1 //: Advanced notation for the common/easy case where a recipe takes some fixed
  2 //: number of ingredients and yields some fixed number of products.
  3 
  4 :(scenario recipe_with_header)
  5 def main [
  6   1:num/raw <- add2 3, 5
  7 ]
  8 def add2 x:num, y:num -> z:num [
  9   local-scope
 10   load-ingredients
 11   z:num <- add x, y
 12   return z
 13 ]
 14 +mem: storing 8 in location 1
 15 
 16 //: When loading recipes save any header.
 17 
 18 :(before "End recipe Fields")
 19 bool has_header;
 20 vector<reagent> ingredients;
 21 vector<reagent> products;
 22 :(before "End recipe Constructor")
 23 has_header = false;
 24 
 25 :(before "End Recipe Refinements")
 26 if (in.peek() != '[') {
 27   trace("parse") << "recipe has a header; parsing" << end();
 28   load_recipe_header(in, result);
 29 }
 30 
 31 :(code)
 32 void load_recipe_header(istream& in, recipe& result) {
 33   result.has_header = true;
 34   while (has_data(in) && in.peek() != '[' && in.peek() != '\n') {
 35     string s = next_word(in);
 36     if (s.empty()) {
 37       assert(!has_data(in));
 38       raise << "incomplete recipe header at end of file (0)\n" << end();
 39       return;
 40     }
 41     if (s == "<-")
 42       raise << "recipe " << result.name << " should say '->' and not '<-'\n" << end();
 43     if (s == "->") break;
 44     result.ingredients.push_back(reagent(s));
 45     trace("parse") << "header ingredient: " << result.ingredients.back().original_string << end();
 46     skip_whitespace_but_not_newline(in);
 47   }
 48   while (has_data(in) && in.peek() != '[' && in.peek() != '\n') {
 49     string s = next_word(in);
 50     if (s.empty()) {
 51       assert(!has_data(in));
 52       raise << "incomplete recipe header at end of file (1)\n" << end();
 53       return;
 54     }
 55     result.products.push_back(reagent(s));
 56     trace("parse") << "header product: " << result.products.back().original_string << end();
 57     skip_whitespace_but_not_newline(in);
 58   }
 59   // End Load Recipe Header(result)
 60 }
 61 
 62 :(scenario recipe_handles_stray_comma)
 63 def main [
 64   1:num/raw <- add2 3, 5
 65 ]
 66 def add2 x:num, y:num -> z:num, [
 67   local-scope
 68   load-ingredients
 69   z:num <- add x, y
 70   return z
 71 ]
 72 +mem: storing 8 in location 1
 73 
 74 :(scenario recipe_handles_stray_comma_2)
 75 def main [
 76   foo
 77 ]
 78 def foo, [
 79   1:num/raw <- add 2, 2
 80 ]
 81 def bar [
 82   1:num/raw <- add 2, 3
 83 ]
 84 +mem: storing 4 in location 1
 85 
 86 :(scenario recipe_handles_wrong_arrow)
 87 % Hide_errors = true;
 88 def foo a:num <- b:num [
 89 ]
 90 +error: recipe foo should say '->' and not '<-'
 91 
 92 :(scenario recipe_handles_missing_bracket)
 93 % Hide_errors = true;
 94 def main
 95 ]
 96 +error: main: recipe body must begin with '['
 97 
 98 :(scenario recipe_handles_missing_bracket_2)
 99 % Hide_errors = true;
100 def main
101   local-scope
102   {
103   }
104 ]
105 # doesn't overflow line when reading header
106 -parse: header ingredient: local-scope
107 +error: main: recipe body must begin with '['
108 
109 :(scenario recipe_handles_missing_bracket_3)
110 % Hide_errors = true;
111 def main  # comment
112   local-scope
113   {
114   }
115 ]
116 # doesn't overflow line when reading header
117 -parse: header ingredient: local-scope
118 +error: main: recipe body must begin with '['
119 
120 :(after "Begin debug_string(recipe x)")
121 out << "ingredients:\n";
122 for (int i = 0;  i < SIZE(x.ingredients);  ++i)
123   out << "  " << debug_string(x.ingredients.at(i)) << '\n';
124 out << "products:\n";
125 for (int i = 0;  i < SIZE(x.products);  ++i)
126   out << "  " << debug_string(x.products.at(i)) << '\n';
127 
128 //: If a recipe never mentions any ingredients or products, assume it has a header.
