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43 lines
1.4 KiB
Clojure
43 lines
1.4 KiB
Clojure
(ns koans.10-runtime-polymorphism
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(:require [koan-engine.core :refer :all]))
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(defn hello
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([] "Hello World!")
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([a] (str "Hello, you silly " a "."))
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([a & more] (str "Hello to this group: "
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(apply str
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(interpose ", " (cons a more)))
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"!")))
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(defmulti diet (fn [x] (:eater x)))
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(defmethod diet :herbivore [a] (str (:name a) " eats veggies."))
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(defmethod diet :carnivore [a] (str (:name a) " eats animals."))
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(defmethod diet :default [a] (str "I don't know what " (:name a) " eats."))
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(meditations
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"Some functions can be used in different ways - with no arguments"
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(= "Hello World!" (hello))
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"With one argument"
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(= "Hello, you silly world." (hello "world"))
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"Or with many arguments"
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(= "Hello to this group: Peter, Paul, Mary!"
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(hello "Peter" "Paul" "Mary"))
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"Multimethods allow more complex dispatching"
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(= "Bambi eats veggies."
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(diet {:species "deer" :name "Bambi" :age 1 :eater :herbivore}))
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"Animals have different names"
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(= "Thumper eats veggies."
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(diet {:species "rabbit" :name "Thumper" :age 1 :eater :herbivore}))
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"Different methods are used depending on the dispatch function result"
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(= "Simba eats animals."
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(diet {:species "lion" :name "Simba" :age 1 :eater :carnivore}))
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"You may use a default method when no others match"
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(= "I don't know what Rich Hickey eats."
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(diet {:name "Rich Hickey"})))
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