The earliest memory I have of ‘programming’ is in the early/mid 90s when my father brought home a computer from work. We could play games on it … so of course I took the spreadsheet program he used (LOTUS 123, did I date myself with that?) and tried to modify it to print out a helpful message for him. It … halfway worked? At least I could undo it so he could get back to work…

After that, I picked up programming for real in QBASIC (I still have a few of those programs lying around), got my own (junky) Linux desktop from my cousin, tried to learn VBasic (without a Windows machine), and eventually made it to high school… In college, I studied computer science and mathematics, mostly programming in Java/.NET, although with a bit of everything in the mix. A few of my oldest programming posts on this blog are from that time.

After that, on to grad school! Originally, I was going to study computational linguistics, but that fell through. Then programming languages (the school’s specialty). And finally I ended up studying censorship and computer security… before taking a hard turn into the private sector to follow my PhD advisor.

Since then, I’ve worked in the computer security space at a couple of different companies. Some don’t exist any more, some you’ve probably heard of. I still program for fun too, and not just in security.

But really, I still have a habit of doing a little bit of everything. Whatever seems interesting at the time!

Authorship attribution: Part 2

Last time, we used word rank to try to figure out who could possibly have written Cuckoo’s calling. It didn’t work out so well, but we at least have a nice framework in place. So perhaps we can try a few more ways of turning entire novels into a few numbers.

read more...


Racket Roguelike: Post-mortem

Almost four months ago, I started writing a series on how to write a roguelike in Racket. I believed then as I believe now that Racket is an excellent all around language and that I would like to see more done with it–particularly in games.

read more...


A programming puzzle: f(f(n)) = -n

Two Programming Praxis puzzles in a week? Madness! Let’s do it!

This time, the puzzle at first seems rather minimal:

Write a function f so that f(f(n)) = -n for all integers n.

If you haven’t seen this problem before, take a moment to think though it. It’s a neat little problem–a close cousin to a lateral thinking puzzle.

read more...


Racket Roguelike 9: Daedalus' wrath!

I think by now it’s well past time that we got to adding a bit more content. So far, here’s what we have (bolded entries we actually used in day 8):

  • entities: rat, goblin, bomb, bomber goblin
  • armor: leather, chain, plate, enchanted
  • weapons: club, dagger, battle axe, longsword, magic sword
  • potions: health potion
  • coins: copper, silver, gold, platinum
  • levels: forest, caves

We can do better than that though!

read more...


Swap list nodes

It’s been rather a while since I’ve worked out a Programming Praxis problem, but they posted a new one yesterday, so now seems as good a time as any. The problem is relatively simple:

Given a linked list, swap the kth node from the head of the list with the kth node from the end of the list.

Since all lists in Scheme are linked lists, that part seems easy enough. To make the problem a little more interesting however, I’m going to work it out in a purely functional manner: no mutation.

read more...