In my day job, I deal with a lot of perl. After really taking the time to learn it, and working with it in a production environment, I really have a new respect for perl. But that’s a topic for another day. The other day, someone presented me with a perl coding challenge, and it took me a while to come up with the answer. Granted, I’m not really a perl guru, so I’m not too concerned, but I wanted to talk about and document how I solved the problem. The challenge can be simplified a little bit, and restated almost like a homework problem:
Given 2 arrays, find the union, intersection and difference.
See, here’s the thing. Most every other high level language makes this pretty trivial. PHP has the built in functions array_intersec and array_diff, in Ruby, you can just do something like ary1 & ary2 or ary1 - ary2, etc… Perl’s arrays suck eggs. I’m serious, arrays in perl are virtually useless… Well, that’s too strong. Array’s in perl are emenintly useful, they’re just kind of dumb. In order to do most serious processing in perl, you wind up turning things into hashes. And that’s basically what you have to do to get the array intersection, difference and union. Here’s a little script that does the job.