A new species

I spent some time last night looking more closely at Carette and Uszkey's new paper on species, as mentioned recently on Lambda the Ultimate. I mostly concentrated on the first few sections and the Haskell bit at the end. They say many tantalizing things, and I had kind of hoped the punchline would be something like "here is how you can write code in a beautifully functional style over graphs and cyclic structures" (assuming I understood the potential of species correctly).  Perhaps in a follow up paper.

I also found it interesting that their dot product operator sounds more like the traditional Cartesian product type (one of each type), and their Cartesian product type sounds much more like an intersection type (the value is a structure having both types). Perhaps it is a notational holdover from previous work on species. It also seem to make for some nice concrete examples of the "locative" aspects of Girard's Ludics.

Now back to reviewing journal and ICFP papers...

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Focusing and higher-order abstract syntax

I figured I would take a few minutes to point out that Noam Zeilberger had an excellent paper in POPL this year on Focusing and higher-order abstract syntax. I've spent some time in the past trying to better understand Andreoli's material on focusing and Girard's* Ludics from the judgmental perspective that I became accustomed to in my formative years, but I never really came up with anything. I found Noam's computational interpertation of focusing quite pleasing.

One low tech solution that has really been helping my wrists lately is that I obtained adjustable height desk for my office. The desks that came with my office were definitely far too tall for me (even when my chair at its maximum height).

* Girard seems to have redecorated his website since I last visited.

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