1 //: Arrays contain a variable number of elements of the same type. Their value
  2 //: starts with the length of the array.
  3 //:
  4 //: You can create arrays of containers, but containers can only contain
  5 //: elements of a fixed size, so you can't create containers containing arrays.
  6 //: Create containers containing addresses to arrays instead.
  7 
  8 //: You can create arrays using 'create-array'.
  9 :(scenario create_array)
 10 def main [
 11   # create an array occupying locations 1 (for the size) and 2-4 (for the elements)
 12   1:array:num:3 <- create-array
 13 ]
 14 +run: creating array of size 4
 15 
 16 :(before "End Primitive Recipe Declarations")
 17 CREATE_ARRAY,
 18 :(before "End Primitive Recipe Numbers")
 19 put(Recipe_ordinal, "create-array", CREATE_ARRAY);
 20 :(before "End Primitive Recipe Checks")
 21 case CREATE_ARRAY: {
 22   if (inst.products.empty()) {
 23     raise << maybe(get(Recipe, r).name) << "'create-array' needs one product and no ingredients but got '" << inst.original_string << '\n' << end();
 24     break;
 25   }
 26   reagent/*copy*/ product = inst.products.at(0);
 27   // Update CREATE_ARRAY product in Check
 28   if (!is_mu_array(product)) {
 29     raise << maybe(get(Recipe, r).name) << "'create-array' cannot create non-array '" << product.original_string << "'\n" << end();
 30     break;
 31   }
 32   if (!product.type->right) {
 33     raise << maybe(get(Recipe, r).name) << "create array of what? '" << inst.original_string << "'\n" << end();
 34     break;
 35   }
 36   // 'create-array' will need to check properties rather than types
 37   type_tree* array_length_from_type = product.type->right->right;
 38   if (!array_length_from_type) {
 39     raise << maybe(get(Recipe, r).name) << "create array of what size? '" << inst.original_string << "'\n" << end();
 40     break;
 41   }
 42   if (!product.type->right->right->atom)
 43     array_length_from_type = array_length_from_type->left;
 44   if (!is_integer(array_length_from_type->name)) {
 45     raise << maybe(get(Recipe, r).name) << "'create-array' product should specify size of array after its element type, but got '" << product.type->right->right->name << "'\n" << end();
 46     break;
 47   }
 48   break;
 49 }
 50 :(before "End Primitive Recipe Implementations")
 51 case CREATE_ARRAY: {
 52   reagent/*copy*/ product = current_instruction().products.at(0);
 53   // Update CREATE_ARRAY product in Run
 54   int base_address = product.value;
 55   type_tree* array_length_from_type = product.type->right->right;
 56   if (!product.type->right->right->atom)
 57     array_length_from_type = array_length_from_type->left;
 58   int array_length = to_integer(array_length_from_type->name);
 59   // initialize array length, so that size_of will work
 60   trace(9999, "mem") << "storing " << array_length << " in location " << base_address << end();
 61   put(Memory, base_address, array_length);  // in array elements
 62   int size = size_of(product);  // in locations
 63   trace(9998, "run") << "creating array of size " << size << end();
 64   // initialize array
 65   for (int i = 1;  i <= size_of(product);  ++i) {
 66     put(Memory, base_address+i, 0);
 67   }
 68   // no need to update product
 69   goto finish_instruction;
 70 }
 71 
 72 :(scenario copy_array)
 73 # Arrays can be copied around with a single instruction just like numbers,
 74 # no matter how large they are.
 75 # You don't need to pass the size around, since each array variable stores its
 76 # size in memory at run-time. We'll call a variable with an explicit size a
 77 # 'static' array, and one without a 'dynamic' array since it can contain
 78 # arrays of many different sizes.
