带有通用项的SwiftArray扩展

我正在使用Swift 3.1并有一些通用的结构:

struct Section {
    let info: InfoT?
    let items: [ItemsT]
}

并希望使用自定义方法对此泛型类型的元素进行数组扩展:

extension Array where Element == Section {
    // Just dummy example function:
    func debugDummy() {
        for section in self {
            let info = section.info
            print("section info: \(info).")
            for item in section.items {
                print("item: \(item).")
            }
        }
    }
}

这给了我编译错误:

error: using 'Equatable' as a concrete type conforming to protocol 'Equatable' is not supported
extension Array where Element == Section {
                                 ^

error: GenericsListPlayground.playground:6:24: error: value of type 'Element' has no member 'info'
            let info = section.info
                       ^~~~~~~ ~~~~

error: GenericsListPlayground.playground:8:25: error: value of type 'Element' has no member 'items'
            for item in section.items {
                        ^~~~~~~ ~~~~~

如何正确申报此类延期？我已尝试过几种变体来声明此扩展名,例如:

extension Array where Element == Section (no arguments)

生产:

error: reference to generic type 'Section' requires arguments in <...>

等...他们都不想编译.

试试这个:

import Foundation

protocol Section {
    associatedtype InfoT: Equatable
    associatedtype ItemsT: Equatable
    var info: InfoT? { get }
    var items: [ItemsT] { get }
}

extension Array where Element: Section {
    // Just dummy example function:
    func debugDummy() {
        for section in self {
            let info = section.info
            print("section info: \(String(describing: info)).")
            for item in section.items {
                print("item: \(item).")
            }
        }
    }
}