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(def naturals (drop 1 (range)))

(def fizz-buzz-seq
  (map #(clojure.string/replace (str %1 %2) #"^$" (str %3))
       (cycle '("" "" "Fizz"))
       (cycle '("" "" "" "" "Buzz"))
       naturals))

(defn fizz-buzz [n]
  (clojure.string/join " " (take n fizz-buzz-seq)))

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;;
;; Destructuring
;;

;; Destructuring is a concise syntax for declaratively pulling apart collections and
;; binding values contained therein as named locals within a let form.
;; (Clojure Programming, Chas Emerick, Brian Carper, Christophe Grand)

;; Since it's a facility provided by let, it can be used
;; in any expression that implicitly uses let (like fn, defn, loop, etc).

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(def test-address
  {:street-address "123 Test Lane"
   :city "Testerville"
   :state "TX"})

;"Destructuring is an arbiter: it breaks up arguments"
(= "__" ((fn [[a b]] (str b a))
       [:foo :bar]))

;"Whether in function definitions"

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Reverse Polish Notation calculator kata

Useful info:

Reverse Polish Notation algorithm explanation

Online Reverse Polish Notation Calculator to check your results.

Examples:

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;;--------------
;;
;; A bit about Clojure functions
;;
;;--------------

;; Functions are first class values in Clojure.

;;--------------
;; 1. fn form

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(defn- happy? [n visited]
  (if (contains? visited n)
    false
    (if (= n 1)
      true
      (let [ndigits (decompose-in-digits n)
            sum-of-squares (apply + (map square ndigits))]
        (recur sum-of-squares (conj visited n))))))

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Password Validator kata

• A password should have more than 6 chars

• A password should contain at least 1 char in upper case

• A password should contain at least 1 char in lower case

• A password should contain at least 1 underscore

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"_Ab3ccc" -> ok

"c" -> wrong

"_b3c" -> wrong

"_Ab3cc" -> wrong

"_Abcccc" -> wrong

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Rationals addition kata

We'll program the addition of two rationals using TDD.

Suggested API for the method (in Java):

  public Rational add(Rational rational);

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(ns password-validator.core)

(defn- has-more-than-6-chars? [password]
  (> (count password) 6))

(defn- any? [pred coll]
  (not= nil (some pred coll)))

(def ^:private contains-at-least-one-upper-case-char?
  (partial any? #(Character/isUpperCase %)))