• Hello world
• Fibonacci numbers
• Reading from standard input
• Reading from a file
• Writing to a file
• Run a shell command
• Guessing game
• FizzBuzz
• Iterating over a string
• Iterating over a range

Hello world

You can echo any value to the standard output stream:

echo "hello world";

Pyro also has a family of $print() functions:

$println("hello world");

You can use format strings with these functions to interpolate variables:

var target = "world";
$println("hello {}", target);

Fibonacci numbers

Calculate the n-th Fibonacci number:

def fib(n) {
    if n < 2 {
        return n;
    }
    return fib(n - 1) + fib(n - 2);
}

Reading from standard input

Read a single line from the standard input stream:

var line = $input();

Read in a loop from the standard input stream:

loop {
    $print(">>> ");
    var line = $input();

    if line == null || line == "exit" {
        break;
    }

    echo "input was: " + line;
}

Reading from a file

Read the content of a file into a string:

var string = $read_file("input.txt");

This is a convenience function — a $file object provides more fine-grained control:

var file = $file("input.txt", "r");
var string = file:read_string();
file:close();

Writing to a file

Write a string to a file:

$write_file("output.txt", "Content for file...");

This is a convenience function — a $file object provides more fine-grained control:

var file = $file("output.txt", "w");
file:write("Content for file...");
file:close();

Run a shell command

The $shell() function takes a string arugment specifying the command to run. It returns a two-item tuple containing the exit code as an integer and the output as a string:

var (code, output) = $shell("pwd");

Guessing game

The classic guess-a-random-number game:

var target = $std::prng::rand_int(10) + 1;

loop {
    $print("Enter a number between 1 and 10: ");

    var guess = $input();
    if guess == null || guess == "exit" {
        break;
    }

    if guess == $str(target) {
        echo "Correct!";
        break;
    } else {
        echo "Wrong! Try again...";
    }
}

FizzBuzz

The classic interview question:

def fizzbuzz(n) {
    for i in $range(1, n + 1) {
        if i % 15 == 0 {
            echo "fizzbuzz";
        } else if i % 3 == 0 {
            echo "fizz";
        } else if i % 5 == 0 {
            echo "buzz";
        } else {
            echo i;
        }
    }
}

Iterating over a string

A string is a sequence of bytes. You can iterate over these individual byte values using the :bytes() method:

for byte in "hello":bytes() {
    echo byte;
}

This gives the following output:

104
101
108
108
111

Alternatively, you can interpret the string as a sequence of UTF-8 encoded characters and iterate over these characters using the :chars() method:

for char in "hello":chars() {
    echo char;
}

This gives the following output:

h
e
l
l
o

Iterating over a range

The $range() function returns an iterator over a range of integers:

for i in $range(5) {
    echo i;
}

This gives the following output:

0
1
2
3
4