Functions04FirstClassCitizen.sc

package day01session03.functions.solution

/*
 * This file is part of the "Scala Hack Session".
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 * Scala Hack Session is distributed in the hope that it will be useful,
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 *
 * You should have received a copy of the GNU General Public License
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 * =================================================================================
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 */
object Functions04FirstClassCitizen {
  def increase(x: Int) = x + 1                    //> increase: (x: Int)Int
  //Functions are first-class citizens
  //Since functions are treated as values, we can pass it to other functions
  //This function calls the the function param on both a and b before adding both values together
  def increaseBeforeAdd(a: Int, b: Int, operator: Int => Int) = operator(a) + operator(b)
                                                  //> increaseBeforeAdd: (a: Int, b: Int, operator: Int => Int)Int
  //Now call and pass the required params including the increase function
  increaseBeforeAdd(2, 3, increase)               //> res0: Int = 7
  //Here is another general definition allowing to pass any kind of function
  def logOperation(f: => Any) = println(s"Operation: $f")
                                                  //> logOperation: (f: => Any)Unit
  //Log increase
  logOperation(increase(2))                       //> Operation: 3
  //Log increaseBeforeAdd
  logOperation(increaseBeforeAdd(2, 3, increase)) //> Operation: 7
  //Log a string using String or StringUtils
  logOperation("Hello, Scala")                    //> Operation: Hello, Scala
  logOperation(s"increase(2) = ${increase(2)}")   //> Operation: increase(2) = 3
}