129 
130 :(scenario recipe_without_ingredients_or_products_has_header)
131 def test [
132   1:num <- copy 34
133 ]
134 +parse: recipe test has a header
135 
136 :(before "End Recipe Body(result)")
137 if (!result.has_header) {
138   result.has_header = true;
139   for (int i = 0;  i < SIZE(result.steps);  ++i) {
140     const instruction& inst = result.steps.at(i);
141     if ((inst.name == "reply" && !inst.ingredients.empty())
142         || (inst.name == "return" && !inst.ingredients.empty())
143         || inst.name == "next-ingredient"
144         || inst.name == "ingredient"
145         || inst.name == "rewind-ingredients") {
146       result.has_header = false;
147       break;
148     }
149   }
150 }
151 if (result.has_header) {
152   trace("parse") << "recipe " << result.name << " has a header" << end();
153 }
154 
155 //: Support type abbreviations in headers.
156 
157 :(scenario type_abbreviations_in_recipe_headers)
158 def main [
159   local-scope
160   a:text <- foo
161   1:char/raw <- index *a, 0
162 ]
163 def foo -> a:text [  # 'text' is an abbreviation
164   local-scope
165   load-ingredients
166   a <- new [abc]
167 ]
168 +mem: storing 97 in location 1
169 
170 :(before "End Expand Type Abbreviations(caller)")
171 for (long int i = 0;  i < SIZE(caller.ingredients);  ++i)
172   expand_type_abbreviations(caller.ingredients.at(i).type);
173 for (long int i = 0;  i < SIZE(caller.products);  ++i)
174   expand_type_abbreviations(caller.products.at(i).type);
175 
176 //: Rewrite 'load-ingredients' to instructions to create all reagents in the header.
177 
178 :(before "End Rewrite Instruction(curr, recipe result)")
179 if (curr.name == "load-ingredients" || curr.name == "load-inputs") {
180   curr.clear();
181   recipe_ordinal op = get(Recipe_ordinal, "next-ingredient-without-typechecking");
182   for (int i = 0;  i < SIZE(result.ingredients);  ++i) {
183     curr.operation = op;
184     curr.name = "next-ingredient-without-typechecking";
185     curr.products.push_back(result.ingredients.at(i));
186     result.steps.push_back(curr);
187     curr.clear();
188   }
189 }
190 if (curr.name == "next-ingredient-without-typechecking") {
191   raise << maybe(result.name) << "never call 'next-ingredient-without-typechecking' directly\n" << end();
192   curr.clear();
193 }
194 
195 //: internal version of next-ingredient; don't call this directly
196 :(before "End Primitive Recipe Declarations")
197 NEXT_INGREDIENT_WITHOUT_TYPECHECKING,
198 :(before "End Primitive Recipe Numbers")
199 put(Recipe_ordinal, "next-ingredient-without-typechecking", NEXT_INGREDIENT_WITHOUT_TYPECHECKING);
200 :(before "End Primitive Recipe Checks")
201 case NEXT_INGREDIENT_WITHOUT_TYPECHECKING: {
202   break;
203 }
204 :(before "End Primitive Recipe Implementations")
205 case NEXT_INGREDIENT_WITHOUT_TYPECHECKING: {
206   assert(!Current_routine->calls.empty());
207   if (current_call().next_ingredient_to_process < SIZE(current_call().ingredient_atoms)) {
208     products.push_back(
209         current_call().ingredient_atoms.at(current_call().next_ingredient_to_process));
210     assert(SIZE(products) == 1);  products.resize(2);  // push a new vector
211     products.at(1).push_back(1);
212     ++current_call().next_ingredient_to_process;
213   }
214   else {
215     products.resize(2);
216     // pad the first product with sufficient zeros to match its type
217     products.at(0).resize(size_of(current_instruction().products.at(0)));
218     products.at(1).push_back(0);
219   }
220   break;
221 }
222 
223 //: more useful error messages if someone forgets 'load-ingredients'
224 
225 :(scenario load_ingredients_missing_error)
226 % Hide_errors = true;
227 def foo a:num [
228   local-scope
229   b:num <- add a:num, 1
230 ]
231 +error: foo: tried to read ingredient 'a' in 'b:num <- add a:num, 1' but it hasn't been written to yet
232 +error:   did you forget 'load-ingredients'?
