Reflection is a wide-ranging concept that has been studied independently in many different areas of science in general, and computer science in particular. Even in the sub-area of programming languages, it has been applied to different paradigms, especially the logic, functional and objectoriented ones. Partly because of different past influences, but also because researchers in these communities scarcely talk to each others, concepts have evolved separately, sometimes to the point where it is hard for people in one community to recognize similarities in the work of others, not to speak about cross-fertilization among them. In this paper, we propose a synthesis covering mainly the application of computation reflection to programming languages. We compare the different approaches and try to identify similar concepts hidden behind different names or constructs. We also point out the different emphasis that has been given to different concepts in each of them. We do not claim neither comp...

. A meta-level extension of a logic programming language is presented. The resulting language, called 'LOG (read quote-log), provides meta-programming facilities similar to those of Prolog while preserving a declarative logical semantics. It also offers new meta-programming opportunities as compared with Prolog due to its ability to treat whole programs, i.e. sequences of clauses, as data objects. The extension basically consists in defining a suitable naming scheme. It associates two different but related meta-representations with every syntactic object of the language, from characters to programs. The choice of the double metarepresentation is motivated by both the user and the implementation viewpoints. All Prolog built-in meta-predicates can be redefined as 'LOG programs by exploiting the new naming scheme. Then some syntactic sugar is added to make the language more concrete. Some examples are given, in particular to show the ability of the language to deal with programs as data....