Returning Values

The functions we’ve written so far perform actions but don’t give anything back to the caller. In practice, you’ll often want a function to compute something and return the result.

Declaring a Return Type

To indicate that a function returns a value, add a colon and a type after the parameter list:

function double(x: int): int
    int result = x + x
    return result
end

The : int after the parentheses tells the compiler this function gives back an integer. The return keyword sends the value to the caller.

To use the returned value, assign the function call to a variable:

int answer = double(21)
// answer is 42

Early Return

return can appear anywhere in the function body. When reached, the function exits immediately — any code after it won’t run:

function clampWantedLevel(level: int): int
    if level < 0
    then
        return 0
    end
    if level > 6
    then
        return 6
    end
    return level
end

This function ensures the wanted level stays between 0 and 6. If the input is out of range, an early return provides the clamped value without reaching the rest of the code.

Returning Multiple Values

A function can return more than one value. List the types separated by commas:

function getScreenCenter(): int, int
    int x = 320
    int y = 224
    return x y
end

The caller provides variables for each returned value:

int cx, cy
cx, cy = getScreenCenter()

Returning Without a Value

A function that doesn’t declare a return type can still use return to exit early — it just doesn’t provide a value:

function giveReward(amount: int)
    if amount <= 0
    then
        return // nothing to do
    end
    add_score {player} 0 amount
    print_formatted_now "+$%d" 2000 amount
end