// Calls can also generate results, using 'reply'.
:(scenario "reply")
recipe main [
  3:integer, 4:integer <- f 2:literal
]
recipe f [
  12:integer <- next_ingredient
  13:integer <- add 1:literal, 12:integer
  reply 12:integer, 13:integer
]
+run: instruction main/0
+run: result 0 is 1[2...]
+mem: storing in location 3
+run: result 1 is 1[3...]
+mem: storing in location 4

:(before "End Globals")
const int REPLY = 23;
:(before "End Primitive Recipe Numbers")
Recipe_number["reply"] = REPLY;
assert(Next_recipe_number == REPLY);
Next_recipe_number++;
:(before "End Primitive Recipe Implementations")
case REPLY: {
  vector<vector<int> > callee_results;
  for (size_t i = 0; i < instructions[pc].ingredients.size(); ++i) {
    callee_results.push_back(read_memory(instructions[pc].ingredients[i]));
  }
  rr.calls.pop();
  size_t& caller_pc = rr.calls.top().pc;
  instruction& caller_instruction = Recipe[rr.calls.top().running_recipe].steps[caller_pc];
  assert(caller_instruction.products.size() <= callee_results.size());
  for (size_t i = 0; i < caller_instruction.products.size(); ++i) {
    trace("run") << "result " << i << " is " << callee_results[i].size() << "[" << callee_results[i][0] << "...]";
    write_memory(caller_instruction.products[i], callee_results[i]);
  }
  ++caller_pc;
  break;
}