 79 def main [
 80   1:array:num:3 <- create-array
 81   2:num <- copy 14
 82   3:num <- copy 15
 83   4:num <- copy 16
 84   5:array:num <- copy 1:array:num:3
 85 ]
 86 +mem: storing 3 in location 5
 87 +mem: storing 14 in location 6
 88 +mem: storing 15 in location 7
 89 +mem: storing 16 in location 8
 90 
 91 :(scenario stash_array)
 92 def main [
 93   1:array:num:3 <- create-array
 94   2:num <- copy 14
 95   3:num <- copy 15
 96   4:num <- copy 16
 97   stash [foo:], 1:array:num:3
 98 ]
 99 +app: foo: 3 14 15 16
100 
101 :(before "End types_coercible Special-cases")
102 if (is_mu_array(from) && is_mu_array(to))
103   return types_strictly_match(array_element(from.type), array_element(to.type));
104 
105 :(before "End size_of(reagent r) Special-cases")
106 if (!r.type->atom && r.type->left->atom && r.type->left->value == get(Type_ordinal, "array")) {
107   if (!r.type->right) {
108     raise << maybe(current_recipe_name()) << "'" << r.original_string << "' is an array of what?\n" << end();
109     return 1;
110   }
111   return /*space for length*/1 + array_length(r)*size_of(array_element(r.type));
112 }
113 
114 :(before "End size_of(type) Non-atom Special-cases")
115 if (type->left->value == get(Type_ordinal, "array")) return static_array_length(type);
116 :(code)
117 int static_array_length(const type_tree* type) {
118   if (!type->atom && type->right && !type->right->atom && type->right->right && !type->right->right->atom && !type->right->right->right  // exactly 3 types
119       && type->right->right->left && type->right->right->left->atom && is_integer(type->right->right->left->name)) {  // third 'type' is a number
120     // get size from type
121     return to_integer(type->right->right->left->name);
122   }
123   cerr << to_string(type) << '\n';
124   assert(false);
125 }
126 
127 //: disable the size mismatch check for arrays since the destination array
128 //: need not be initialized
129 :(before "End size_mismatch(x) Special-cases")
130 if (x.type && !x.type->atom && x.type->left->value == get(Type_ordinal, "array")) return false;
131 
132 //:: arrays inside containers
133 //: arrays are disallowed inside containers unless their length is fixed in
134 //: advance
135 
136 :(scenario container_permits_static_array_element)
137 container foo [
138   x:array:num:3
139 ]
140 $error: 0
141 
142 :(before "End insert_container Special-cases")
143 else if (is_integer(type->name)) {  // sometimes types will contain non-type tags, like numbers for the size of an array
144   type->value = 0;
145 }
146 
147 :(scenario container_disallows_dynamic_array_element)
148 % Hide_errors = true;
149 container foo [
150   x:array:num
151 ]
152 +error: container 'foo' cannot determine size of element 'x'
153 
154 :(before "End Load Container Element Definition")
155 {
156   const type_tree* type = info.elements.back().type;
157   if (type && type->atom && type->name == "array") {
158     raise << "container '" << name << "' doesn't specify type of array elements for '" << info.elements.back().name << "'\n" << end();
159     continue;
160   }
161   if (type && !type->atom && type->left->atom && type->left->name == "array") {
162     if (!type->right) {
163       raise << "container '" << name << "' doesn't specify type of array elements for '" << info.elements.back().name << "'\n" << end();
164       continue;
165     }
166     if (!type->right->right || !is_integer(type->right->right->left->name)) {  // array has no length
167       raise << "container '" << name << "' cannot determine size of element '" << info.elements.back().name << "'\n" << end();
168       continue;
169     }
170   }
171 }
172 
173 //: disable the size mismatch check for 'merge' instructions since containers
174 //: can contain arrays, and since we already do plenty of checking for them
175 :(before "End size_mismatch(x) Special-cases")
176 if (current_call().running_step_index < SIZE(get(Recipe, current_call().running_recipe).steps)
177     && current_instruction().operation == MERGE) {
178   return false;
179 }
180 
181 :(scenario merge_static_array_into_container)
182 container foo [
183   x:num
184   y:array:num:3
185 ]
186 def main [
187   1:array:num:3 <- create-array
188   10:foo <- merge 34, 1:array:num:3
189 ]
190 # no errors
191 
192 :(scenario code_inside_container)
193 % Hide_errors = true;
194 container card [
195   rank:num <- next-ingredient
