Tracing the evaluation of APL expressions
John Sigle · ACM SIGAPL APL Quote Quad · 1985
The ability to trace each step in the evaluation of an APL expression is useful for debugging and improving APL code as well as for teaching APL. This facility can be provided by the APL interpreter, however, it is not clear what form of display is most suitable for this purpose. In this paper three alternate forms of display are described, illustrated and compared. The question of how this capability should be invoked is also addressed.