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29 lines
770 B
Clojure
29 lines
770 B
Clojure
(ns koans.11-lazy-sequences
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(:require [koan-engine.core :refer :all]))
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(meditations
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"There are many ways to generate a sequence"
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(= '(1 2 3 4) (range 1 5))
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"The range starts at the beginning by default"
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(= '(0 1 2 3 4) (range 5))
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"Only take what you need when the sequence is large"
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(= [0 1 2 3 4 5 6 7 8 9]
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(take 10 (range 100)))
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"Or limit results by dropping what you don't need"
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(= [95 96 97 98 99]
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(drop 95 (range 100)))
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"Iteration provides an infinite lazy sequence"
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(= '(1 2 4 8 16 32 64 128) (take 8 (iterate (fn [x] (* x 2)) 1)))
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"Repetition is key"
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(= [:a :a :a :a :a :a :a :a :a :a]
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(repeat 10 :a))
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"Iteration can be used for repetition"
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(= (repeat 100 "hello")
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(take 100 (iterate #(str %) "hello"))))
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