Some professional programmers find it difficult to accept that APL handles complicated data without loops and counts. They're unused to the APL concept of a 'workspace' in which data and code rub shoulders. They fret about 'type-safety' and the fact that APL lets you do what you want. The functions written by the user behave neither like programs nor subroutines - what are they?
If you haven't programmed before, none of these questions will bother you. You'll accept the way APL does things as natural and convenient. For this reason, APL has traditionally been used by people who are not primarily computer programmers, but who need to write quite sophisticated programs in the course of their work or research - actuaries, engineers, statisticians, biologists, financial analysts, market researchers, and so on.