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The Internet Gets Logical

EXE Magazine

 

Visual Prolog version 5.0, from Prolog Development Center (PDC), contains compiler improvements, an enhanced development environment, Internet support, and a debugger (for the first time).

Changes to the compiler include the possibility to declare predicates as procedure, failure, erroneous, and multi – in addition to determ and nondeterm. This enables the compiler to check for dangerous fail conditions in procedural code. Unused local predicates and problematic automatic type conversions can be detected. There are new predicates for runtime error handling and the compiler now supports a concept of Objects and Classes. A new linker means programs can be built without the use of a C compiler.

As well as increased speed of compilation and linking, enhancements to the development environment include support for project sharing and source code control, with systems such as PVCS, MKS, and MS SourceSafe. Cursor positioning at the location of runtime errors has been added.

Over fifty new predicates have been added. They are concerned mainly with aspects of a GUI: for example, changing fonts, customising menus, loading icons, and storing print preferences.

The Internet support of Visual Prolog 5.0 is to facilitate the development of intelligent web sites – expert systems attached to homepages. They would be able to automate processes such as helping customers choose products. PDC anticipate applications for intelligent agents or data-mining, to help users navigate the volume of online information. As well as bindings to Sockets, there is FTP and HTTP support. Example programs illustrate communication with Java applets, and CGI and ISAPI support.

The debugger is a stand alone program for Win32 platforms. It is expected to be ported to OS/2 (but not to Win16 platforms).