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  1. (ns clojurach.core
  2.   (:require [clojure.test :as test :refer [deftest testing is are]]))
  3.  
  4. (defn grep-n [n pred coll]
  5.   (->> coll
  6.        (map-indexed (fn [i x] (clojure.lang.MapEntry. i x)))
  7.        (partition (-> n (* 2) inc) 1)
  8.        (filter #(-> % (nth n) val pred))
  9.        (apply concat)
  10.        distinct
  11.        (map val)))
  12.  
  13. ;; (grep-n 1 #{:b :d} [:a :b :c :d :e :f :g :h])
  14.  
  15. (deftest grep-n-test
  16.   (are [n pred #_=> result]
  17.     (= (grep-n n pred [:a :b :c :d :e :f :g :h])
  18.        result)
  19.  
  20.     1 #{:b}    #_=> [:a :b :c]
  21.     1 #{:b :d} #_=> [:a :b :c :d :e]
  22.     1 #{:b :g} #_=> [:a :b :c :f :g :h]
  23.     3 #{:d}    #_=> [:a :b :c :d :e :f :g]
  24.     2 #{:c :f} #_=> [:a :b :c :d :e :f :g :h]
  25.     ))
  26.  
  27. (test/successful? (test/run-tests))
  28.  
Success #stdin #stdout 1.48s 86136KB
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Standard input is empty
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Testing clojurach.core

Ran 1 tests containing 5 assertions.
0 failures, 0 errors.
https://ideone.com/WWe0HI
language:
Clojure (clojure 1.10.0)
created:
6 years ago
visibility:
public

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