The Crow Programming Language
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Getting Started

Let's install Crow, meet the toolchain, and run your first program. By the end of this chapter you'll have both execution modes working and a project directory ready for the rest of the book.

Installation

You need a Mac or a Linux machine (on Windows, run everything inside WSL), git, and about ten minutes, most of it compiling. One command from a fresh clone does the rest:

git clone https://github.com/agncrow/crow.git
cd crow
./install.sh

Crow compiles your programs to Rust, so the Rust toolchain is a real dependency, not just a build-time one — and the script takes care of it. It installs whatever is missing and skips whatever is present, in order:

  1. A C toolchain. The Xcode Command Line Tools on macOS (a dialog opens; accept it), gcc through your package manager on Linux.
  2. Rust, through rustup — stable, no prompts. Crow needs 1.85 or newer.
  3. A permanent home. The source is copied to ~/.crow/src. Compiled programs link against the runtime crates there, so the clone can go once the script is done, and re-running the script on a newer checkout is the upgrade.
  4. The binary, built in release mode into ~/.cargo/bin/crow. The first build takes a few minutes.
  5. Proof. A hello project is created, compiled, and run.

./install.sh --dev builds from the checkout in place instead — for working on Crow itself, since compiled programs then link against your working tree. --quick skips the proof; --uninstall removes the binary and ~/.co and leaves Rust alone. On Windows, run it inside WSL.

If this was your first Rust install, open a new terminal (rustup put ~/.cargo/bin on your PATH through your shell profile), then verify:

crow -v

You should see the version. crow on its own starts the REPL, and crow help lists run, build, new, fmt, check, and test.

If something goes wrong

  • crow: command not found right after the install: the binary is in ~/.cargo/bin, which a fresh Rust install adds to your shell profile. Open a new terminal, or run source "$HOME/.cargo/env" in this one.
  • A dialog appeared on macOS. That is the Command Line Tools installer; accept it. The script waits for it to finish.
  • Linux asked for a password. Installing the C compiler goes through your package manager with sudo. Nothing else in the script needs it.
  • It seems stuck on "building crow". A release build of the compiler takes a few minutes the first time and is quiet while it runs. Later runs reuse the cache in ~/.crow/target.
  • Upgrading: git pull, then ./install.sh again. Removing: ./install.sh --uninstall.

Editor Support

Crow ships its own language server — diagnostics as you type, completions with inferred signatures, hover types, go-to-definition — as a subcommand of the same binary you just installed:

crow lsp

You never run that yourself; your editor does. For VS Code, build and install the extension once:

cd editors/vscode && npm install && npx @vscode/vsce package --allow-missing-repository
code --install-extension crow-lang-0.1.0.vsix

Neovim, Helix, and Zed speak LSP natively — copy the snippet for your editor from docs/crow-lsp.md. Everything the editor shows comes from the real compiler pipeline, so the squiggles never disagree with crow run.