Summary of flora2: Programming with Flora

LORA-2 is a sophisticated object-oriented knowledge base language and application development platform. It is implemented as a set of run-time libraries and a compiler that translates a unified language of F-logic [11], HiLog [7], and Transaction Logic [4,3] into tabled Prolog code.

Applications of LORA-2 include intelligent agents, Semantic Web, ontology management, integration of information, and others.

The programming language supported by LORA-2 is a dialect of F-logic with numerous extensions, which include a natural way to do meta-programming in the style of HiLog and logical updates in the style of Transaction Logic. LORA-2 was designed with extensibility and flexibility in mind, and it provides strong support for modular software design through its unique feature of dynamic modules. Other extensions, such as the versatile syntax of FLORID path expressions, are borrowed from FLORID, a C++-based F-logic system developed at Freiburg University.^11.1Extensions aside, the syntax of LORA-2 differs in many important ways from FLORID, from the original version of F-logic, as described in [11], and from an earlier implementation of $\cal {F}$LORA. These syntactic changes were needed in order to bring the syntax of LORA-2 closer to that of Prolog and make it possible to include simple Prolog programs into LORA-2 programs without choking the compiler. Other syntactic deviations from the original F-logic syntax are a direct consequence of the added support for HiLog, which obviates the need for the ``@'' sign in method invocations (this sign is now used to denote calls to LORA-2 modules).

LORA-2 is distributed in two ways. First, it is part of the official distribution of XSB and thus is installed together with XSB. Second, a more up-to-date version of the system is available on LORA-2's Web site at

http://flora.sourceforge.net

These two versions can be installed at the same time and used independently (e.g., if you want to keep abreast with the development of LORA-2 or if a newer version was released in-between the releases of XSB). The installation instructions are somewhat different in these two cases. Here we only describe the process of configuring the version LORA-2 included with XSB.