Functions - TorbScript

A function is a few lines with a name. fn greet(name: String) makes a function called greet that needs one value, a String it calls name. Writing greet "Ada" runs its lines with name standing for "Ada".

Calling a function looks like print, and that is no accident: print is a function too.

fn greet(name: String) {
  print "Hello, {name}!"
}

greet "Ada"
greet "Alan"
// prints Hello, Ada!
// prints Hello, Alan!

A function that answers#

A function can hand a value back. : Int after the parentheses says what kind of value comes back, and the last line of the function is that value. A call that is part of something bigger - like double(21) inside print - keeps its value in parentheses.

fn double(number: Int): Int {
  number * 2
}

print double(21)
print(double(5) + 1)
// prints 42
// prints 11

Exercise#

Write a function square that takes an Int and gives back the number times itself, so the program prints 25.

// Write the function square here

print square(5)

Expected output

Run it on your computer: torb run functions.trb

Hint

Start like double above: fn square(number: Int): Int { ... }, with number * number as its last line.

Solution

fn square(number: Int): Int {
  number * number
}

print square(5)
// prints 25

Recap#

fn name(value: Type) { ... } makes a function, : Type after the parentheses says what it gives back, and its last line is the answer.