Intensional sets are sets given by a property rather than by enumerating their elements. In previous work, we have proposed a decision procedure for a first-order logic language which provides Restricted Intensional Sets (RIS), i.e., a sub-class of intensional sets that are guaranteed to denote finite---though unbounded---sets. In this paper we show how RIS can be exploited as a convenient programming tool also in a conventional setting, namely, the imperative O-O language Java. We do this by considering a Java library, called JSetL, that integrates the notions of logical variable, (set) unification and constraints that are typical of constraint logic programming languages into the Java language. We show how JSetL is naturally extended to accommodate for RIS and RIS constraints, and how this extension can be exploited, on the one hand, to support a more declarative style of programming and, on the other hand, to effectively enhance the expressive power of the constraint language provided by the library.

中文翻译：

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使用 JSetL 在 Java 中使用内涵集进行声明式编程

内涵集是由属性给出的集合，而不是通过枚举它们的元素。在以前的工作中，我们为一阶逻辑语言提出了一个决策过程，它提供了受限内涵集（RIS），即一个内涵集的子类，它保证表示有限的——尽管是无界的——集. 在本文中，我们展示了如何将 RIS 用作一种方便的编程工具，也可以在常规设置中使用，即命令式 OO 语言 Java。我们通过考虑称为 JSetL 的 Java 库来实现这一点，该库将逻辑变量、（集合）统一和约束的概念集成到 Java 语言中，这些概念是约束逻辑编程语言的典型特征。我们展示了 JSetL 如何自然地扩展以适应 RIS 和 RIS 约束，以及如何利用这种扩展，一方面，