233 
234 :(after "use-before-set Error")
235 if (is_present_in_ingredients(caller, ingredient.name))
236   raise << "  did you forget 'load-ingredients'?\n" << end();
237 
238 :(scenario load_ingredients_missing_error_2)
239 % Hide_errors = true;
240 def foo a:num [
241   local-scope
242   b:num <- add a, 1
243 ]
244 +error: foo: missing type for 'a' in 'b:num <- add a, 1'
245 +error:   did you forget 'load-ingredients'?
246 
247 :(after "missing-type Error 1")
248 if (is_present_in_ingredients(get(Recipe, get(Recipe_ordinal, recipe_name)), x.name))
249   raise << "  did you forget 'load-ingredients'?\n" << end();
250 
251 :(code)
252 bool is_present_in_ingredients(const recipe& callee, const string& ingredient_name) {
253   for (int i = 0;  i < SIZE(callee.ingredients);  ++i) {
254     if (callee.ingredients.at(i).name == ingredient_name)
255       return true;
256   }
257   return false;
258 }
259 
260 //:: Check all calls against headers.
261 
262 :(scenario show_clear_error_on_bad_call)
263 % Hide_errors = true;
264 def main [
265   1:num <- foo 34
266 ]
267 def foo x:point -> y:num [
268   local-scope
269   load-ingredients
270   return 35
271 ]
272 +error: main: ingredient 0 has the wrong type at '1:num <- foo 34'
273 
274 :(scenario show_clear_error_on_bad_call_2)
275 % Hide_errors = true;
276 def main [
277   1:point <- foo 34
278 ]
279 def foo x:num -> y:num [
280   local-scope
281   load-ingredients
282   return x
283 ]
284 +error: main: product 0 has the wrong type at '1:point <- foo 34'
285 
286 :(after "Transform.push_back(check_instruction)")
287 Transform.push_back(check_calls_against_header);  // idempotent
288 :(code)
289 void check_calls_against_header(const recipe_ordinal r) {
290   const recipe& caller = get(Recipe, r);
291   trace(9991, "transform") << "--- type-check calls inside recipe " << caller.name << end();
292   for (int i = 0;  i < SIZE(caller.steps);  ++i) {
293     const instruction& inst = caller.steps.at(i);
294     if (is_primitive(inst.operation)) continue;
295     const recipe& callee = get(Recipe, inst.operation);
296     if (!callee.has_header) continue;
297     for (long int i = 0;  i < min(SIZE(inst.ingredients), SIZE(callee.ingredients));  ++i) {
298       // ingredients coerced from call to callee
299       if (!types_coercible(callee.ingredients.at(i), inst.ingredients.at(i))) {
300         raise << maybe(caller.name) << "ingredient " << i << " has the wrong type at '" << to_original_string(inst) << "'\n" << end();
301         raise << "  ['" << to_string(callee.ingredients.at(i).type) << "' vs '" << to_string(inst.ingredients.at(i).type) << "']\n" << end();
302       }
303     }
304     for (long int i = 0;  i < min(SIZE(inst.products), SIZE(callee.products));  ++i) {
305       if (is_dummy(inst.products.at(i))) continue;
306       // products coerced from callee to call
307       if (!types_coercible(inst.products.at(i), callee.products.at(i))) {
308         raise << maybe(caller.name) << "product " << i << " has the wrong type at '" << to_original_string(inst) << "'\n" << end();
309         raise << "  ['" << to_string(inst.products.at(i).type) << "' vs '" << to_string(callee.products.at(i).type) << "']\n" << end();
310       }
311     }
312   }
313 }
314 
315 //:: Check types going in and out of all recipes with headers.
