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1 (ns rlm.clojure-example)
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2
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3 (defn curry
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4 "takes a function with a fixed number of args and modifies
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5 it to that it will be automaticaly curried when called with
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6 less args"
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7 ([num-args f & eval-list]
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8 (if (= num-args (count eval-list))
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9 (apply f eval-list)
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10 (fn [& args]
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11 (apply curry num-args f (concat eval-list args))))))
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12
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13 (defn mix
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14 "Takes any number of mathematically equal functions with
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15 possibly different run-times and returns a function that
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16 runs each in a separate thread, returns the result from
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17 the first thread which finishes, and cancels the other threads."
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18 {:author "Robert McIntyre"}
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19 ([& functions]
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20 (fn [& args]
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21 (let [result (promise)
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22 futures
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23 (doall (for [fun functions]
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24 (future (deliver result (apply fun args)))))
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25 answer @result]
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26 (dorun (map future-cancel futures))
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27 answer))))
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28
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29 (defn memoize*
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30 "Returns a memoized version of a referentially transparent
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31 function. The memoized version of the function keeps a cache of the
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32 mapping from argument to results and, when calls with the same
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33 arguments are repeated often, has higher performance at the expense
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34 of higher memory use."
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35 {:added "1.0"}
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36 [f]
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37 (let [mem (atom {})]
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38 (fn [& args]
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39 (if-let [e (find @mem args)]
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40 (val e)
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41 (let [ret (apply f args)]
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42 (swap! mem assoc args ret)
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43 ret)))))
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44
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45 ;;immutable data structures
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46 (def r {:a :a :b :b})
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47 (def b (assoc r :c :c))
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48
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49 (defn collapse [coll & head]
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50 (if (= (count coll) 0)
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51 (first head)
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52 (let [x (first coll)]
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53 (if (list? x)
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54 (collapse (concat x (rest coll)) (first head))
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55 (collapse (rest coll) (conj (vec (first head)) x))))))
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56 ;;email clojure group about this
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57
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58
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59 (defn collapse* [coll]
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60 (loop [head [] body coll]
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61 (let [x (first body)]
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62 (cond (= (count body) 0) head
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63 (list? x) (recur head (concat x (next body)))
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64 true (recur (conj head x) (next body))))))
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65
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66
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67
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68
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69
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