SHF: Small: Foundations for User Interface Programming

超过三分之一的程序代码是用来实现用户界面的，而这些代码包含了更大部分的所有缺陷。这并不奇怪；用户界面代码很少可重用，当前基于事件处理的用户界面编程方法需要程序员管理大量的细节；太多的细节无法一致地产生正确和丰富的用户界面行为。所有计算机用户都会感受到这种影响：用户界面被卡住、行为不合逻辑、丢失信息、缺乏关键或有用的功能，或者只是令人困惑。其结果是用户沮丧和浪费努力，当汇总到所有用户时，这是一个非常大的成本，即使是一个用户，汇总到他或她的所有计算机使用时，也是巨大的成本。这个项目寻求用户界面编程方面的进步，研究一种声明性方法，其中用户界面的许多行为可以表示为软件库中编码的可重用算法。这极大地减少了应用程序程序员需要关心的细节；根本不需要特定于应用程序的“事件处理”代码。其目标是显著降低生产高质量用户界面的成本，并间接地通过更好的用户界面使我们与计算机的交互不那么令人沮丧和更有效率。所提出的声明式编程方法基于多路数据流约束系统，该系统被应用于对用户界面直接操纵的数据以及该数据中的依赖关系进行建模。该项目试图表明，一旦应用程序程序员指定了这样的约束系统并将其连接到用户界面的可视元素，界面的行为的大类可以从在约束系统上参数化的可重用算法中派生出来。此类行为的示例包括基于其他用户界面元素上的用户交互来更新元素的值、启用和禁用用户界面元素、通过并发执行由用户交互触发的计算来保持用户界面的最大响应、管理用户界面结构中的改变、以及正确地协调所有上述操作。

More than one-third of all program code exists to implement user interfaces and this code contains an even larger portion of all defects. This is no surprise; user interface code is seldom reusable and current event-handling-based approaches to user interface programming require programmers to manage a large number of details; too many to consistently produce correct and rich user interface behaviors. The impact is experienced by all computer users: user interfaces get stuck, behave illogically, lose information, lack crucial or useful functionality, or are simply confusing. The result is user frustration and wasted effort, a very significant cost when aggregated over all users, and significant even to one user when aggregated over all of his or her computer use. This project seeks advances in user interface programming, studying a declarative approach where many behaviors of user interfaces can be expressed as reusable algorithms encoded in software libraries. This drastically reduces the details that an application programmer needs to be concerned with; application-specific "event handling" code is not necessary at all. The goal is to significantly reduce the cost of producing high quality user interfaces, and, indirectly through better user interfaces, to make our interactions with computers less frustrating and more productive.The proposed declarative programming approach is based on multi-way data-flow constraint systems, which are applied to model the data directly manipulated by user interfaces and the dependencies within that data. The project seeks to show that once an application programmer specifies such a constraint system and connects it to the visual elements of a user interface, a large class of the interface's behavior can be derived from reusable algorithms parametrized over the constraint system. Examples of such behaviors include updating values of elements based on user interaction on other user interface elements, enabling and disabling user interface elements, keeping the user interface maximally responsive by concurrently executing computations triggered by users' interactions, managing changes in the structure of the user interface, and correctly orchestrating all of the above.