Using APL to monitor APL

APL, both in the language and in system libraries, provides aids to the programmer which permit him to monitor and analyze the execution of his defined functions. If he couples the use of error messages with stop and trace control, he can converge upon function definitions which correctly perform his algorithms. If the writer is satisfied with the correctness of the results and now wishes to improve performance, he can invoke any of the workspace analysis routines in the library. These will reveal how the programs are linked together, how variable and label names are being used, and how efficient the functions are in the use of system time and space.