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LESSON 4.8

Functions That Take Functions

A function can receive another function as a parameter. The type Fn(Int32) => Int32 means it takes an Int32 and returns an Int32 .

Goal Update apply_twice so it applies its function two times. The triple lambda with 2 should produce 18, inc with 5 should produce 7, and the square lambda with 3 should produce 81.

Write a Zirk program, then run it to see the world react.

Your code

main.zirk

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Zirk

import { stdout } from std.io;

fn apply_twice(f: Fn(Int32) => Int32, x: Int32): Int32 {
    return f(x);
}

fn inc(n: Int32): Int32 {
    return n + 1;
}

fn main(): Void {
    inmut triple = (n: Int32): Int32 => n * 3;
    stdout.println(apply_twice(triple, 2));
    stdout.println(apply_twice(inc, 5));
    stdout.println(apply_twice((n: Int32): Int32 => n * n, 3));
}

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Output

Your program output will appear here.

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