Ranges

Ranges describe integer sequences and are repeatable sequence values. They are common in loops and can use specialized bytecode when the compiler proves i64 bounds.

Syntax

start..end excludes the end value. start..=end includes it.

fn sum_to(limit: i64) -> i64 {
    let total = 0
    for value in 0..=limit {
        total += value
    }
    return total
}

Iteration

Ranges are repeatable, so each for loop creates a fresh traversal. Indexed loops can still be used when both the index and value are needed.

fn weighted(limit: i64) -> i64 {
    let total = 0
    for index, value in 1..limit {
        total += index * value
    }
    return total
}

Methods

Ranges support standard methods such as len() and is_empty() where the bounds make those operations meaningful.

Performance Boundary

The VM may lower proven integer range loops to typed scalar bytecode. That optimization must preserve the same observable behavior and does not change the language model.