Cultivating trees - an essay in APL2

Abstract

General arrays and the each operator allow tree-structures to be modelled in ways which have not hitherto been possible in any programming language. There are many algorithms in mathematics associated with tree-structures, which suggests that a whole new collection of relevant idioms and techniques will evolve. This paper is intended to illustrate ways in which the concepts of APL2 match those which arise in studying trees. After an introductory overview addressed to those who are unfamiliar with the basic notions of general arrays the discussion is developed through a set of 6 problems, which appear between them to raise many of the more important considerations involved.