Web and Media group, VU University Amsterdam,

Abstract. SWI-Prolog version 7 extends the Prolog language as a general pur-pose programming language that can be used as ‘glue ’ between components writ-ten in different languages. Taking this role rather than that of a domain specific language (DSL) inside other IT components has always been the design objective of SWI-Prolog as illustrated by XPCE (its object oriented communication to the OS and graphics), the HTTP server library and the many interfaces to external systems and file formats. In recent years, we started extending the language it-self, notably to accommodate expressing syntactic constructs of other languages such a HTML and JavaScript. This resulted in an extended notion of operators and quasi quotations. SWI-Prolog version 7 takes this one step further by extend-ing the primitive data types of Prolog. This article describes and motivates these extensions.