Essay

If I’m not pure, at least my functions are

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It is often suggested that the programming language should support specifying that a routine is pure; many people have indeed proposed the addition of a keyword such as pure to Eiffel. One of the reasons this is not — in my opinion — such a great idea is that purity is just a special case of the more general problem of framing: specifying and verifying what a routine does not change. If we can specify an arbitrary frame property, then we can, as a special case covered by the general mechanism, specify that a routine changes nothing. The language solution is simple: no routine may change the value of a query other than those specified in its postcondition




Assessing concurrency models

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In a recent experiment with students we wanted to know how the SCOOP concurrency model compares to Java Threads in terms of ease of learning, program readability and correctness. Our group, however, is heavily involved with SCOOP. How did we address the risk of bias, and other parts of the “Professor Smith Syndrome”? What are our results, and can you believe them?







The rise of empirical software engineering (II): what we are still missing

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p>  (This article was initially published in the CACM blog.) The previous post under  the heading of empirical software engineering hailed the remarkable recent progress of this field, made possible in particular by the availability of large-scale open-source repositories and by the opening up of some commercial code bases. Has the empirical side of software … Read more




One cheer for incremental research

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[Note: an updated version of this article (June 2011) appears in the Communications of the ACM blog.] The world of research funding, always a little strange, has of late been prey to a new craze: paradigm-shift mania. We will only fund twenty curly-haired cranky-sounding visionaries in the hope that one of them will invent relativity. The rest of … Read more




The good and the ugly

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Once in a while one hits a tool that is just right. An example worth publicizing is the EasyChair system for conference management [1], which  — after a first experience as reviewer —  I have selected whenever I was in a position to make the choice for a new conference in recent years. At first … Read more




Computer technology: making mozzies out of betties

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Are you a Beethoven or a Mozart? If you’ll pardon the familarity, are you more of a betty or more of a mozzy? I am a betty. I am not referring to my musical abilities but to my writing style; actually, not the style of my writings (I haven’t completed any choral fantasies yet) but … Read more