SHF: Small: Always-On Static and Dynamic Feedback

软件开发人员的目标是以低成本创建可靠的软件。可以帮助完成这项任务的两种工具是静态和动态分析工具。静态分析工具在不运行程序的情况下对程序源代码进行推理；一个广泛使用的例子是类型系统。动态分析工具在程序执行时观察程序；一个广泛使用的例子是测试。动态和静态反馈提供了互补的好处，两者都不占优势，并且在任何时候只有程序员知道哪一个是最有用的。不幸的是，当前的编程语言强加了过于严格的开发过程模型：它们要么喜欢静态工具，要么喜欢动态工具，这阻碍了程序员自由使用其他类型的工具。我们提出了一种新的方法，在这种方法中，开发人员总是能够获得即时的执行反馈，并且总是能够获得可靠的静态反馈。关键的更广泛的影响是允许开发人员以他们认为最自然和有效的方式工作，这将提高可靠性并降低成本。开发人员将创建比在支持动态分析的环境中创建的软件更可靠的软件。开发人员将比在支持静态分析的环境中工作得更快。众所周知，动态类型脚本语言和静态类型编程语言具有互补的优势。例如，脚本可以允许更快和更灵活的程序开发和修改，而编程语言可以生成更可靠和可维护的应用程序。我们的目标是为程序员提供脚本语言和编程语言的好处，以便程序员可以根据手头的任务在这两种范式之间来回切换。在我们的方法中，程序员可以通过健全的静态类型来查看和执行程序，也可以通过动态类型来查看和执行程序，而没有静态强加的限制。此外，程序员可以根据需要经常在这两个视图之间切换，或者可以同时使用它们，这取决于程序员当前的信息需求。在我们的方法中，程序员可以暂时禁用类型系统并测试代码，即使代码没有进行类型检查。执行代码时，就好像没有编写任何类型一样。类型错误（执行与声明的类型不一致）会被记录，但不会终止执行。如果测试失败，则可以检查记录的错误，如果测试成功，则可以延迟记录。此模式适用于诸如初始原型、改进接口、表示更改、库替换和探索性重构等任务。

Software developers aim to create reliable software at low cost. Two types of tools that help in this task are static and dynamic analysis tools.Static analysis tools reason about the program source code, without ever running the program; a widely-used example is type systems. Dynamic analysis tools observe the program as it executes; a widely-used example is testing. Dynamic and static feedback provide complementary benefits, neither one dominates the other, and at any moment only the programmer knows which one would be most useful. Unfortunately, current programming languages impose too rigid a model of the development process: they favor either static or dynamic tools, which prevents the programmer from freely using the other variety. We propose a new approach, in which the developer always has access to immediate execution feedback, and always has access to sound static feedback. The key broader impact is to permit developers to work the way they find most natural and effective, which will improve reliability and reduce cost. Developers will create software that is more reliable than that created in an environment that favors dynamic analysis.Developers will work faster than they can in an environment that favors static analysis.It is well-known that dynamically-typed scripting languages and statically-typed programming languages have complementary strengths. For example, scripting can permit faster and more flexible program development and modification, whereas programming languages can yield more reliable and maintainable applications. Our goal is to give programmers the benefits of both scripting languages and programming languages, so that a programmer can shift back and forth between the two paradigms depending on the task at hand. In our approach, a programmer can view and execute a program through the lens of sound static typing, or can view and execute a program through the lens of dynamic typing with no statically-imposed restrictions. Furthermore, the programmer can switch between these two views as often as desired, or can use them both simultaneously, depending on the programmer's current information needs. In our approach, a programmer may temporarily disable the type system and test the code, even if the code does not type-check. The code is executed as if no types had been written. Type errors (inconsistencies between the execution and the declared types) are logged but do not terminate execution. The logged errors can be examined if the test fails or deferred if the test succeeds. This mode is appropriate for tasks such as initial prototyping, evolving an interface, representation changes, library replacement, and exploratory refactoring.