λ Marwood  

Marwood is an embeddable Scheme R7RS implementation, featuring:

• a scheme R7RS compiler & 64 bit runtime
• a terminal based repl using rustyline
• a WebAssembly repl at repl.marwood.io.

And these scheme language features:

• most R7RS language and library features
• Tail call optimization
• First class continuations (call/cc)
• Support for scheme's numerical tower, including rationals
• Partial support for syntax-rules

Example

The adder example creates a procedure called make-adder, which given an argument x returns a procedure that adds its own argument y to x.

This example may be executed with cargo run --example adder.

Here's the scheme that will execute in the VM given the rust example:

(define make-adder 
    (lambda (x) 
        (lambda (y) (+ x y))))
(define add-1000 
    (make-adder 1000))
    
(add-1000 0)
(add-1000 1)
(add-1000 2)
(add-1000 3)
(add-1000 4)

And the rust code to execute the scheme above in marwood:

let mut vm = Vm::new();

vm.eval_text("(define make-adder (lambda (x) (lambda (y) (+ x y))))")
    .unwrap();
vm.eval_text("(define add-1000 (make-adder 1000))")
    .unwrap();

for it in 0..5 {
    match vm.eval(&list!["add-1000", it]) {
        Ok(result) => {
            println!("{} => {}", it, result);
            assert_eq!(result, cell![1000 + it])
        }
        Err(e) => error!("error: {}", e),
    }
}

License

Licensed under either of Apache License, Version 2.0 or MIT license.