Loops

A loop is the programming term for running the same chunk of code over and over.

In 99% of these case, you’ll be using a foreach loop.

Foreach Loops 

A foreach loop runs the same block of code for every item in a List.

foreach $list as $item {
    // $item = the value of the current cycle of the loop
}

Example:

$colors = ['Red', 'Blue', 'Yellow']

foreach $colors as $color {
    print($color ~ ' is a primary color.')
}

//= 'Red is a primary color'
//= 'Blue is a primary color'
//= 'Yellow is a primary color'

Looping Over a Range 

Use the range function to loop over a range of numbers.

foreach range(1, 3) as $n {
    print($n)
}

//= 1
//= 2
//= 3

You can give a step as the third parameter, to make the loop increment by that value.

// step = 2
foreach range(1, 10, 2) as $n {
    print($n)
}

//= 2
//= 4
//= 6
//= 8
//= 10

Looping Over Keys 

You can also loop over the key/value pairs of a Map.

Use a slash / to define separate variables for the current key and value.

foreach $map as $key/$value {
    ...
}

Example:

$countryCodes = {
    MX: 'Mexico'
    FI: 'Finland'
    JP: 'Japan'
}

foreach $countryCodes as $code/$name {
    print($code ~ ' is the code for ' ~ $name)
}

//= MX is the code for Mexico
//= FI is the code for Finland
//= JP is the code for Japan

List Indexes

You can also use this approach to loop over List indexes.

$letters = ['A', 'B', 'C']

foreach $letters as $i/$letter {
    print($i ~ ' --> ' ~ $letter)
}

//= 1 --> A
//= 2 --> B
//= 3 --> C

Loop Control 

break Statement

Use break to immediately exit a loop.

The program will jump to the end of the block and continue from there.

$lines = File.read('quotes.txt')

// Find the 1st quote that refers to 'inspiration'
foreach $lines as $line {
    if $line.contains('inspiration') {
        print($line)
        break  // end the loop
    }
}

continue Statement

Use continue to skip the current cycle of a loop.

It will immediately jump to the top of the block and resume the next cycle.

$lines = File.read('quotes.txt')

// Print all lines, but skip any that refer
// to 'laziness'
foreach $lines as $line {
    if $line.contains('laziness') {
        continue  // skip to the next cycle
    }
    print($line)
}

Infinite Loops 

The loop statement will keep repeating until you exit via break.

This is useful when you don’t know exactly how many times it should repeat.

loop {
    $quote = getNextQuote()

    if !$quote {
        break
    }
    else if $quote.contains('creativity') {
        print($quote)
    }
}