var count: int = 0;
var isDark: bool = false;

proc updateUI() {
    writeln("Counter: ", count);
    writeln("Theme: ", if isDark then "Dark" else "Light");
}

proc increment() {
    count += 1;
    updateUI();
}

proc decrement() {
    count -= 1;
    updateUI();
}

proc reset() {
    count = 0;
    updateUI();
}

proc toggleTheme() {
    isDark = !isDark;
    updateUI();
}

// Simulate actions
updateUI();
increment();
increment();
toggleTheme();
decrement();
reset();

Demonstrates a simple counter with theme toggling using Chapel variables, procedures, and I/O.

var a: int = 0;
var b: int = 1;
writeln(a);
writeln(b);
for i in 1..8 {
    var c = a + b;
    writeln(c);
    a = b;
    b = c;
}

Generates first 10 Fibonacci numbers using an iterative approach.

proc factorial(n: int): int {
    if n == 0 then return 1;
    return n * factorial(n-1);
}
writeln(factorial(5));

Calculates factorial of a number using recursion.

proc isPrime(n: int): bool {
    if n < 2 then return false;
    for i in 2..n-1 {
        if n % i == 0 then return false;
    }
    return true;
}
writeln(if isPrime(13) then "Prime" else "Not Prime");

Checks if a number is prime.

var nums = [1,2,3,4,5];
var sum = 0;
for n in nums do sum += n;
writeln(sum);

Calculates sum of an array of numbers.

var s = "HELLO";
var r = s.reversed();
writeln(r);

Reverses a string.

var n = 5;
for i in 1..10 do writeln(n, " x ", i, " = ", n*i);

Prints multiplication table of a number.

var c: real = 25.0;
var f = (c * 9.0/5.0) + 32.0;
writeln(f);

Converts Celsius to Fahrenheit.

var temp = 80;
var thresh = 75;
writeln(if temp > thresh then "Alarm: Temperature Too High!" else "Temperature Normal");

Simulates an alarm if a threshold is exceeded.

var steps = 10;
var pos = 0;
for i in 1..steps {
    if random(0,1) < 0.5 then pos += 1 else pos -= 1;
    writeln(pos);
}

Simulates a 1D random walk.