What is functional programming?

In the early days of my interest in Computer Science (in the late 1980's), flushed with enthusiasm for the connections between Category Theory and Computer Science, I wrote a paper with that title. It was accepted for the first volume of a new journal, Mathematical Structures in Computer Science, and was promised even in the advertisements for the new journal. But then the editors had a change of heart and withdrew their acceptance. (I must find in my papers the letters.)
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Lisp and stack overflow

This semester I am teaching a course which over the years has had many names (Computational algebra, Symbolic computation, Categories and automata, etc, etc) but which is really my thoughts about relations between algebra and computer science. For some years I used Maple as an illustrative programming language, but it is expensive, and the faculty in Como has withdrawn support, closing the laboratory which had Maple installed a couple of years ago. So this year at the last moment I thought of using Common Lisp (Clisp). To be honest I am not a programmer though I have written programs in a large number of different languages but not in Lisp.
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Banditismo e prepotenza

The parish journal of the village where I live has, in addition to the usual announcements of baptisms and communions, a section written by some local historians called "Banditismo e prepotenza" on the banks of the Adda. It has stories about arguments and murders in the 16th century and the efforts of Carlo Borromeo to create order. There is a statue of San Carlo in the centre of the village which last Christmas was adorned with a Santa Claus hat.
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