38 lines
955 B
Clojure
38 lines
955 B
Clojure
(ns koans.07-functions
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(:require [koan-engine.core :refer :all]))
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(defn multiply-by-ten [n]
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(* 10 n))
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(defn square [n] (* n n))
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(meditations
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"Calling a function is like giving it a hug with parentheses"
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(= 81 (square 9))
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"Functions are usually defined before they are used"
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(= 20 (multiply-by-ten 2))
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"But they can also be defined inline"
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(= 10 ((fn [n] (* 5 n)) 2))
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"Or using an even shorter syntax"
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(= 60 (#(* 15 %) 4))
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"Even anonymous functions may take multiple arguments"
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(= 15 (#(+ %1 %2 %3) 4 5 6))
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"Arguments can also be skipped"
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(= "AACC" (#(str "AA" %2) "bb" "CC"))
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"One function can beget another"
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(= 9 (((fn [] +)) 4 5))
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"Functions can also take other functions as input"
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(= 20 ((fn [f] (f 4 5)) *))
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"Higher-order functions take function arguments"
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(= 25 ((fn [f] (f 5)) (fn [n] (* n n))))
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"But they are often better written using the names of functions"
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(= 25 ((fn [f] (f 5)) square)))
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