高阶函数与面向对象继承的比较

纯虚类

typedef: transformX: (Value) -> U

func transformFun(:value:Value) -> U

基类：

public func map<T>(_ transform: (Element) throws -> T) rethrows -> [T]

public func map<U>(transformX) -> Result<U, Error> {

return flatMap { .success(transform($0)) }

}

public func flatMap<U>(_ transform: (Value) -> Result<U, Error>) -> Result<U, Error> {

return analysis(

ifSuccess: transform,

ifFailure: Result<U, Error>.failure)

}

子类：

flatMap { .success(transform($0)) }

let string = typedData.map {

                    return "\($0.name) : \($0.value.string)"

                }