I have been going through 4Clojure problems. My short-term goal is to rank in the top 100; I just made it to 197 today. I had been reading a bit about Lisp and find the style meshes well with my own thinking (e.g. in PHP, I have a tendency to use foreach loops a lot).

Various solutions (spoilers!):

• https://gist.github.com/1472063 (I keep forgetting sort-by exists)
• https://gist.github.com/1436347 (Juxtapose)
• https://gist.github.com/1434456 (Composition, somewhat awkward, see Twitter)
• https://gist.github.com/1423857 (Reverse interleave)