implementations inside the language, slices, maps and channels are built in generics. sync.Map is what the standard library version looks like. It loses type safety. https://golang.org/pkg/sync/#Map https://golang.org/pkg/sync/#Map
- echlebek 6y ago
  I'm looking forward to seeing these types of libraries improve with generics. It's notably more work to use these data structures, even if they are used rarely.
shirro 6y ago
Go cheats with some built-in generic types. So you can declare a hashtable as a map of any comparable type to any other type. But yes you typically have to implement things yourself for more complex cases so that does limit the sorts of libraries that are available and the way you write programs.
- erik_seaberg 6y ago
  Unfortunately "comparable" is not an interface, and the default implementation (which you can't opt out of) sometimes panics.
  - pjmlp 6y ago
    Like in everything Go, you opt out by using a clever hack like having a nameless non comparable field in the struct. Oh yeah.
echlebek 6y ago
The built-in types map, chan, array, and slice take type parameters, and they are usually sufficient for doing whatever you need to do. It's incredibly great that, generally speaking, if I'm looking at Go code, the only kind of hashtable there can possibly be is the Go map data structure. The only kind of blocking queue there can possibly be is the Go chan data structure. You will never see a LinkedTreeDeque or whatever other bizarre concoction someone might come up with. And people don't feel obligated to make every API an iterator of some kind. Go makes being generics architecture astronautics impossible, and I really love that about it. Perhaps that makes me basic, but I am basic and happy.
- jfkebwjsbx 6y ago
  A lot of software needs specialized data structures to perform their job. They are not "bizarre concoctions".
- throw_m239339 6y ago
  > The built-in types map, chan, array, and slice take type parameters, and they are usually sufficient for doing whatever you need to do. They are so sufficient you need to learn all these tricks by heart in order to do basic operations on slices: https://github.com/golang/go/wiki/SliceTricks https://github.com/golang/go/wiki/SliceTricks

by _bxg1 6y ago

I haven't used Go but I'm curious, how do core data structures like hash maps work without generics? Does everyone just roll their own for their particular use-case?

meditative 6y ago

> how do core data structures like hash maps work without generics blessed implementations inside the language, slices, maps and channels are built in generics. sync.Map is what the standard library version looks like. It loses type safety. https://golang.org/pkg/sync/#Map https://golang.org/pkg/sync/#Map

echlebek 6y ago
I'm looking forward to seeing these types of libraries improve with generics. It's notably more work to use these data structures, even if they are used rarely.

shirro 6y ago

Go cheats with some built-in generic types. So you can declare a hashtable as a map of any comparable type to any other type. But yes you typically have to implement things yourself for more complex cases so that does limit the sorts of libraries that are available and the way you write programs.

erik_seaberg 6y ago
Unfortunately "comparable" is not an interface, and the default implementation (which you can't opt out of) sometimes panics.
- pjmlp 6y ago
  Like in everything Go, you opt out by using a clever hack like having a nameless non comparable field in the struct. Oh yeah.

echlebek 6y ago

The built-in types map, chan, array, and slice take type parameters, and they are usually sufficient for doing whatever you need to do. It's incredibly great that, generally speaking, if I'm looking at Go code, the only kind of hashtable there can possibly be is the Go map data structure. The only kind of blocking queue there can possibly be is the Go chan data structure. You will never see a LinkedTreeDeque or whatever other bizarre concoction someone might come up with. And people don't feel obligated to make every API an iterator of some kind. Go makes being generics architecture astronautics impossible, and I really love that about it. Perhaps that makes me basic, but I am basic and happy.

jfkebwjsbx 6y ago
A lot of software needs specialized data structures to perform their job. They are not "bizarre concoctions".
throw_m239339 6y ago
> The built-in types map, chan, array, and slice take type parameters, and they are usually sufficient for doing whatever you need to do. They are so sufficient you need to learn all these tricks by heart in order to do basic operations on slices: https://github.com/golang/go/wiki/SliceTricks https://github.com/golang/go/wiki/SliceTricks