4clojure.clj

;; The 10 Scala one-liners tranlated to Clojure.
;; http://mkaz.com/solog/scala/10-scala-one-liners-to-impress-your-friends.html

;; Oh, there are more of them:
;; Python: http://codeblog.dhananjaynene.com/2011/06/10-python-one-liners-to-impress-your-friends/
;; Ruby: http://programmingzen.com/2011/06/02/10-ruby-one-liners-to-impress-your-friends/
;; CoffeeScript: http://ricardo.cc/2011/06/02/10-CoffeeScript-One-Liners-to-Impress-Your-Friends.html
;; Another Clojure version: http://freegeek.in/blog/2011/06/10-clojure-one-liners/

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;;; 1. Multiple Each Item in a List by 2

(map #(* 2 %) (range 1 11))

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;;; 2. Sum a List of Numbers

(reduce + (range 1 11))

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;;; 3. Verify if Exists in a String

(let [wl #{"scala" "akka" "play framework" "sbt" "typesafe"}
      tweet "This is an example tweet talking about scala and sbt."]
  ;; Sets are function of their keys
  (some wl (clojure.string/split tweet #"\p{Space}")))

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;;; 4. Read in a File

(let [my-str (slurp "data.txt")
      my-seq (clojure.string/split-lines my-str)]
  ;; Or reading lines lazily, so that the file contents don't need to fit in
  ;; memory...
  (with-open [r (clojure.java.io/reader "data.txt")]
    (doseq [line (line-seq r)]
      (do-stuff-with line))))

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;;; 5. Happy Birthday to You!

(dotimes [i 3]
  (println "Happy Birthday" (if (= i 2) "dear NAME" "to You")))

;; Or a bit more like the Scala solution
(doseq [s (map #(str "Happy Birthday " (if (= 3 %) "dear NAME" "to You"))
               [1 2 3])]
  (println s))

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;;; 6. Filter list of numbers

(let [[fail pass] (split-with #(< % 60) [49 58 76 82 88 90])]
  (println "FAIL:" fail "\nPASS:" pass))

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;;; 7. Fetch and Parse an XML web service

(clojure.xml/parse "http://search.twitter.com/search.atom?&q=scala")

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;;; 8. Find minimum (or maximum) in a List

(let [v [14 35 -7 46 98]]
  {:min (reduce min v)
   :max (reduce max v)})

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;;; 9. Parallel Processing

(let [r (pmap #(process-item %) data-list)]
  (do-stuff-with r))

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;;; 10. Sieve of Eratosthenes

(defn sieve [n]
  (let [r (range 2 (inc n))]
    (reduce (fn [ps x]
              (if (ps x)
                (clojure.set/difference ps (range (* x x) n x))
                ps))
            (set r)
            r)))