Question

Write a Haskell function for each of the following. In your code, you need to specify the input and output type of each function.

(a) Write a Haskell function bar which takes two integers x and y as input parameters and returns the sum of all positive even integers (z)s' cubes whereas z is bigger than x and smaller than y. You need to use foldl to do the above computation. As an example, if x is 3 and y is 15, then bar will compute (4² +63 +...+14%). Writing README carries 1 points

Answer 1

The Haskell function `bar` takes integers x and y, using `foldl` to calculate the sum of cubes for positive even integers z between x and y (exclusive). The example with x=3 and y=15 computes the sum of cubes for even numbers from 4 to 14.

Below is the Haskell code for the function `bar` as described:

bar :: Integer -> Integer -> Integer

bar x y = foldl (\acc z -> acc + z^3) 0 (filter even [z | z <- [x+1..y-1]])

-- Example usage:

-- let result = bar 3 15

-- putStrLn $ "Result: " ++ show result

Explanation has been given below.

- The function `bar` takes two integers `x` and `y` as input parameters.

- It uses `filter even` to generate a list of even numbers between `x` and `y` (exclusive).

- `foldl (\acc z -> acc + z^3) 0` is used to compute the sum of cubes of the even numbers in the generated list, starting with an initial accumulator value of 0.

The example usage shows how to call the function with `bar 3 15` and print the result.