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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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On Arc

From Paul Graham's Arc release annoucement:

Over the years my appreciation for lists has increased. In exploratory programming, the fact that it's unclear what a list represents is an advantage, because you yourself are unclear about what type of program you're trying to write. The most important thing is not to constrain the evolution of your ideas. So the less you commit yourself in writing to what your data structures represent, the better.

Clearly Paul has been living in a cave for the past thirty-five years and did not hear about those quaint ideas, abstract data types and representation independence.

He seems to miss the obvious that using a list to represent a point is quite constraining because you are forced to require one coordinate be the first element of the list and the other coordinate be the second element of the list, and if you ever want to change it, good luck. I suppose his rebuttal would be »oh, it just takes too long or too many tokens to define an ADT for points«.

I really wonder how long it is going to take people to truly learn that telling the compiler about the structure of the data you work with is just as important as telling it about the control flow.

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