316 
317 :(scenarios transform)
318 :(scenario recipe_headers_are_checked)
319 % Hide_errors = true;
320 def add2 x:num, y:num -> z:num [
321   local-scope
322   load-ingredients
323   z:&:num <- copy 0/unsafe
324   return z
325 ]
326 +error: add2: replied with the wrong type at 'return z'
327 
328 :(before "End Checks")
329 Transform.push_back(check_return_instructions_against_header);  // idempotent
330 
331 :(code)
332 void check_return_instructions_against_header(const recipe_ordinal r) {
333   const recipe& caller_recipe = get(Recipe, r);
334   if (!caller_recipe.has_header) return;
335   trace(9991, "transform") << "--- checking return instructions against header for " << caller_recipe.name << end();
336   for (int i = 0;  i < SIZE(caller_recipe.steps);  ++i) {
337     const instruction& inst = caller_recipe.steps.at(i);
338     if (inst.name != "reply" && inst.name != "return") continue;
339     if (SIZE(caller_recipe.products) != SIZE(inst.ingredients)) {
340       raise << maybe(caller_recipe.name) << "replied with the wrong number of products at '" << to_original_string(inst) << "'\n" << end();
341       continue;
342     }
343     for (int i = 0;  i < SIZE(caller_recipe.products);  ++i) {
344       if (!types_match(caller_recipe.products.at(i), inst.ingredients.at(i)))
345         raise << maybe(caller_recipe.name) << "replied with the wrong type at '" << to_original_string(inst) << "'\n" << end();
346     }
347   }
348 }
349 
350 :(scenario recipe_headers_are_checked_2)
351 % Hide_errors = true;
352 def add2 x:num, y:num [
353   local-scope
354   load-ingredients
355   z:&:num <- copy 0/unsafe
356   return z
357 ]
358 +error: add2: replied with the wrong number of products at 'return z'
359 
360 :(scenario recipe_headers_are_checked_against_pre_transformed_instructions)
361 % Hide_errors = true;
362 def foo -> x:num [
363   local-scope
364   x:num <- copy 0
365   z:bool <- copy false
366   return-if z, z
367 ]
368 +error: foo: replied with the wrong type at 'return-if z, z'
369 
370 :(scenario recipe_headers_check_for_duplicate_names)
371 % Hide_errors = true;
372 def foo x:num, x:num -> z:num [
373   local-scope
374   load-ingredients
375   return z
376 ]
377 +error: foo: 'x' can't repeat in the ingredients
378 
379 :(scenario recipe_headers_check_for_duplicate_names_2)
380 % Hide_errors = true;
381 def foo x:num, x:num [  # no result
382   local-scope
383   load-ingredients
384 ]
385 +error: foo: 'x' can't repeat in the ingredients
386 
387 :(scenario recipe_headers_check_for_missing_types)
388 % Hide_errors = true;
389 def main [
390   foo 0
391 ]
392 def foo a [  # no type for 'a'
393 ]
394 +error: foo: ingredient 'a' has no type
395 
396 :(before "End recipe Fields")
397 map<string, int> ingredient_index;
398 
399 :(after "Begin Instruction Modifying Transforms")
400 Transform.push_back(check_header_ingredients);  // idempotent
401 
402 :(code)
403 void check_header_ingredients(const recipe_ordinal r) {
404   recipe& caller_recipe = get(Recipe, r);
405   caller_recipe.ingredient_index.clear();
406   trace(9991, "transform") << "--- checking return instructions against header for " << caller_recipe.name << end();
407   for (int i = 0;  i < SIZE(caller_recipe.ingredients);  ++i) {
408     if (caller_recipe.ingredients.at(i).type == NULL)
409       raise << maybe(caller_recipe.name) << "ingredient '" << caller_recipe.ingredients.at(i).name << "' has no type\n" << end();
410     if (contains_key(caller_recipe.ingredient_index, caller_recipe.ingredients.at(i).name))
411       raise << maybe(caller_recipe.name) << "'" << caller_recipe.ingredients.at(i).name << "' can't repeat in the ingredients\n" << end();
412     put(caller_recipe.ingredient_index, caller_recipe.ingredients.at(i).name, i);
413   }
414 }
415 
416 //: Deduce types from the header if possible.
