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Lisp Presentations

Posted on 2008-12-01 by Curt Sampson :: comments enabled

The November 27th meeting went very well, with more than a dozen people showing up.

John Fremlin’s presentation was not, as I’d claimed, on his Lisp web server (a presentation he actually gave at a recent TLUG meeting) but was instead called Glimpses of Lisp: Fibonacci and the Netflix Prize, and give some insight into how one does things differently in Lisp over other languages, with some particularly interesting points about compile-time optimization via the macro system. He’s graciously allowed us to host a copy of his slides.

The second presentation was from Jianshi Huang, on Qi. From the web page:

Qi is an award-winning Lisp-based functional programming language that offers the best of Common Lisp with the advantages of pattern matching, l calculus consistency, and optional static type checking. It uses sequent calculus notation to define types, and has the most powerful type system of any existing functional language, including ML and Haskell.

As it turns out, from this overview, Qi offers quite an interesting type system, and is a good contrast to Haskell. One major difference was the ability to switch between dynamic and static type checking, both by turning the type checker on or off and by defining types for only some of the data values. It also, while more verbose than Haskell, appears to offer the potential for some very nice support for dependent types. Perhaps in the upcoming year we can convince Huang to give another presentation focusing on this aspect of the system.

This was certainly one of the more interesting TSAC meetings we’ve had recently.

The next meeting will be on the 18th, moved a week earlier than normal so it doesn’t fall on Christmas Day.

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