Control Flow

Wysna provides structured control flow primitives: conditionals (if / elif / else), loops (for in, while), and exhaustive pattern matching (match).

Conditional Branching (if / elif / else)

Conditionals evaluate boolean expressions without requiring surrounding parentheses. Use elif for chained branches:

fn assess_score(score: int) -> str {
    if score >= 90 {
        return "Excellent"
    } elif score >= 70 {
        return "Good"
    } else {
        return "Needs Improvement"
    }
}

Because if blocks can act as expressions in statement positions, all branches must return compatible types.

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Loop Expressions

for in Loops and Ranges

Wysna includes first-class range syntax:

• 0..limit: Half-open range (from 0 up to, but not including, limit).
• 1..=limit: Inclusive range (from 1 up to and including limit).

fn main() -> unit {
    # Summing numbers 1 through 10
    let mut total = 0
    for i in 1..=10 {
        total = total + i
    }
    print("Total:", total)

    # Iterating over lists
    let items = ["apple", "banana", "orange"]
    for fruit in items {
        print("Fruit:", fruit)
    }

    # Iterating with index
    for idx, fruit in enumerate(items) {
        print(idx, fruit)
    }
}

while Loops

Use while for condition-driven iteration:

fn countdown(start: int) -> unit {
    let mut current = start
    while current > 0 {
        print(current)
        current = current - 1
    }
    print("Liftoff!")
}

break and continue

Inside any loop, use break to terminate early and continue to jump directly to the next iteration:

fn find_first_even(numbers: list[int]) -> int {
    let mut found = -1
    for n in numbers {
        if n % 2 != 0 {
            continue
        }
        found = n
        break
    }
    return found
}