43 lines
1.1 KiB
Clojure
43 lines
1.1 KiB
Clojure
(ns koans.15-refs
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(:require [koan-engine.core :refer :all]))
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(def the-world (ref "hello"))
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(def bizarro-world (ref {}))
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(meditations
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"In the beginning, there was a word"
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(= __ (deref the-world))
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"You can get the word more succinctly, but it's the same"
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(= __ @the-world)
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"You can be the change you wish to see in the world."
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(= __ (do
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(dosync (ref-set the-world "better"))
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@the-world))
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"Alter where you need not replace"
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(= __ (let [exclamator (fn [x] (str x "!"))]
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(dosync
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(alter the-world exclamator)
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(alter the-world exclamator)
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(alter the-world exclamator))
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@the-world))
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"Don't forget to do your work in a transaction!"
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(= 0 (do __
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@the-world))
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"Functions passed to alter may depend on the data in the ref"
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(= 20 (do
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(dosync (alter the-world ___))))
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"Two worlds are better than one"
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(= ["Real Jerry" "Bizarro Jerry"]
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(do
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(dosync
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(ref-set the-world {})
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(alter the-world assoc :jerry "Real Jerry")
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(alter bizarro-world assoc :jerry "Bizarro Jerry")
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__))))
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