Previous attempts to apply Halstead's software metrics to APL have led to inconsistent and counter-intuitive results. This work is a further investigation into the application of software metrics to APL to try to resolve some of the inconsistency. The effect of variations in the counting rules on values calculated for the software metrics was studied. These rules were used to analyze a set of programs from a previous study. In addition, a large number of APL programs from a university environment were analyzed. Evidence is presented that verifies that APL has a higher language level than any other common programming language previously studied. Counting monadic and dyadic uses of the same APL symbol as an instance of a different operator was found to have a significant effect on the language level calculated for APL. However, decomposing derived APL functions into separate operators did not seem to have a significant effect on language level.

In the last decade computer science has been struggling to establish it's independent identity, pressured on one side by those who refuse to admit the existence of any new sciences and on the other by those who see computer science as no more than the art of constructing computer programs.