Long time readers are probably aware that I don't care for the Common Lisp
loop macro. It's not Lispy and I always have a hard time remembering its syntax. Happily, Chris Bagley, who I've mentioned before, has a video for that.
Bagley begins by recounting the usual arguments against the
loop macro and why he uses it despite those arguments. The meat of the video, though, is a series of examples that demonstrate many of the basic
loop macro constructs. After watching the video you probably won't be a
loop-master but you'll have an idea of how things work and be able to read them in other people's code. This is an excellent video—it's almost enough to make me start using
loop. If you're a Lisper and not sure of how
loop works, give this video 19 minutes of your time.