417 
418 :(scenarios run)
419 :(scenario deduce_instruction_types_from_recipe_header)
420 def main [
421   1:num/raw <- add2 3, 5
422 ]
423 def add2 x:num, y:num -> z:num [
424   local-scope
425   load-ingredients
426   z <- add x, y  # no type for z
427   return z
428 ]
429 +mem: storing 8 in location 1
430 
431 :(after "Begin Type Modifying Transforms")
432 Transform.push_back(deduce_types_from_header);  // idempotent
433 
434 :(code)
435 void deduce_types_from_header(const recipe_ordinal r) {
436   recipe& caller_recipe = get(Recipe, r);
437   if (caller_recipe.products.empty()) return;
438   trace(9991, "transform") << "--- deduce types from header for " << caller_recipe.name << end();
439   map<string, const type_tree*> header_type;
440   for (int i = 0;  i < SIZE(caller_recipe.ingredients);  ++i) {
441     if (!caller_recipe.ingredients.at(i).type) continue;  // error handled elsewhere
442     put(header_type, caller_recipe.ingredients.at(i).name, caller_recipe.ingredients.at(i).type);
443     trace(9993, "transform") << "type of " << caller_recipe.ingredients.at(i).name << " is " << names_to_string(caller_recipe.ingredients.at(i).type) << end();
444   }
445   for (int i = 0;  i < SIZE(caller_recipe.products);  ++i) {
446     if (!caller_recipe.products.at(i).type) continue;  // error handled elsewhere
447     put(header_type, caller_recipe.products.at(i).name, caller_recipe.products.at(i).type);
448     trace(9993, "transform") << "type of " << caller_recipe.products.at(i).name << " is " << names_to_string(caller_recipe.products.at(i).type) << end();
449   }
450   for (int i = 0;  i < SIZE(caller_recipe.steps);  ++i) {
451     instruction& inst = caller_recipe.steps.at(i);
452     trace(9992, "transform") << "instruction: " << to_string(inst) << end();
453     for (int i = 0;  i < SIZE(inst.ingredients);  ++i) {
454       if (inst.ingredients.at(i).type) continue;
455       if (header_type.find(inst.ingredients.at(i).name) == header_type.end())
456         continue;
457       if (!contains_key(header_type, inst.ingredients.at(i).name)) continue;  // error handled elsewhere
458       inst.ingredients.at(i).type = new type_tree(*get(header_type, inst.ingredients.at(i).name));
459       trace(9993, "transform") << "type of " << inst.ingredients.at(i).name << " is " << names_to_string(inst.ingredients.at(i).type) << end();
460     }
461     for (int i = 0;  i < SIZE(inst.products);  ++i) {
462       trace(9993, "transform") << "  product: " << to_string(inst.products.at(i)) << end();
463       if (inst.products.at(i).type) continue;
464       if (header_type.find(inst.products.at(i).name) == header_type.end())
465         continue;
466       if (!contains_key(header_type, inst.products.at(i).name)) continue;  // error handled elsewhere
467       inst.products.at(i).type = new type_tree(*get(header_type, inst.products.at(i).name));
468       trace(9993, "transform") << "type of " << inst.products.at(i).name << " is " << names_to_string(inst.products.at(i).type) << end();
469     }
470   }
471 }
472 
473 //: One final convenience: no need to say what to return if the information is
474 //: in the header.
475 
476 :(scenario return_based_on_header)
477 def main [
478   1:num/raw <- add2 3, 5
479 ]
480 def add2 x:num, y:num -> z:num [
481   local-scope
482   load-ingredients
483   z <- add x, y
484   return
485 ]
486 +mem: storing 8 in location 1
487 
488 :(after "Transform.push_back(check_header_ingredients)")
489 Transform.push_back(fill_in_return_ingredients);  // idempotent
490 
491 :(code)
492 void fill_in_return_ingredients(const recipe_ordinal r) {
493   recipe& caller_recipe = get(Recipe, r);
494   trace(9991, "transform") << "--- fill in return ingredients from header for recipe " << caller_recipe.name << end();
495   if (!caller_recipe.has_header) return;
496   for (int i = 0;  i < SIZE(caller_recipe.steps);  ++i) {
497     instruction& inst = caller_recipe.steps.at(i);
498     if (inst.name == "reply" || inst.name == "return")
499       add_header_products(inst, caller_recipe);
500   }
501   // fall through return
502   if (!caller_recipe.steps.empty()) {
503     const instruction& final_instruction = caller_recipe.steps.at(SIZE(caller_recipe.steps)-1);
504     if (final_instruction.name == "reply" || final_instruction.name == "return")
505       return;
506   }
507   instruction inst;
508   inst.name = "return";
509   add_header_products(inst, caller_recipe);
510   caller_recipe.steps.push_back(inst);
511 }
512 
513 void add_header_products(instruction& inst, const recipe& caller_recipe) {
