Clojure Programming/Examples/Norvig Spelling Corrector

Peter Norvig wrote an excellent example of a spelling corrector in Python. You can see How to Write a Spelling Corrector for a more detailed explanation. This code, translated into Clojure by language creator Rich Hickey, demonstrates the Python-like brevity of Clojure: (defn words [text] (re-seq #"[a-z]+" (.toLowerCase text))) (defn train [features] (reduce (fn [model f] (assoc model f (inc (get model f 0)))) {} features)) (def *nwords* (train (words (slurp "big.txt")))) (defn edits1 [word] (let [alphabet "abcdefghijklmnopqrstuvwxyz", n (count word)] (distinct (concat (for [i (range n)] (str (subs word 0 i) (subs word (inc i)))) (for [i (range (dec n))] (str (subs word 0 i) (nth word (inc i)) (nth word i) (subs word (+ 2 i)))) (for [i (range n) c alphabet] (str (subs word 0 i) c (subs word (inc i)))) (for [i (range (inc n)) c alphabet] (str (subs word 0 i) c (subs word i))))))) (defn known [words nwords] (not-empty (set (for [w words :when (nwords w)] w)))) (defn known-edits2 [word nwords] (not-empty (set (for [e1 (edits1 word) e2 (edits1 e1) :when (nwords e2)] e2)))) (defn correct [word nwords] (let [candidates (or (known [word] nwords) (known (edits1 word) nwords) (known-edits2 word nwords) [word])] (apply max-key #(get nwords % 1) candidates))) To use: (correct "misstake" *nwords*) (correct "speling" *nwords*) Note: training with big.txt may require the jvm to be started with a heap bigger than its default. You can increase the heap size either by starting java with the "-server" option or setting the maximum heap size explicitly: "java -Xmx128m ..."