196 ]
197 def foo [
198   1:card <- merge 3
199   2:num <- get 1:card rank:offset
200 ]
201 # shouldn't die
202 
203 //:: containers inside arrays
204 //: make sure we compute container sizes inside arrays
205 
206 :(before "End compute_container_sizes Non-atom Special-cases")
207 else if (type->left->name == "array")
208   compute_container_sizes(array_element(type), pending_metadata, location_for_error_messages);
209 
210 :(before "End Unit Tests")
211 void test_container_sizes_from_array() {
212   // a container we don't have the size for
213   reagent container("x:point");
214   CHECK(!contains_key(Container_metadata, container.type));
215   // scanning an array of the container precomputes the size of the container
216   reagent r("x:array:point");
217   compute_container_sizes(r, "");
218   CHECK(contains_key(Container_metadata, container.type));
219   CHECK_EQ(get(Container_metadata, container.type).size, 2);
220 }
221 
222 void test_container_sizes_from_address_to_array() {
223   // a container we don't have the size for
224   reagent container("x:point");
225   CHECK(!contains_key(Container_metadata, container.type));
226   // scanning an address to an array of the container precomputes the size of the container
227   reagent r("x:address:array:point");
228   compute_container_sizes(r, "");
229   CHECK(contains_key(Container_metadata, container.type));
230   CHECK_EQ(get(Container_metadata, container.type).size, 2);
231 }
232 
233 void test_container_sizes_from_static_array() {
234   // a container we don't have the size for
235   reagent container("x:point");
236   int old_size = SIZE(Container_metadata);
237   // scanning an address to an array of the container precomputes the size of the container
238   reagent r("x:array:point:10");
239   compute_container_sizes(r, "");
240   CHECK(contains_key(Container_metadata, container.type));
241   CHECK_EQ(get(Container_metadata, container.type).size, 2);
242   // no non-container types precomputed
243   CHECK_EQ(SIZE(Container_metadata)-old_size, 1);
244 }
245 
246 void test_container_sizes_from_address_to_static_array() {
247   // a container we don't have the size for
248   reagent container("x:point");
249   int old_size = SIZE(Container_metadata);
250   // scanning an address to an array of the container precomputes the size of the container
251   reagent r("x:address:array:point:10");
252   compute_container_sizes(r, "");
253   CHECK(contains_key(Container_metadata, container.type));
254   CHECK_EQ(get(Container_metadata, container.type).size, 2);
255   // no non-container types precomputed
256   CHECK_EQ(SIZE(Container_metadata)-old_size, 1);
257 }
258 
259 void test_container_sizes_from_repeated_address_and_array_types() {
260   // a container we don't have the size for
261   reagent container("x:point");
262   int old_size = SIZE(Container_metadata);
263   // scanning repeated address and array types modifying the container precomputes the size of the container
264   reagent r("x:address:array:address:array:point:10");
265   compute_container_sizes(r, "");
266   CHECK(contains_key(Container_metadata, container.type));
267   CHECK_EQ(get(Container_metadata, container.type).size, 2);
268   // no non-container types precomputed
269   CHECK_EQ(SIZE(Container_metadata)-old_size, 1);
270 }
271 
272 //:: To access elements of an array, use 'index'
273 
274 :(scenario index)
275 def main [
276   1:array:num:3 <- create-array
277   2:num <- copy 14
278   3:num <- copy 15
279   4:num <- copy 16
280   5:num <- index 1:array:num:3, 0/index  # the index must be a non-negative whole number
281 ]
282 +mem: storing 14 in location 5
283 
284 :(scenario index_compound_element)
285 def main [
286   {1: (array (address number) 3)} <- create-array
287   2:num <- copy 14
288   3:num <- copy 15
289   4:num <- copy 16
290   5:address:num <- index {1: (array (address number) 3)}, 0
291 ]
292 +mem: storing 14 in location 5
293 
294 :(scenario index_direct_offset)
295 def main [
296   1:array:num:3 <- create-array
297   2:num <- copy 14
298   3:num <- copy 15
299   4:num <- copy 16
300   5:num <- copy 0
301   6:num <- index 1:array:num, 5:num
302 ]
303 +mem: storing 14 in location 6
304 
305 :(before "End Primitive Recipe Declarations")
306 INDEX,
307 :(before "End Primitive Recipe Numbers")
308 put(Recipe_ordinal, "index", INDEX);
309 :(before "End Primitive Recipe Checks")
310 case INDEX: {
