1991 年 6 巻 5 号 p. 690-700
We have implemented an amalgamated language, AMLOG which has integrated the features of logic and functional programming languages. The programmer can write programs more naturally in the amalgamated language. However AMLOG in its primitive form doesn't have a good debugging environment. The AMLOG has a tracer for debugging which gives programmers a trace of the execution steps. But the tracer output does not reflect the execution model of AMLOG, and is difficult to understand. In this paper, we propose a three-layer model which is the execution model of AMLOG. A block of execution process is represented by a box. The flow of execution, e. g. backtracking and retrying, is represented by arrows and the arrangement of boxes. We have implemented an execution monitor which is based on the three-layer model, using bitmap display. The monitor displays the execution graphically in a direct fashion. By using the monitor, a programmer can easily follow the execution flow and is able to carry out debugging in a top down style.