ECLiPSe has an efficient incremental compiler which compiles Prolog source into the instructions of an abstract machine and they are then executed by an emulator. The compiler is very fast, it compiles about 1000 lines/sec. on a Sun-4, and this makes the usual debugging cycle acceptably short. Unlike other Prolog systems, the ECLiPSe compiler generates code that can be used for debugging, so that no separate interpreter is necessary, and also the debugged code runs faster.
The ECLiPSe compiler is interactive and incremental, which means that Prolog programs are compiled during a ECLiPSe session directly into the Prolog database. ECLiPSe has no means to compile Prolog programs off-line, store the abstract code into a file and load the file during the Prolog session, however compiling a file in ECLiPSe
is as fast as loading the abstract code in other systems and so it makes it obsolete.