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Higher-Order Functions

A higher-order function is a function that takes other functions as arguments or returns them as results. This enables powerful programming techniques, such as callbacks, function composition, and abstraction of common patterns.

Higher-order functions are a key feature of functional programming and allow you to write more flexible and reusable code.

Example: Higher-Order Function

fn apply_twice(f, x) {
    return f(f(x))
}

fn increment(n) {
    return n + 1
}

let result = apply_twice(increment, 3)  # Should return 5

In this example:

  • apply_twice is a higher-order function because it takes another function f as an argument, along with a value x.
  • It applies the function f to x two times in a row. So, if f adds 1, then apply_twice(f, 3) will add 1 twice to 3, giving 5.
  • increment is a simple function that adds 1 to its input.
  • apply_twice(increment, 3) first computes increment(3) (which is 4), then increment(4) (which is 5), so the result is 5.

This shows how you can pass functions as arguments to other functions, which is what makes a function "higher-order."

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