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Scheme-rs: Embedded Scheme for the Rust Ecosystem

github crates.io docs.rs

Scheme-rs is an implementation of the R6RS specification of the Scheme programming language that is designed to be embedded within sync and async Rust.

;; Example of a program that defines a variable via a datum received over a 
;; socket.
;; 
;; Requires the `async` and `tokio` features enabled.

(import (rnrs) (async))

(define-syntax expand-from-socket
  (lambda (x)
    (syntax-case x ()
      [(ctxt)
       (let ([listener (bind-tcp "0.0.0.0:8080")])
         (let-values ([(port addr) (accept listener)])
           (let* ([port (transcoded-port port (native-transcoder))]
                  [recvd-syntax (datum->syntax #'ctxt (get-datum port))])
             (write 'thanks! port)
             (close-port port)
             recvd-syntax)))])))

(define var-from-network (expand-from-socket))

Features:

  • Modern: scheme-rs is a modern scheme implementation of the R6RS standard and includes advanced features such as delimited continuations.
  • Fast: scheme-rs uses JIT compilation to provide performance on par with other modern scheme implementations.
  • Easy to use: scheme-rs makes it trivial to define Rust functions and data structures that are accessible from scheme code and vice-versa.
  • Safe: scheme-rs provides a completely safe API that is impossible to misuse.
  • Supports both async and sync Rust: by enabling the async feature flag it becomes possible (and easy) to define async scheme functions in Rust.

Getting started:

For embedding scheme-rs in your Rust project, take a look at the API documentation.

For installing scheme-rs as a standalone executable, cargo can be used:

$ cargo install scheme-rs

To enable async features, install with the async and tokio features:

$ cargo install scheme-rs --features "async,tokio"

Supported platforms:

scheme-rs uses cranelift for JIT compilation and is therefore limited to platforms supported by cranelift. At the current moment that includes x86-64, aarch64 (ARM64), s390x (IBM Z), and riscv64 architectures.

scheme-rs has been tested on the following platforms:

  • Linux (fully supported, primary platform)
  • MacOs (occasionally tested)
  • Windows (previously tested, not tested in a while)

Documentation

Contributing

If you have any questions or comments about the project, feel free to join the scheme-rs discord server.