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Control Flow

If Expressions

Conditional execution.

if (condition) {
    // ...
} else if (other_condition) {
    // ...
} else {
    // ...
}

Example:

x: Integer = 10;
if (x > 5) {
    println("Large");
} else {
    println("Small");
}

Loops

While Loop

Executes as long as the condition is true.

mut i: Integer = 0;
while (i < 5) {
    println("{i}");
    i = i + 1;
}

For Loop

Iterates over a range or collection.

Range iteration:

// 'in 5' creates a range from 0 to 4
for (i in 5) {
    println("Iteration {i}");
}

for (i: Float in 5) {
    println("Iteration {i}");
}

end: Integer = 5;
for (i in end) {
    println("Iteration {i}");
}

// Using Range<T> explicitly
r: Range<Integer> = range(1, 10, 2);  // 1, 3, 5, 7, 9
while (r.has_next()) {
    val: Integer = r.next();
    println(to_string(val));
}

for (i: Float in 5) widens each loop binding to Float, but the iterable itself still keeps its original type. For example, Range<Integer> does not implicitly become Range<Float>.

See Range Types for more details on ranges.

Collection iteration:

numbers: List<Integer> = List<Integer>();
// ... add items ...
for (n in numbers) {
    println("{n}");
}

view: &List<Integer> = &numbers;
for (n in view) {
    println("{n}");
}

text: String = "Ahoj";
for (ch in text) {
    println("{ch}");
}

view: &String = &text;
for (ch in view) {
    println("{ch}");
}

Pattern Matching

The match statement is a powerful control flow operator.

val: Integer = 2;
match (val) {
    1 => { println("One"); }
    2 => { println("Two"); }
    _ => { println("Other"); }
}

It is exhaustive, meaning all cases must be covered (using _ as a catch-all if needed).

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