sclass Operation {

  S function;

  int[] registers;

  int outRegister = -1;

  *(S *function, int... regs) {

    registers = subArray(regs, 0, l(regs)-1);

    outRegister = last(regs);

  }

}

sclass Machine {

  O[] registers = new O[10];

  new TreeMap<S, O> functions;

  void function(S name, O implementation) {

    functions.put(name, implementation);

  }

  void set(int register, O value) {

    if (register >= l(registers))

      registers = resizeArray(registers, register+1);

    registers[register] = value;

  }

  O get(int register) {

    ret _get(registers, register);

  }

  void run(Operation op) {

    O f = functions.get(op.function);

    if (f == null) fail("Unknown operation: " + op.function);

    int n = l(op.registers);

    O[] arguments = new O[n];

    for i to n: arguments[i] = get(op.registers[i]);

    O result = callF(f, arguments);

    if (op.outRegister >= 0)

      set(op.outRegister, result);

  }

}