1. Installing, and the first program

You need JDK 21 (native compilation additionally needs GraalVM). bin/dawn brings up its own toolchain: on the first run it downloads the dawn-selfhost.jar of the release pinned by scripts/seed-release.txt (the seed, checked against scripts/seed-checksums.txt by SHA-256), then uses the seed to compile selfhost/ into the current compiler. There is no Gradle — the Kotlin implementation is archived at the kotlin-final tag, and ./gradlew :compiler:fatJar does not exist on main.

./bin/dawn --version              # the first run fetches the seed and rebuilds the toolchain
./bin/dawn run  hello.dawn        # compile and run (on the JVM)
./bin/dawn test hello.dawn        # run the test blocks in the file
./bin/dawn build hello.dawn --native -o hello   # produce a standalone binary

The first program. Functions are pure by default; touching IO — printing, here — requires !io on the signature:

pub fn main() -> Unit !io =
  println("Hello, Dawn")

Hello, Dawn

String interpolation is introduced by $: $name interpolates a plain variable, ${expr} any expression (the value interpolated has to be printable). Braces on their own are ordinary characters — without a $ there is no interpolation:

pub fn main() -> Unit !io = {
  let name = "Dawn"
  let year = 2026
  println("$name was born in $year")
}

Dawn was born in 2026