311   if (SIZE(inst.ingredients) != 2) {
312     raise << maybe(get(Recipe, r).name) << "'index' expects exactly 2 ingredients in '" << inst.original_string << "'\n" << end();
313     break;
314   }
315   reagent/*copy*/ base = inst.ingredients.at(0);
316   // Update INDEX base in Check
317   if (!is_mu_array(base)) {
318     raise << maybe(get(Recipe, r).name) << "'index' on a non-array '" << base.original_string << "'\n" << end();
319     break;
320   }
321   reagent/*copy*/ index = inst.ingredients.at(1);
322   // Update INDEX index in Check
323   if (!is_mu_number(index)) {
324     raise << maybe(get(Recipe, r).name) << "second ingredient of 'index' should be a number, but got '" << index.original_string << "'\n" << end();
325     break;
326   }
327   if (inst.products.empty()) break;
328   reagent/*copy*/ product = inst.products.at(0);
329   // Update INDEX product in Check
330   reagent/*local*/ element;
331   element.type = copy_array_element(base.type);
332   if (!types_coercible(product, element)) {
333     raise << maybe(get(Recipe, r).name) << "'index' on '" << base.original_string << "' can't be saved in '" << product.original_string << "'; type should be '" << names_to_string_without_quotes(element.type) << "'\n" << end();
334     break;
335   }
336   break;
337 }
338 :(before "End Primitive Recipe Implementations")
339 case INDEX: {
340   reagent/*copy*/ base = current_instruction().ingredients.at(0);
341   // Update INDEX base in Run
342   int base_address = base.value;
343   trace(9998, "run") << "base address is " << base_address << end();
344   if (base_address == 0) {
345     raise << maybe(current_recipe_name()) << "tried to access location 0 in '" << to_original_string(current_instruction()) << "'\n" << end();
346     break;
347   }
348   reagent/*copy*/ index = current_instruction().ingredients.at(1);
349   // Update INDEX index in Run
350   vector<double> index_val(read_memory(index));
351   if (index_val.at(0) < 0 || index_val.at(0) >= get_or_insert(Memory, base_address)) {
352     raise << maybe(current_recipe_name()) << "invalid index " << no_scientific(index_val.at(0)) << " in '" << to_original_string(current_instruction()) << "'\n" << end();
353     break;
354   }
355   reagent/*local*/ element;
356   element.type = copy_array_element(base.type);
357   element.set_value(base_address + /*skip length*/1 + index_val.at(0)*size_of(element.type));
358   trace(9998, "run") << "address to copy is " << element.value << end();
359   trace(9998, "run") << "its type is " << to_string(element.type) << end();
360   // Read element
361   products.push_back(read_memory(element));
362   break;
363 }
364 
365 :(code)
366 type_tree* copy_array_element(const type_tree* type) {
367   return new type_tree(*array_element(type));
368 }
369 
370 type_tree* array_element(const type_tree* type) {
371   assert(type->right);
372   if (type->right->atom) {
373     return type->right;
374   }
375   else if (!type->right->right) {
376     return type->right->left;
377   }
378   // hack: support array:num:3 without requiring extra parens
379   else if (type->right->right->left && type->right->right->left->atom && is_integer(type->right->right->left->name)) {
380     assert(!type->right->right->right);
381     return type->right->left;
382   }
383   return type->right;
384 }
385 
386 int array_length(const reagent& x) {
387   // x should already be canonized.
388   // hack: look for length in type
389   if (!x.type->atom && x.type->right && !x.type->right->atom && x.type->right->right && !x.type->right->right->atom && !x.type->right->right->right  // exactly 3 types
390       && x.type->right->right->left && x.type->right->right->left->atom && is_integer(x.type->right->right->left->name)) {  // third 'type' is a number
391     // get size from type
392     return to_integer(x.type->right->right->left->name);
393   }
394   // this should never happen at transform time
395   return get_or_insert(Memory, x.value);
396 }
397 
398 :(before "End Unit Tests")
399 void test_array_length_compound() {
400   put(Memory, 1, 3);
401   put(Memory, 2, 14);
402   put(Memory, 3, 15);
403   put(Memory, 4, 16);
404   reagent x("1:array:address:num");  // 3 types, but not a static array
405   populate_value(x);
406   CHECK_EQ(array_length(x), 3);
407 }
408 
409 void test_array_length_static() {
410   reagent x("1:array:num:3");
411   CHECK_EQ(array_length(x), 3);
