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Yes, but `Copy` is a trait, not a type. Traits can be used as types but they're ... different.
by Manishearth 11y ago
Yes, but `Copy` is a trait, not a type. Traits can be used as types but they're ... different.
- madez 11y agoI'm longing for formal definitions of type and trait, to see the exact difference.
- Dewie3 11y agoI've been wondering about the same thing recently too. Meanwhile, there is an article that explains how Haskell typeclasses[1] are implemented, or how they conceptually work: https://www.fpcomplete.com/user/jfischoff/instances-and-dictionaries https://www.fpcomplete.com/user/jfischoff/instances-and-dict... [1] I guess close enough analog to Rust traits.
- Manishearth 11y agoTypes are types. Let's take a type system with generics but no single inheritance. Traits are properties that types can have, like Java interfaces though more powerful. Many traits can be used as types to form a vtable dispatch. For example, Box<Send> uses the trait `Send` here as a type. Objects of type `Send` are "unsized" and must be held behind a pointer (which becomes a fat pointer).
- Dewie3 11y ago> Traits are properties that types can have, like Java interfaces though more powerful. The GP asked about formal definitions. So I think they want something more precise than that.
- Manishearth 11y agoI know, I was just clarifying my original statement :)