Getting started

Install the compiler with the script for your platform. The install page has both, and both verify the archive against the release checksums before they unpack anything.

Then run a file. vyrn run compiles the program to WebAssembly and runs it, and needs nothing else on your machine. vyrn build --target wasm writes that module. vyrn build puts the same bytes through wasm2c and clang into a native binary.

Both are the same program. The route harness runs every example both ways and compares the bytes, so a program that runs as wasm runs the same way as a binary.

A program is a file. main returns the exit code, and print writes one line to standard output.

Every program in this book has the same shape: a demo function that answers with the text, and the main that prints it. That is not a language rule. Follow the run link to open the same source in the playground.

// `demo` answers with the text. `main` below prints it and returns the exit code.
export fn demo() -> String {
    return "hello, world"
}

fn main() -> Int64 {
    print(demo())
    return 0
}

A function states the type of each parameter and the type it returns. Nothing is inferred across a function boundary, so a signature is the whole contract.

\{ } inside a string puts a value into it. The value is converted where it is written, not by a format string somewhere else.

// A function takes typed parameters and returns a typed result. `\{...}` puts a
// value into a string.
fn area(width: Int64, height: Int64) -> Int64 {
    return width * height
}

export fn demo() -> String {
    let w = 3
    let h = 4
    return "\{w} by \{h} is \{area(w, h)}"
}

fn main() -> Int64 {
    print(demo())
    return 0
}