412 }
413 
414 :(scenario index_truncates)
415 def main [
416   1:array:num:3 <- create-array
417   2:num <- copy 14
418   3:num <- copy 15
419   4:num <- copy 16
420   5:num <- index 1:array:num:3, 1.5  # non-whole number
421 ]
422 # fraction is truncated away
423 +mem: storing 15 in location 5
424 
425 :(scenario index_out_of_bounds)
426 % Hide_errors = true;
427 def main [
428   1:array:num:3 <- create-array
429   2:num <- copy 14
430   3:num <- copy 15
431   4:num <- copy 16
432   5:num <- copy 14
433   6:num <- copy 15
434   7:num <- copy 16
435   index 1:array:num:3, 4  # less than size of array in locations, but larger than its length in elements
436 ]
437 +error: main: invalid index 4 in 'index 1:array:num:3, 4'
438 
439 :(scenario index_out_of_bounds_2)
440 % Hide_errors = true;
441 def main [
442   1:array:point:3 <- create-array
443   2:num <- copy 14
444   3:num <- copy 15
445   4:num <- copy 16
446   5:num <- copy 14
447   6:num <- copy 15
448   7:num <- copy 16
449   index 1:array:point, -1
450 ]
451 +error: main: invalid index -1 in 'index 1:array:point, -1'
452 
453 :(scenario index_product_type_mismatch)
454 % Hide_errors = true;
455 def main [
456   1:array:point:3 <- create-array
457   2:num <- copy 14
458   3:num <- copy 15
459   4:num <- copy 16
460   5:num <- copy 14
461   6:num <- copy 15
462   7:num <- copy 16
463   9:num <- index 1:array:point, 0
464 ]
465 +error: main: 'index' on '1:array:point' can't be saved in '9:num'; type should be 'point'
466 
467 //: we might want to call 'index' without saving the results, say in a sandbox
468 
469 :(scenario index_without_product)
470 def main [
471   1:array:num:3 <- create-array
472   2:num <- copy 14
473   3:num <- copy 15
474   4:num <- copy 16
475   index 1:array:num:3, 0
476 ]
477 # just don't die
478 
479 //:: To write to elements of arrays, use 'put'.
480 
481 :(scenario put_index)
482 def main [
483   1:array:num:3 <- create-array
484   2:num <- copy 14
485   3:num <- copy 15
486   4:num <- copy 16
487   1:array:num <- put-index 1:array:num, 1, 34
488 ]
489 +mem: storing 34 in location 3
490 
491 :(before "End Primitive Recipe Declarations")
492 PUT_INDEX,
493 :(before "End Primitive Recipe Numbers")
494 put(Recipe_ordinal, "put-index", PUT_INDEX);
495 :(before "End Primitive Recipe Checks")
496 case PUT_INDEX: {
497   if (SIZE(inst.ingredients) != 3) {
498     raise << maybe(get(Recipe, r).name) << "'put-index' expects exactly 3 ingredients in '" << inst.original_string << "'\n" << end();
499     break;
500   }
501   reagent/*copy*/ base = inst.ingredients.at(0);
502   // Update PUT_INDEX base in Check
503   if (!is_mu_array(base)) {
504     raise << maybe(get(Recipe, r).name) << "'put-index' on a non-array '" << base.original_string << "'\n" << end();
505     break;
506   }
507   reagent/*copy*/ index = inst.ingredients.at(1);
508   // Update PUT_INDEX index in Check
509   if (!is_mu_number(index)) {
510     raise << maybe(get(Recipe, r).name) << "second ingredient of 'put-index' should have type 'number', but got '" << inst.ingredients.at(1).original_string << "'\n" << end();
511     break;
512   }
513   reagent/*copy*/ value = inst.ingredients.at(2);
514   // Update PUT_INDEX value in Check
515   reagent/*local*/ element;
516   element.type = copy_array_element(base.type);
517   if (!types_coercible(element, value)) {
518     raise << maybe(get(Recipe, r).name) << "'put-index " << base.original_string << ", " << inst.ingredients.at(1).original_string << "' should store " << names_to_string_without_quotes(element.type) << " but '" << value.name << "' has type " << names_to_string_without_quotes(value.type) << '\n' << end();
519     break;
520   }
521   if (inst.products.empty()) break;  // no more checks necessary
522   if (inst.products.at(0).name != inst.ingredients.at(0).name) {
523     raise << maybe(get(Recipe, r).name) << "product of 'put-index' must be first ingredient '" << inst.ingredients.at(0).original_string << "', but got '" << inst.products.at(0).original_string << "'\n" << end();
524     break;
525   }
526   // End PUT_INDEX Product Checks
527   break;
528 }
529 :(before "End Primitive Recipe Implementations")
530 case PUT_INDEX: {
531   reagent/*copy*/ base = current_instruction().ingredients.at(0);
532   // Update PUT_INDEX base in Run
533   int base_address = base.value;
534   if (base_address == 0) {
