Lists - TorbScript

A list holds several values in a row, between square brackets. The values are numbered from 0, so fruits[0] is the first one. fruits.length() says how many there are, and a for loop goes through them one after the other.

const fruits = ["apple", "banana", "cherry"]
print fruits[0]
print fruits.length()
for fruit in fruits {
  print "I like {fruit}."
}
// prints apple
// prints 3
// prints I like apple.
// prints I like banana.
// prints I like cherry.

Adding to a list#

append adds a value at the end. It changes the list, so the list needs a var, just like a number you change.

var shopping = ["bread"]
shopping.append "milk"
shopping.append "eggs"
print shopping
// prints ["bread", "milk", "eggs"]

Two names, two lists#

When you give a list a second name, you get a copy. Changing the copy leaves the first list alone, so nothing changes behind your back: a value only changes where you change it.

Many languages share one list between both names instead, and a change through one name shows up under the other. TorbScript does not: every value behaves like a number here. The reference calls this value semantics.

const original = ["bread"]
var copy = original
copy.append "milk"
print original
print copy
// prints ["bread"]
// prints ["bread", "milk"]

Exercise#

Add up the prices with a for loop, so the program prints Total: 16.

const prices = [3, 8, 5]
var total = 0
print "Total: {total}"

Expected output

Total: 16

Run it on your computer: torb run lists.trb

Hint

Go through the list with for price in prices { ... } and add each price to total.

Solution

const prices = [3, 8, 5]
var total = 0
for price in prices {
  total = total + price
}
print "Total: {total}"
// prints Total: 16

Recap#

A list keeps values in order from position 0, append adds to a var list, and a second name is a copy of its own.