Summary - Functions

Combine arrow, named and first-class to write a math helper.

Summary - Functions

This group covered the building blocks of functions. void marks no return; int, String and friends mark a returned value. return sends the value and ends the function.

The arrow => shortens single-line returns. Named and positional parameters build flexible signatures; required is mandatory, defaults guard against missing calls.

Being first-class, functions travel as values; you apply callbacks and higher-order patterns. The final task blends all of this into a small math helper.

Exercise Triple compute

Define a triple(int n) arrow function whose body is n * 3. Add a print(triple(7)) call inside main.

Show example solution

int triple(int n) => n * 3;

void main() {
  print(triple(7));
}

Exercise Math helper

Define a doubleIt(int n) arrow function (n * 2). Define an apply(int Function(int) f, int x) higher-order function (print(f(x))). Add an apply(doubleIt, 6) call inside main.

Show example solution

int doubleIt(int n) => n * 2;

void apply(int Function(int) f, int x) {
  print(f(x));
}

void main() {
  apply(doubleIt, 6);
}

Test yourself

Which is an arrow function?
- int f(int n) { return n; }
- int f(int n) { n; }
- void f(int n) => return n;
- int f(int n) => n;
Show answer

int f(int n) => n; — the => marks an arrow function.
Match the concepts

void

No return
=>

Arrow function
required

Mandatory named
Function(int)

Function type

Named call

void greet({required String name}) { print(name); }
void main() { greet(____); }

Show answer

void greet({required String name}) { print(name); }
void main() { greet(name: 'Ayşe'); }

Next lesson: Nullable types

We Are Enhancing Your Experience

Cookie Preferences

Strictly Necessary Cookies

Analytical Cookies