Functional Programming explained to my grandma

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Dummy example of lambda

Until now we have used a lot of functions. We specified that we want them to be pure (no side effect). We have seen that we can pass it as a parameter to other functions or use it in a return. Also, we have seen that by currying we can define precise functions that improve readability and reuse.

However, you will run into a function has no reason to be reused. In this case, we want to use it anonymously. This is what we call a lambda expression.

In this example, the operation function takes a function as a parameter and will apply it to each number from 1 to x, where x is the high limit parameter.

Let's try to use it to define three different functions:

sum : a function to add each number from 1 to x
sumSquare: a function to add each squared number from 1 to x
sumPeer: a function to add the x first odd numbers

To complete these, let's use lambdas as the parameter of "operation"

Implement different sums

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package example
/**
  * Created by charlotte on 13/05/17.
  */
object Lamdba {
  /**
    * will apply the f function to the a first integers
    * @param a high limit
    * @param f a function to apply
    * @return the sum of the a first number where the f function has been applied
    */
  def operation(a:Int)(f:(Int)=> Int): Int={
    def opeAcc(acc : Int, lim: Int): Int={
      if(lim == 0) acc
      else opeAcc(acc + f(lim), lim -1)
    }
    opeAcc(0, a)
  }
  /**
    * a function that will return the sum from 1 to a
    */
  def sum(a : Int): Int = ???
  /**

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Dummy example of lambda

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