> To understand monads (of which ordinary lists are a good example), I do > think you need to understand the spirit in which category theory conduct > mathematical investigations. A very good/easy essay to read, which I highly > recommend is http://www.math.harvard.edu/~mazur/preprints/when_is_one.pdf .
A great paper, although it deals with monads from a mathematical perspective, not a programming one. There are separate Wikipedia articles on these concepts, and I do not really understand the latter, but I find http://en.wikibooks.org/wiki/Haskell/Category_theory useful in bringing them together. ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
