FlyCloudC/scheme

A Scheme interpreter implemented in Moonbit. It will be used for teaching purposes and not too many optimizations will be added. The understandability of the code is given top priority.

Reference:

• Three Implementation Models for Scheme Chapter 3 The Heap-Based Model

• Structure and Interpretation of Computer Programs

example

test "example in README" {
  let env = Environment::base()
  env.add_number_primitive()
  let code =
    #|(define (fact x)
    #|   (if (= x 0)
    #|       1                      ; base case
    #|       (* x (fact (- x 1))))) ; rec case
    #|(fact 5)
  let sexp : Array[Value] = parse(code)
  let program : Array[CoreForm] = sexp.map(Value::to_core_form)
  let inst : Array[Inst] = program.map(compile)

  // make VM, load "(define (fact x) ...)" and env
  let vm = VM::new(inst=inst[0], env~)

  // run, add "fact" to env
  vm.run_to_halt()
  inspect(
    vm.env.lookup(@symbol.Symbol::of("fact")),
    content="#<procedure fact>",
  )

  // load and run "(fact 5)"
  vm.next = inst[1]
  vm.run_to_halt()
  inspect(vm.acc, content="120")
}