Hello World

import "std/io";

int main() {
    io.write("Hello, world!\n");
    return 0;
}

Paste it into the playground and press Run, or save it as hello.kora and compile it:

kora hello.kora -o hello && ./hello

Either way it prints Hello, world!.

Line by line

• import "std/io"; pulls in the standard I/O module. Modules are imported by path and named after the last segment, so its functions are io.write, io.print, and io.input.
• int main() is the entry point. Every program starts at main, which returns an int exit code. Return types come first: int, then the name.
• io.write("Hello, world!\n"); writes a string to stdout with no trailing newline, hence the explicit \n. A string is an array of char (bytes). (io.print adds the newline for you.)
• return 0; exits with success.

Reading input

io.input returns a string?, an optional, because input can end. Handle the empty case before using the value:

import "std/io";

int main() {
    io.write("What is your name? ");
    let name = io.input();
    if (name == none) { return 1; }
    io.write("Hello, ");
    io.write(name!);
    io.write("!\n");
    return 0;
}

The ! force-unwraps the optional, safe here because the none case already returned. In the playground, type into the Standard input box.

Next

• Kora in 5 Minutes: the whole language in one pass.
• Standard Library: every module, with signatures and examples.