Translation of the first part of Norvig's solution to xkcd 1313 to clojure

regex-golf.clj

(use '[clojure.string :only [split, join]])
(use '[clojure.set :only [difference]])

(def winners
  (let [w "washington adams jefferson jefferson madison madison monroe 
monroe adams jackson jackson vanburen harrison polk taylor pierce buchanan 
lincoln lincoln grant grant hayes garfield cleveland harrison cleveland mckinley
 mckinley roosevelt taft wilson wilson harding coolidge hoover roosevelt 
roosevelt roosevelt roosevelt truman eisenhower eisenhower kennedy johnson nixon 
nixon carter reagan reagan bush clinton clinton bush bush obama obama"]
    (set (remove empty? (split w #"\s")))))

(def losers
  (let [l "clinton jefferson adams pinckney pinckney clinton king adams 
jackson adams clay vanburen vanburen clay cass scott fremont breckinridge 
mcclellan seymour greeley tilden hancock blaine cleveland harrison bryan bryan 
parker bryan roosevelt hughes cox davis smith hoover landon wilkie dewey dewey 
stevenson stevenson nixon goldwater humphrey mcgovern ford carter mondale 
dukakis bush dole gore kerry mccain romney"]
    (difference (set (remove empty? (split l #"\s"))) winners)))

(defn verify
  "Verify that regex matches all winners but no losers."
  [regex winners losers]
  (let [missed-winners (remove empty? (for [name winners] (when-not (re-find regex name) name)))
        missed-losers  (remove empty? (for [name losers]  (when     (re-find regex name) name)))]
    (when-not (empty? missed-winners) (prn (str "Error: Should match but did not: " (join ", " missed-winners))))
    (when-not (empty? missed-losers)  (prn (str "Error: Should not match but did: " (join ", " missed-losers))))
    (and (empty? missed-winners) (empty? missed-losers))))

(verify #"bu|[rn]t|[coy]e|[mtg]a|j|iso|n[hl]|[ae]d|lev|sh|[lnd]i|[po]o|ls" winners losers)
;;;=> "Error: Should not match but did: fremont"

Hi -
Cool. I found this searching for xkcd and clojure. I have a clojure version too, though it uses simulated annealing instead of Peter's algorithm. You may be one of the few people in the universe who might care. Here's the code and
a blog post. It "wins" by 2 strokes, at a ridiculous cost in cpu.
A while back, I tried "improving" PN's spell-checking using some primitive classification. That was even less successful, though it was slightly better at correcting misspellings of "ein" in German texts.