Higher-order functions are functions that take other functions as arguments or return functions as their results.
One of the great advantages of using higher order functions when we can is composition.
Sorry, but higher order functions and your example(I mean your example with grades, not first part with map) aren't linked at all. None of the functions from your example takes other functions as arguments or returns function as a result.
Of course, you use functions inside other functions and you pass results of other functions as arguments to other functions, but it is not a higher order function if we look at your definition above.
Sorry, but higher order functions and your example(I mean your example with grades, not first part with map) aren't linked at all. None of the functions from your example takes other functions as arguments or returns function as a result.
Of course, you use functions inside other functions and you pass results of other functions as arguments to other functions, but it is not a higher order function if we look at your definition above.
Good catch.