ALIEN: Abstractions, Languages, and Implementation Techniques That Cross the Program/Query Divide

数据库语言非常适合以声明式的方式描述大型数据集上的查询和操作，以及强大的优化，从而有效执行这些操作。另一方面，编程语言在通用性、抽象性和低级优化方面表现出色。该项目的目标是系统地将思想和技术从数据库语言转移到编程语言，反之亦然，其动机是观察到这两个研究社区中的许多当前趋势可以被视为“羡慕的偷窥”。“一方面，我们希望将标准数据库技术，如声明式查询，查询优化，索引和增量视图维护引入编程语言世界。这是具有挑战性的，需要修改和推广现有的技术，以考虑到更通用的编程模型的通用语言。另一方面，我们希望通过从通用（函数）语言中提取、分析和实现技术来丰富数据库语言。更具体地说，我们希望通过支持代数数据类型、高阶函数和泛型编程来提高数据库语言的表达能力。我们希望使用分析和实现技术，如程序切片，扁平化和去功能化，以提高数据库程序的分析和有效执行。在这两种情况下，我们的目标是不修改现有的编程或数据库语言，而是使用嵌入或编译技术，将这些新技术结合到现有的，经过验证的技术之上。我们的目标是建立一个低障碍，在实际应用中采用我们的技术。这个项目的最后一步是定义一种具有两种实现的表达性编程语言：一种编译为标准数据库系统，另一种嵌入（或编译为）函数式编程语言。有了这种新的测试平台语言，就有可能跨越技术障碍重用库和编程技术，并动态地改变数据库和通用主机之间的程序功能划分。

Database languages are well-suited to describe queries and operations on large data sets in a declarative way together with powerful optimizations that lead to efficient execution of those operations. Programming languages, on the other hand, excel in generality, abstraction, and low-level optimizations. The goal of this project is a systematic transfer of ideas and technologies from database languages to programming languages and vice versa, motivated by the observation that many current trends in these two research communities can be seen as an "envious peek over the fence."On one hand, we want to bring standard database techniques like declarative queries, query optimization, indexing, and incremental view maintenance to the programming language world. This is challenging and requires modifications to and generalizations of the existing techniques to account for the more general programming model of general-purpose languages. On the other hand, we want to enrich database languages with abstractions, analyses, and implementation techniques from general-purpose (functional) languages. More specifically, we want to increase the expressiveness of database languages with support for algebraic data types, higher-order functions, and generic programming. We want to use analysis and implementation techniques like program slicing, flattening, and defunctionalization to improve the analysis and efficient execution of database programs.In both cases, we aim to not modify existing programming- or database languages but rather use embedding or compilation techniques to incorporate those new techniques on top of the existing, proven technology. The goal is to establish a low barrier to adopt our techniques in practical applications. The final step in this project is the definition of one expressive programming language with two implementations: one that compiles to standard database system, and one that is embedded in (or compiled to) a functional programming language. With this new testbed language it will be possible to reuse libraries and programming techniques across the technology barrier, and to change the division of program functionality between the database and the general-purpose host on-the-fly.