514   assert(inst.name == "reply" || inst.name == "return");
515   // collect any products with the same names as ingredients
516   for (int i = 0;  i < SIZE(caller_recipe.products);  ++i) {
517     // if the ingredient is missing, add it from the header
518     if (SIZE(inst.ingredients) == i)
519       inst.ingredients.push_back(caller_recipe.products.at(i));
520     // if it's missing /same_as_ingredient, try to fill it in
521     if (contains_key(caller_recipe.ingredient_index, caller_recipe.products.at(i).name) && !has_property(inst.ingredients.at(i), "same_as_ingredient")) {
522       ostringstream same_as_ingredient;
523       same_as_ingredient << get(caller_recipe.ingredient_index, caller_recipe.products.at(i).name);
524       inst.ingredients.at(i).properties.push_back(pair<string, string_tree*>("same-as-ingredient", new string_tree(same_as_ingredient.str())));
525     }
526   }
527 }
528 
529 :(scenario explicit_return_ignores_header)
530 def main [
531   1:num/raw, 2:num/raw <- add2 3, 5
532 ]
533 def add2 a:num, b:num -> y:num, z:num [
534   local-scope
535   load-ingredients
536   y <- add a, b
537   z <- subtract a, b
538   return a, z
539 ]
540 +mem: storing 3 in location 1
541 +mem: storing -2 in location 2
542 
543 :(scenario return_on_fallthrough_based_on_header)
544 def main [
545   1:num/raw <- add2 3, 5
546 ]
547 def add2 x:num, y:num -> z:num [
548   local-scope
549   load-ingredients
550   z <- add x, y
551 ]
552 +transform: instruction: return {z: "number"}
553 +mem: storing 8 in location 1
554 
555 :(scenario return_on_fallthrough_already_exists)
556 def main [
557   1:num/raw <- add2 3, 5
558 ]
559 def add2 x:num, y:num -> z:num [
560   local-scope
561   load-ingredients
562   z <- add x, y  # no type for z
563   return z
564 ]
565 +transform: instruction: return {z: ()}
566 -transform: instruction: return z:num
567 +mem: storing 8 in location 1
568 
569 :(scenario return_causes_error_in_empty_recipe)
570 % Hide_errors = true;
571 def foo -> x:num [
572 ]
573 +error: foo: tried to read ingredient 'x' in 'return x:num' but it hasn't been written to yet
574 
575 :(scenario return_after_conditional_return_based_on_header)
576 def main [
577   1:num/raw <- add2 3, 5
578 ]
579 def add2 x:num, y:num -> z:num [
580   local-scope
581   load-ingredients
582   z <- add x, y  # no type for z
583   return-if false, 34
584 ]
585 +mem: storing 8 in location 1
586 
587 :(scenario recipe_headers_perform_same_ingredient_check)
588 % Hide_errors = true;
589 def main [
590   1:num <- copy 34
591   2:num <- copy 34
592   3:num <- add2 1:num, 2:num
593 ]
594 def add2 x:num, y:num -> x:num [
595   local-scope
596   load-ingredients
597 ]
598 +error: main: '3:num <- add2 1:num, 2:num' should write to '1:num' rather than '3:num'
599 
600 //: One special-case is recipe 'main'. Make sure it's only ever taking in text
601 //: ingredients, and returning a single number.
602 
603 :(scenario recipe_header_ingredients_constrained_for_main)
604 % Hide_errors = true;
605 def main x:num [
606 ]
607 +error: ingredients of recipe 'main' must all be text (address:array:character)
608 
609 :(scenario recipe_header_products_constrained_for_main)
610 % Hide_errors = true;
611 def main -> x:text [
612 ]
613 +error: recipe 'main' must return at most a single product, a number
614 
615 :(scenario recipe_header_products_constrained_for_main_2)
616 % Hide_errors = true;
617 def main -> x:num, y:num [
618 ]
619 +error: recipe 'main' must return at most a single product, a number
620 
621 :(after "Transform.push_back(expand_type_abbreviations)")
622 Transform.push_back(check_recipe_header_constraints);
623 :(code)
624 void check_recipe_header_constraints(const recipe_ordinal r) {
625   const recipe& caller = get(Recipe, r);
626   if (caller.name != "main") return;
627   trace(9992, "transform") << "check recipe header constraints for recipe " << caller.name << end();
628   if (!caller.has_header) return;
629   reagent/*local*/ expected_ingredient("x:address:array:character");
630   for (int i = 0; i < SIZE(caller.ingredients); ++i) {
631     if (!types_strictly_match(expected_ingredient, caller.ingredients.at(i))) {
632       raise << "ingredients of recipe 'main' must all be text (address:array:character)\n" << end();
633       break;
634     }
635   }
636   int nprod = SIZE(caller.products);
637   reagent/*local*/ expected_product("x:number");
638   if (nprod > 1
639       || (nprod == 1 && !types_strictly_match(expected_product, caller.products.at(0)))) {
640     raise << "recipe 'main' must return at most a single product, a number\n" << end();
641   }
642 }