//: Calls can also generate products, using 'reply' or 'return'.
:(scenario return)
def main [
1:num, 2:num <- f 34
]
def f [
12:num <- next-ingredient
13:num <- add 1, 12:num
return 12:num, 13:num
]
+mem: storing 34 in location 1
+mem: storing 35 in location 2
:(scenario reply)
def main [
1:num, 2:num <- f 34
]
def f [
12:num <- next-ingredient
13:num <- add 1, 12:num
reply 12:num, 13:num
]
+mem: storing 34 in location 1
+mem: storing 35 in location 2
:(before "End Primitive Recipe Declarations")
RETURN,
:(before "End Primitive Recipe Numbers")
put(Recipe_ordinal, "return", RETURN);
put(Recipe_ordinal, "reply", RETURN); // synonym while teaching
put(Recipe_ordinal, "output", RETURN); // experiment
:(before "End Primitive Recipe Checks")
case RETURN: {
break; // checks will be performed by a transform below
}
:(before "End Primitive Recipe Implementations")
case RETURN: {
// Begin Return
if (Trace_stream) {
trace("trace") << current_instruction().name << ": decrementing callstack depth from " << Trace_stream->callstack_depth << end();
--Trace_stream->callstack_depth;
if (Trace_stream->callstack_depth < 0) {
Current_routine->calls.clear();
goto stop_running_current_routine;
}
}
Current_routine->calls.pop_front();
// just in case 'main' returns a value, drop it for now
if (Current_routine->calls.empty()) goto stop_running_current_routine;
for (int i = 0; i < SIZE(ingredients); ++i)
trace(9998, "run") << "result " << i << " is " << to_string(ingredients.at(i)) << end();
// make return products available to caller
copy(ingredients.begin(), ingredients.end(), inserter(products, products.begin()));
// End Return
break; // continue to process rest of *caller* instruction
}
//: Types in return instructions are checked ahead of time.
:(before "End Checks")
Transform.push_back(check_types_of_return_instructions); // idempotent
:(code)
void check_types_of_return_instructions(const recipe_ordinal r) {
const recipe& caller = get(Recipe, r);
trace(9991, "transform") << "--- check types of return instructions in recipe " << caller.name << end();
for (int i = 0; i < SIZE(caller.steps); ++i) {
const instruction& caller_instruction = caller.steps.at(i);
if (caller_instruction.is_label) continue;
if (caller_instruction.products.empty()) continue;
if (is_primitive(caller_instruction.operation)) continue;
const recipe& callee = get(Recipe, caller_instruction.operation);
for (int i = 0; i < SIZE(callee.steps); ++i) {
const instruction& return_inst = callee.steps.at(i);
if (return_inst.operation != RETURN) continue;
// check types with the caller
if (SIZE(caller_instruction.products) > SIZE(return_inst.ingredients)) {
raise << maybe(caller.name) << "too few values returned from " << callee.name << '\n' << end();
break;
}
for (int i = 0; i < SIZE(caller_instruction.products); ++i) {
reagent/*copy*/ lhs = return_inst.ingredients.at(i);
reagent/*copy*/ rhs = caller_instruction.products.at(i);
// End Check RETURN Copy(lhs, rhs)
if (!types_coercible(rhs, lhs)) {
raise << maybe(callee.name) << return_inst.name << " ingredient '" << lhs.original_string << "' can't be saved in '" << rhs.original_string << "'\n" << end();
raise << " ['" << to_string(lhs.type) << "' vs '" << to_string(rhs.type) << "']\n" << end();
goto finish_return_check;
}
}
// check that any return ingredients with /same-as-ingredient connect up
// the corresponding ingredient and product in the caller.
for (int i = 0; i < SIZE(caller_instruction.products); ++i) {
if (has_property(return_inst.ingredients.at(i), "same-as-ingredient")) {
string_tree* tmp = property(return_inst.ingredients.at(i), "same-as-ingredient");
if (!tmp || !tmp->atom) {
raise << maybe(caller.name) << "'same-as-ingredient' metadata should take exactly one value in '" << to_original_string(return_inst) << "'\n" << end();
goto finish_return_check;
}
int ingredient_index = to_integer(tmp->value);
if (ingredient_index >= SIZE(caller_instruction.ingredients)) {
raise << maybe(caller.name) << "too few ingredients in '" << to_original_string(caller_instruction) << "'\n" << end();
goto finish_return_check;
}
if (!is_dummy(caller_instruction.products.at(i)) && !is_literal(caller_instruction.ingredients.at(ingredient_index)) && caller_instruction.products.at(i).name != caller_instruction.ingredients.at(ingredient_index).name) {
raise << maybe(caller.name) << "'" << to_original_string(caller_instruction) << "' should write to '" << caller_instruction.ingredients.at(ingredient_index).original_string << "' rather than '" << caller_instruction.products.at(i).original_string << "'\n" << end();
}
}
}
finish_return_check:;
}
}
}
bool is_primitive(recipe_ordinal r) {
return r < MAX_PRIMITIVE_RECIPES;
}
:(scenario return_type_mismatch)
% Hide_errors = true;
def main [
3:num <- f 2
]
def f [
12:num <- next-ingredient
13:num <- copy 35
14:point <- copy 12:point/raw
return 14:point
]
+error: f: return ingredient '14:point' can't be saved in '3:num'
//: In Mu we'd like to assume that any instruction doesn't modify its
//: ingredients unless they're also products. The /same-as-ingredient inside
//: the recipe's 'return' indicates that an ingredient is intended to be
//: modified in place, and will help catch accidental misuse of such
//: 'ingredient-products' (sometimes called in-out parameters in other
//: languages).
:(scenario return_same_as_ingredient)
% Hide_errors = true;
def main [
1:num <- copy 0
2:num <- test1 1:num # call with different ingredient and product
]
def test1 [
10:num <- next-ingredient
return 10:num/same-as-ingredient:0
]
+error: main: '2:num <- test1 1:num' should write to '1:num' rather than '2:num'
:(scenario return_same_as_ingredient_dummy)
def main [
1:num <- copy 0
_ <- test1 1:num # call with different ingredient and product
]
def test1 [
10:num <- next-ingredient
return 10:num/same-as-ingredient:0
]
$error: 0
:(code)
string to_string(const vector<double>& in) {
if (in.empty()) return "[]";
ostringstream out;
if (SIZE(in) == 1) {
out << no_scientific(in.at(0));
return out.str();
}
out << "[";
for (int i = 0; i < SIZE(in); ++i) {
if (i > 0) out << ", ";
out << no_scientific(in.at(i));
}
out << "]";
return out.str();
}