Hello World¶

Code¶

// This is a comment. Comments don't do anything.
// Comments begin with `//` and continue until the end of the line.
fn main() { // This is another comment!
    print("Hello, world!");
}

Breakdown¶

The heart of every Keel file is the main function, it's the entry point of your program. Any Keel file used as the program's entry point must define a main function.

fn is the keyword used to declare the function. main is the name of the function. () indicates that our function doesn't take any arguments as input (more on functions and function arguments in Functions.).
We then use curly braces to enclose the function's code. You'll encounter curly braces pretty much everywhere, as they're used to enclose 'blocks'.
Then, we print "Hello, world!". To do that, we call the print function which takes a String as input, and prints it to the terminal. We end the line with a semicolon.