A short note about a task I am doing at my day job, involving making sure that different caches are cleared consistently. For people wondering about real-life use cases of metaprogramming techniques.

Some musings about my personal history with inheritance and interfaces, solicited by the release of the Go language this week.

This is the updated translation of a beginner-level paper I wrote for Stacktrace one year ago (see http://stacktrace.it/articoli/2008/05/gestione-dei-record-python-1/). It basically discusses Python 2.6 namedtuples (plus some musing of mine).

A quick recipe for readers of digital comics

This summer I have been quite silent on Artima. Here is an update of what I have done and what I plan to do in the future.

What does it mean that two identifiers are equal in a lexically scoped language with hygienic macros? This last episode of part V tries to answer the question, by discussing three different concepts of identifier equality.

In this episode I explain how to break hygiene in Scheme macros by using datum->syntax. I discuss how you can play with the lexical context. Finally, I spend some word on non-hygienic macro systems versus hygienic systems.

If there is a topic which is likely to engender a flame war between Schemers and Lispers, that topic is hygienic macros. It is the time to face it, and to explain what people mean when they allude to the "hygiene problem".

In the last dozen episodes I have defined plenty of macros, but I have not really explained what macros are and how they work. This episode closes the gap: it explains the true meaning of Scheme macros by introducing the concepts of syntax object and of transformer over syntax objects.

In this episode I add another item to the macro programmer toolkit (macros taking macros as arguments) and I bring an argument in favor of good old parentheses.

After a short introduction about the relevance of macros as tools to design abstractions, including full programming languages, I show some common patterns of Scheme macrology: recursive macros, accumulators, and the usage of literals to incorporate helpers in macros.

Observations about the organization of the conference and about the talks discussing the future of Common Lisp.

Some thoughts about programming-language communities, inspired by the Lisp conference I attended last week.

A pointer to the slides I prepared for the Second European Lisp Symposium http://www.european-lisp-symposium.org/

In the last episode we saw that PLT Scheme performs much more instantiation and visiting of modules than other implementations. The reason for such behaviour is that PLT Scheme aims to avoid cross-phase side effects. In this episode I explain what cross-phase side effects are and why they are evil.