Loops

Boa supports two kinds of loops: the for loop and the while loop.

The for loop

Boa does not have a C-style for (initialisation; condition; incrementation) but a for loop based on ranges:

for number in [1, 2, 3, 4, 5]:
    println(number)

// will print:
// 1
// 2
// 3
// 4
// 5

Use break to leave the loop as soon as it is encountered, and continue to directly jump to the next iteration.

It is possible to combine multiple ranges to write nested for loops in a more concise way:

for
    number in [1, 2, 3]
    boolean in [true, false]
    character in ['a', 'b', 'c', 'd']
:
    ...

// ^ this is equivalent to:

for number in [1, 2, 3]:
    for boolean in [true, false]:
        for character in ['a', 'b', 'c', 'd']:
            ...

Conditionals (called guards in that case) can be added to the for expression to filter the iterated values:

for number in [0, 1, 2, 3] if number % 2 == 0:
    println(number)

// will print
// 0
// 2

for
    number in [1, 2, 3]
    boolean in [true, false]
    character in ['a', 'b', 'c']
    if number % 2 != 0
    if character == 'b' || character == 'c' // another if acts as an "and"
:
    println(f"{number}, {boolean}, {character}")

// will print
// 1, true, b
// 1, false, b
// 1, true, c
// 1, false, c
// 3, true, b
// 3, false, b
// 3, true, c
// 3, false, c

Note that the first guard can be written only after the last range of the for expression. For instance, the following example is invalid:

for
    number in [0, 1, 2, 3]
    if number % 2 == 0
    boolean in [true, false]
:
    ...

The while loop

The while loop in Boa is similar to basically all the other existing while loops:

while condition:
    ...

Use true as the condition to create an infinite loop:

while true:
    ...

Like the for loop, it is possible to use break and continue inside a while loop.