Hello, World!

Let’s begin by writing and executing a minimal program in Wysna.

Creating the Source File

Create a file named main.wysna:

## main.wysna

fn greet(name: str) -> str {
    return "Hello, " + name + "! Welcome to Wysna."
}

fn main() -> unit {
    let message = greet("World")
    print(message)
}

---

Anatomy of the Program

Let’s break down each element of this program:

1. Comments: Comments begin with double hashes ## (or single # for inline comments).
2. Function Declaration (fn):
   • greet accepts a parameter name of type str and returns a str.
   • In Wysna, function parameter types and return types are explicit.
3. String Concatenation: Strings are managed buffers that support concatenation using the + operator with automatic ARC lifecycle tracking.
4. The main Entry Point:
   • Every executable program defines an entry point named main().
   • Its return type is unit (indicating no meaningful return value, analogous to void in C or () in Rust).
5. Immutable Variables (let):
   • let message = greet("World") binds message. By default, variables defined with let are immutable.
6. Built-in print:
   • print(...) writes formatted strings and values to standard output (stdout) followed by a newline.

---

Compiling and Running

You can compile and immediately execute the program with a single command:

wysna run main.wysna

Output:

Hello, World! Welcome to Wysna.

Compiling to a Standalone Executable

To produce a native binary file for distribution:

wysna build main.wysna -o app
./app