Control Flow

Loops

Latimer supports two primary looping constructs: for and while.

For

A for loop is typically used when the number of iterations is known ahead of time. It includes an initializer, a condition, and an increment expression—all written in the loop header.

for (int i = 0; i < 5; i = i + 1) {
    print(i);
}
// Prints: 0 1 2 3 4

The loop works as follows:

1. int i = 0 initializes the loop variable.
2. i < 5 is the condition; the loop continues as long as this is true.
3. i = i + 1 runs after each iteration to update the loop variable.

All three components are optional. For example, you can declare i outside the loop:

int i = 0;
for (; i < 3; i = i + 1) {
    print(i);
}

While

A while loop is used when the condition must be checked before every iteration, and the number of repetitions is not necessarily known in advance.

int x = 1;
while (x < 100) {
    print(x);
    x = x * 2;
}
// Prints: 1 2 4 8 16 32 64

The loop works as follows:

1. The condition x < 100 is evaluated before each iteration.
2. If it’s true, the loop body runs.
3. If it’s false, the loop exits.

Break

The break statement is used to exit the nearest enclosing loop immediately. Execution continues with the first statement after the loop.

for (int i = 0; i < 10; i = i + 1) {
    if (i == 5) {
        break;
    }
    print(i);
}
// Prints: 0 1 2 3 4

The loop terminates early when the condition inside the if statement is met. After break is executed, control moves to the first statement following the loop.

Continue

The continue statement skips the rest of the current loop iteration and proceeds to the next one.

for (int i = 0; i < 5; i = i + 1) {
    if (i == 2) {
        continue;
    }
    print(i);
}
// Prints: 0 1 3 4

Here, when i is 2, the print statement is skipped, and the loop immediately proceeds to the next iteration.

Conditionals

Latimer supports conditional branching using if, else if, and else statements.

If

An if statement takes an expression that evaluates to a boolean value. If the condition is true, the program executes the statement block inside the if.

int temp_fahrenheit = 30;
if (temp_fahrenheit <= 32) {
    print("It's very cold. Consider wearing a scarf.");
}
// Prints "It's very cold. Consider wearing a scarf."

In the example above, the program checks whether the temperature is less than or equal to 32 degrees Fahrenheit (the freezing point of water). Since it is, the message is printed. Otherwise, execution continues after the closing brace of the if block.

The if statement can include an optional else clause to execute an alternative block when the condition is false.

temp_fahrenheit = 40;
if (temp_fahrenheit <= 32) {
    print("It's very cold. Consider wearing a scarf.")
} else {
    print("It's not that cold. Wear a T-shirt.")
}
// Prints "It's not that cold. Wear a T-shirt."

In this case, because the temperature is 40, the else block is executed instead.

You can also chain multiple conditions using else if:

temp_fahrenheit = 90;
if (temp_fahrenheit <= 32) {
    print("It's very cold. Consider wearing a scarf.")
} else if (temp_fahrenheit >= 86) {
    print("It's really warm. Don't forget to wear sunscreen.")
} else {
    print("It's not that cold. Wear a T-shirt.")
}
// Prints "It's really warm. Don't forget to wear sunscreen."

Here, the else if condition is triggered when the temperature is 90. The else clause serves as a fallback for values that don’t match any previous conditions.

The final else clause is optional and can be omitted if no fallback behavior is needed:

temp_fahrenheit = 72;
if (temp_fahrenheit <= 32) {
    print("It's very cold. Consider wearing a scarf.")
} else if (temp_fahrenheit >= 86) {
    print("It's really warm. Don't forget to wear sunscreen.")
}

In this case, none of the conditions match, so the program continues without printing anything.