535     raise << maybe(current_recipe_name()) << "tried to access location 0 in '" << to_original_string(current_instruction()) << "'\n" << end();
536     break;
537   }
538   reagent/*copy*/ index = current_instruction().ingredients.at(1);
539   // Update PUT_INDEX index in Run
540   vector<double> index_val(read_memory(index));
541   if (index_val.at(0) < 0 || index_val.at(0) >= get_or_insert(Memory, base_address)) {
542     raise << maybe(current_recipe_name()) << "invalid index " << no_scientific(index_val.at(0)) << " in '" << to_original_string(current_instruction()) << "'\n" << end();
543     break;
544   }
545   int address = base_address + /*skip length*/1 + index_val.at(0)*size_of(array_element(base.type));
546   trace(9998, "run") << "address to copy to is " << address << end();
547   // optimization: directly write the element rather than updating 'product'
548   // and writing the entire array
549   vector<double> value = read_memory(current_instruction().ingredients.at(2));
550   // Write Memory in PUT_INDEX in Run
551   for (int i = 0;  i < SIZE(value);  ++i) {
552     trace(9999, "mem") << "storing " << no_scientific(value.at(i)) << " in location " << address+i << end();
553     put(Memory, address+i, value.at(i));
554   }
555   goto finish_instruction;
556 }
557 
558 :(scenario put_index_out_of_bounds)
559 % Hide_errors = true;
560 def main [
561   1:array:point:3 <- create-array
562   2:num <- copy 14
563   3:num <- copy 15
564   4:num <- copy 16
565   5:num <- copy 14
566   6:num <- copy 15
567   7:num <- copy 16
568   8:point <- merge 34, 35
569   1:array:point <- put-index 1:array:point, 4, 8:point  # '4' is less than size of array in locations, but larger than its length in elements
570 ]
571 +error: main: invalid index 4 in '1:array:point <- put-index 1:array:point, 4, 8:point'
572 
573 :(scenario put_index_out_of_bounds_2)
574 % Hide_errors = true;
575 def main [
576   1:array:point:3 <- create-array
577   2:num <- copy 14
578   3:num <- copy 15
579   4:num <- copy 16
580   5:num <- copy 14
581   6:num <- copy 15
582   7:num <- copy 16
583   8:point <- merge 34, 35
584   1:array:point <- put-index 1:array:point, -1, 8:point
585 ]
586 +error: main: invalid index -1 in '1:array:point <- put-index 1:array:point, -1, 8:point'
587 
588 :(scenario put_index_product_error)
589 % Hide_errors = true;
590 def main [
591   local-scope
592   load-ingredients
593   1:array:num:3 <- create-array
594   4:array:num:3 <- put-index 1:array:num:3, 0, 34
595 ]
596 +error: main: product of 'put-index' must be first ingredient '1:array:num:3', but got '4:array:num:3'
597 
598 //:: compute the length of an array
599 
600 :(scenario array_length)
601 def main [
602   1:array:num:3 <- create-array
603   2:num <- copy 14
604   3:num <- copy 15
605   4:num <- copy 16
606   5:num <- length 1:array:num:3
607 ]
608 +mem: storing 3 in location 5
609 
610 :(before "End Primitive Recipe Declarations")
611 LENGTH,
612 :(before "End Primitive Recipe Numbers")
613 put(Recipe_ordinal, "length", LENGTH);
614 :(before "End Primitive Recipe Checks")
615 case LENGTH: {
616   if (SIZE(inst.ingredients) != 1) {
617     raise << maybe(get(Recipe, r).name) << "'length' expects exactly 2 ingredients in '" << inst.original_string << "'\n" << end();
618     break;
619   }
620   reagent/*copy*/ array = inst.ingredients.at(0);
621   // Update LENGTH array in Check
622   if (!is_mu_array(array)) {
623     raise << "tried to calculate length of non-array '" << array.original_string << "'\n" << end();
624     break;
625   }
626   break;
627 }
628 :(before "End Primitive Recipe Implementations")
629 case LENGTH: {
630   reagent/*copy*/ array = current_instruction().ingredients.at(0);
631   // Update LENGTH array in Run
632   if (array.value == 0) {
633     raise << maybe(current_recipe_name()) << "tried to access location 0 in '" << to_original_string(current_instruction()) << "'\n" << end();
634     break;
635   }
636   products.resize(1);
637   products.at(0).push_back(get_or_insert(Memory, array.value));
638   break;
639 }
640 
641 //: optimization: none of the instructions in this layer use 'ingredients' so
642 //: stop copying potentially huge arrays into it.
643 :(before "End should_copy_ingredients Special-cases")
644 recipe_ordinal r = current_instruction().operation;
645 if (r == CREATE_ARRAY || r == INDEX || r == PUT_INDEX || r == LENGTH)
646   return false;