How do I embed Starlark in my Rust app?

Use the main starlark library to integrate Starlark by defining custom types and functions in Rust, then embed the evaluator; the README suggests writing your own binary for domain-specific features.

Starlark-rust vs Starlark-go for a new project?

Choose Starlark-rust if you're embedding in Rust for best interoperability; opt for Starlark-go if you're in a Go ecosystem. Starlark-rust offers better Rust integration but has less stable APIs compared to the more mature Go version.

Does starlark-rust work with VS Code?

Yes, it supports IDE integration via LSP, and there's a VS Code extension mentioned in the README, but for custom bindings, you may need to build your own language server.

How can I debug Starlark scripts in Rust?

Leverage the Debug Adapter Protocol (DAP) support in the library to set up debugging; however, this requires integrating the debugger with your custom binary for full functionality.

Is the starlark-rust API stable for production?

No, the project explicitly does not aim for API stability between releases, preferring rapid iteration, so frequent updates might break compatibility in production environments.

How to add custom functions in starlark-rust?

Define Rust functions and use the starlark library to expose them as Starlark callables, but you'll likely need to create a custom binary or integration layer, as the standard binary lacks domain-specific bindings.

Open-Awesome

starlark-rust

Apache-2.0Rustv0.13.0

A Rust implementation of the Starlark language, used for configuration in build systems like Bazel and Buck.

GitHub

963 stars92 forks0 contributors

What is starlark-rust?

Starlark in Rust is a library that provides a Rust implementation of the Starlark language. Starlark is a deterministic, Python-like language used primarily for configuration in build systems such as Bazel, Buck, and Buck2. This library allows developers to embed Starlark within Rust applications, enabling scripting and configuration capabilities.

Target Audience

Rust developers who need to embed a scripting or configuration language in their applications, particularly those working on build tools, development tools, or systems requiring extensible configuration.

Value Proposition

It offers seamless interoperability between Rust and Starlark, along with features like garbage collection, type checking, and IDE support, making it a robust choice for embedding Starlark in Rust ecosystems.

Overview

A Rust implementation of the Starlark language

Use Cases

Best For

Embedding a configuration language in Rust-based build tools
Adding scripting capabilities to Rust applications
Creating extensible configuration systems for development tools
Implementing Starlark support in custom build systems
Building IDE plugins or language servers for Starlark
Developing linters or debuggers for Starlark code

Not Ideal For

Projects requiring stable, long-term API compatibility
Applications with strict minimal dependency requirements
Teams needing full Starlark spec support including newer features like bytes
Users looking for a standalone Starlark interpreter in non-Rust environments

Pros & Cons

Pros

Seamless Rust Integration

Offers easy conversion between Rust types and Starlark values, enabling smooth embedding and extension in Rust applications, as highlighted in the README's interoperability features.

Advanced Developer Tooling

Includes Language Server Protocol (LSP) for IDE support and Debug Adapter Protocol (DAP) for debugging, enhancing the development experience for Starlark scripts.

Robust Testing Suite

Features extensive testing, including fuzz testing, which ensures reliability and stability across various use cases, as mentioned in the project's testing goals.

Optional Type Safety

Provides runtime-checked types for enhanced safety, allowing developers to add type annotations to Starlark code, which is documented in the types section.

Cons

Unstable API

Prioritizes rapid iteration over API stability, making it challenging for projects that require long-term compatibility, as stated in the non-goals section.

Heavy Dependency Footprint

Opts for a feature-rich single package rather than minimizing dependencies, which can bloat projects, as admitted in the README's dependency philosophy.

Incomplete Spec Compliance

Lacks support for some Starlark features like bytes, limiting compatibility with scripts that use newer spec elements, as noted in the compatibility section.

Complex Custom Integration

Requires building a custom binary for domain-specific bindings, since the provided starlark_bin only supports standard Starlark, adding overhead for tailored use cases.

Frequently Asked Questions

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