Scuzz Lang

Scuzz is a functional programming language for native applications. It takes inspiration from Scala’s concise syntax and Flutter’s approach to user interfaces.

Scuzz includes a compiler, a UI toolkit, and command-line tools to build, run, format, and verify apps. It targets command-line tools, servers, desktop apps, and mobile apps. GUI apps can also run in a browser through WebAssembly.

Scuzz is in active development. See Status and platforms for current support and limits.

Why Scuzz?

• Native applications. Write concise, functional code that compiles to native binaries through LLVM.
• An integrated UI toolkit. Build interfaces with shared app code. Use hot reload to update a UI while it runs.
• UI automation. Run UI apps without a display. Record and replay input for debugging and testing.
• Built-in verification. Define properties that your code must satisfy. Use fuzzing, mutation testing, and deterministic simulation to check them.
• One toolchain. Use scuzz to build, run, format, check, fuzz, and package apps. The standard library covers common app tasks.

Scuzz takes inspiration from Scala but does not support Scala or JVM libraries. See the compatibility details.

A small example

This Counter displays a number and a button. Each click adds one to the number.

@main def main: IO[Unit] =
  for {
    count = Signal.make(0)
    label = Signal.map(count, n => s"count = $n")
    _ <- Ui.run(_ => View.column(
      View.text("Counter"),
      View.bindText(label),
      View.button("+1", _ => Signal.set(count, Signal.get(count) + 1))
    ))
  } yield ()

A Signal holds a value that can change. The label updates when the count changes. A View describes the interface. Ui.run runs the interface through IO, which represents effects such as user interaction and file access.

Create a Counter project with the commands below. The generated app includes verification code. For a larger app with pages and saved tasks, see Studio.

Install and run

Release packages support Linux x86-64 and macOS Apple Silicon. App builds need clang and make. Linux also needs the zlib, bzip2, and OpenSSL development packages. See host setup for package commands. The installer does not install these tools or libraries.

curl -fsSL https://github.com/SeanCheatham/scuzz/releases/latest/download/install.sh | sh
export PATH="$HOME/.local/bin:$PATH"

The script installs Scuzz under ~/.local/share/scuzz. It puts the scuzz command in ~/.local/bin. Add the PATH line to your shell configuration to use it in new terminals.

Create and run a Counter app:

scuzz new myapp --ui
cd myapp
scuzz run --target headless --exec ""

Headless mode runs the interface without a window. --exec "" plays no ops and exits after the first paint. Drop --exec to keep the session live, then drive it with scuzz exec. To open a desktop window, set default_runtime = "desktop" in the [ui] section of scuzz.toml, then run scuzz run. Linux desktop apps need X11 and its development libraries. Close the window to exit.

For a command-line app, omit --ui when you create the project, then use scuzz run.

Explore the tools

Run these commands from your app directory:

scuzz fmt
scuzz check
scuzz fuzz --iterations 100

These commands format the source, check the code, and run a verification campaign. Fuzzing searches for property failures. Mutation testing checks whether the properties detect changes to the code.

Use scuzz run --watch for UI hot reload. Use scuzz ide . to open the bundled editor in a desktop window.

Status and platforms

The compiler and command-line tools are written in Scuzz. Platform support has these limits:

Platform	Current support
Linux	Native apps, headless UI, and X11 desktop windows. Release package for x86-64.
macOS	Native apps and desktop windows. Release package for Apple Silicon.
Android and iOS	Packaging tools and platform shells. Android needs the NDK. iOS needs Xcode. Hardware device checks remain open.
Browser	WebAssembly GUI apps. Native network and process effects are unavailable. Files do not persist across page reloads.
Windows	Desktop support is planned.

See compatibility for platform details and known gaps for open work.

Learn more and contribute

• Read the hosted docs: open scuzz.build.
• Start building: run scuzz docs start after installation.
• Learn the language: run scuzz docs language.
• Build interfaces: run scuzz docs gui.
• Write properties: run scuzz docs verify.
• Browse working code: see the examples.
• Understand the direction: read the product philosophy and the planning arcs.
• Report a problem or suggest a change: open a GitHub issue.
• Work on Scuzz: follow the checkout setup.

License

Apache-2.0