Collections (List & Map)

Wysna provides high-performance, built-in collection primitives: list[T] (dynamic arrays) and dict[K, V] (hash maps). Both obey pure value semantics via Automatic Reference Counting (ARC) and Copy-on-Write (CoW).

Lists (list[T])

A list is a contiguous, dynamically-sized array of elements of uniform type.

Creating and Modifying Lists

fn main() -> unit {
    # Initializing a list of integers
    let mut numbers = [10, 20, 30]

    # Appending elements
    numbers.append(40)
    numbers.append(50)

    # Length
    print("Count:", len(numbers))  # 5

    # Indexing
    print("First:", numbers[0])    # 10
    print("Last: ", numbers[len(numbers) - 1])  # 50

    # Updating an element
    numbers[1] = 99
    print("Updated:", numbers)     # [10, 99, 30, 40, 50]
}

Common List Methods

• list.append(item): Appends an element to the end of the list.
• list.pop() -> T?: Removes and returns the last element, or none if empty.
• len(list): Returns the current number of elements.

---

Dictionaries (dict[K, V])

A dict is an associative hash map storing key-value pairs. Keys must belong to predictable types (int, str, bool, or enum); floating-point keys are prohibited compile-time (W2010).

Initializing and Accessing Dictionaries

fn main() -> unit {
    let mut scores: dict[str, int] = {
        "alice": 95,
        "bob": 88,
    }

    # Inserting or updating a key
    scores["charlie"] = 92
    scores["alice"] = 100

    # Safe retrieval with fallback via .get()
    let bob_score = scores.get("bob") ?? 0
    print("Bob score:", bob_score)

    # Checking key existence via .get()
    if scores.get("david") != none {
        print("David is present")
    } else {
        print("David not found")
    }
}

Value Semantics with Dictionaries

Assigning a dictionary creates a shared view until modified via Copy-on-Write:

fn main() -> unit {
    let base = {"mode": "dark", "fontSize": "14"}
    let mut custom = base
    custom["fontSize"] = "16"

    print("Base:  ", base["fontSize"])    # 14
    print("Custom:", custom["fontSize"])  # 16
}