Quiz: CBV or CBN?

In this lesson, we will take quick quiz to better understand CBV and CBN.

While Scala’s default evaluation strategy is call-by-value, call-by-name can be enforced using =>. Hence, it is important to know when to use CBV and when to use CBN. Take a look at the function below.

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def evaluate(x: Int, y: Int) ={
  x * x
}

This function is just like our square function with an added extra parameter y. Now, y isn’t required for the evaluation of the function’s body. Can you figure out which evaluation strategy is faster in the following function calls to the evaluate function?

By faster, we simply mean taking a lesser number of steps to reach the final result.

1

evaluate(2,3)

A)

CBV

B)

CBN

C)

same

Question 1 of 30 attempted

If we wanted the evaluate function to evaluate its first parameter using CBN, the function would be written as below.

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def evaluate(x: => Int, y: Int) ={
  x * x
}
// Driver Code
print(evaluate(7, 2*4))

In the next lesson, we will go over which evaluation strategy should be used depending on the expression to be evaluated.