1. Hello, Resilient

Install the compiler, run your first program, pick a backend.

Install

Pick the path that fits — see Getting Started for the full menu. The shortest path:

curl -fsSL https://raw.githubusercontent.com/EricSpencer00/Resilient/main/scripts/install.sh | bash
# Then add ~/.rz/bin to $PATH (the script prints the line for your shell).
rz --version

If you have Rust locally and prefer to build from source:

git clone https://github.com/EricSpencer00/Resilient.git
cd Resilient
cargo install --path resilient
# `rz` lands in ~/.cargo/bin/rz

If you don’t want anything local, the Docker image is a one-liner:

docker run --rm ghcr.io/ericspencer00/resilient:latest --help

Your first program

Open hello.rz and paste:

fn main() {
    println("Hello, Resilient world!");
}
main();

Then run it:

rz hello.rz

You should see:

Hello, Resilient world!
Program executed successfully

Two things worth calling out:

  • The file ends in .rz. Resilient source uses the .rz extension. Install the VS Code extension for syntax highlighting and one-click run.
  • main(); at the bottom. Functions declared with fn are not auto-invoked. The last line kicks off execution. If you forget it, the program runs fine but doesn’t print anything.

Three backends

Resilient ships with three execution modes: a tree-walking interpreter (default, most features), a bytecode VM (--vm, faster on hot loops), and a Cranelift JIT (--jit, native machine code for the numeric-heavy subset).

For the same program:

fn fib(int n) -> int {
    if n < 2 { return n; }
    return fib(n - 1) + fib(n - 2);
}
fn main() {
    println(fib(20));
}
main();

Save as fib.rz and run through each:

rz fib.rz          # tree-walker (default)
rz --vm fib.rz     # bytecode VM
# JIT needs a feature-flagged build:
cargo install --path resilient --features jit  # one-time
rz --jit fib.rz

All three print 6765. The walker is a few hundred ms; the VM shaves ~30x; the JIT drops into the sub-millisecond range. The performance page has the numbers.

What you learned

  • fn, println, and the main(); call-site idiom.
  • How to run a .rz file with rz.
  • That there are three backends; you can pick the one that fits your workload.

What’s next

→ 2. Variables and types