Inside 206-105

Existential Pontification and Generalized Abstract Digressions

October, 2010

Blog name changed…

...because I don’t live in a room numbered 245s anymore. Yep. :-) This is a cow. They munch grass next to the River Cam. Pop quiz. What do matrix-chain multiplication, longest common subsequence, construction of optimal binary search trees, bitonic euclidean traveling-salesman, edit distance and the Viterbi algorithm have in common?

  • October 27, 2010

OCaml for Haskellers

I’ve started formally learning OCaml (I’ve been reading ML since Okasaki, but I’ve never written any of it), and here are some notes about differences from Haskell from Jason Hickey's Introduction to Objective Caml. The two most notable differences are that OCaml is impure and strict. Features. Here are some features OCaml has that Haskell […]

  • October 25, 2010

Don’t Repeat Yourself is context dependent

I am a member of a group called the Assassins’ Guild. No, we don’t kill people, and no, we don’t play the game Assassin. Instead, we write and run competitive live action role-playing games: you get some game rules describing the universe, a character sheet with goals, abilities and limitations, and we set you loose […]

  • October 22, 2010

Purpose of proof: semi-formal methods

In which the author muses that “semi-formal methods” (that is, non computer-assisted proof writing) should take a more active role in allowing software engineers to communicate with one another. C++0x has a lot of new, whiz-bang features in it, one of which is the atomic operations library. This library has advanced features that enable compiler […]

  • October 20, 2010

Rapidly prototyping scripts in Haskell

I’ve been having some vicious fun over the weekend hacking up a little tool called MMR Hammer in Haskell. I won’t bore you with the vagaries of multimaster replication with Fedora Directory Server; instead, I want to talk about rapidly prototyping scripts in Haskell—programs that are characterized by a low amount of computation and a […]

  • October 18, 2010

Existential type-curry

This post is for those of you have always wondered why we have a forall keyword in Haskell but no exists keyword. Most of the existing tutorials on the web take a very operational viewpoint to what an existential type is, and show that placing the forall in the “right place” results in the correct behavior. […]

  • October 15, 2010

Quote Day

Unattributed to protect the innocent. (But you can probably guess.) “And so these poor programmers, they had to drink this much whiskey to get the job done.” [triumphantly produces a bottle of whiskey and places it on the table.] “And this group of programmers did X, and how hard was that? Two bottles of whiskey.” […]

  • October 13, 2010

Why being a sysadmin will help you do Science!

A complaint I once heard about SIPB is that it leans too much towards the system administration side: we proudly display the services we have deployed and neglect to talk very much about actually programming or conducting novel computer science research (despite the fact that we are very much programmers and some of us are […]

  • October 11, 2010

The HTML purification manifesto

I recently sent Greg Weber an email about his xss-sanitize package, cautioning about his reuse of the pandoc sanitization algorithm for his own package. He responded (with good justification) that a mere caution was not very constructive! So here is my response, the “HTML purification manifesto,” which HTML Purifier follows and which I think is […]

  • October 8, 2010