Hello World

Create a folder odin_course and a file hello.odin inside it.

package hello

import "core:fmt"

main :: proc() {
    fmt.println("Hellope!")
}

You can run the program using the command odin run .

$ odin run .
Hellope!

Explanation

I will give only a quick explanation of each line. Each chapter goes deeper and eventually towards full understanding.

package hello

Declare the package name hello. All odin files should start with a package declaration and all odin files in a folder should have the same package name.

import core::fmt

core is like a standard library of Odin. It contains utilties that we can use in our program. core:fmt Has the fmt.println which we use to print Hellope to the screen.

main :: proc() {
  // do something here
}

main is a procedure (or function). It is the entry point of the program. When you run odin run . inside a folder, Odin looks for the main procedure in all files in that folder and runs whatever is inside.

There should be only one main procedure.

Understanding ::

It is used to declare compile time constants. The compiler will copy paste all instances of main with whatever is on the right of ::.

For example:

LUCKY_NUMBER :: 7

main() :: proc() {
    fmt.println(LUCKY_NUMBER + 3)
}

The line fmt.println(LUCKY_NUMBER + 3) would be replaced by fmt.println(7 + 3).