1069 - rename record/field to container/element

This seems more obvious to laypeople.

I've also come up with a design for sum types: I'm going to call them
exclusive containers. You call 'get' on containers, 'index' on arrays,
and 'maybe-convert' on exclusive containers (as well as tagged types,
but that's even later).

1 files changed, 170 insertions, 0 deletions

diff --git a/cpp/018container b/cpp/018container
new file mode 100644
index 00000000..ef6b0057
--- /dev/null
+++ b/cpp/018container
@@ -0,0 +1,170 @@
+//: Containers contain a fixed number of elements of different types.
+:(before "End Mu Types Initialization")
+//: We'll use this container as a running example, with two integer elements.
+int point = Type_number["point"] = Next_type_number++;
+Type[point].size = 2;
+Type[point].kind = container;
+Type[point].name = "point";
+vector<type_number> i;
+i.push_back(integer);
+Type[point].elements.push_back(i);
+Type[point].elements.push_back(i);
+
+:(scenario copy_multiple_locations)
+# Containers can be copied around with a single instruction just like integers,
+# no matter how large they are.
+recipe main [
+  1:integer <- copy 34:literal
+  2:integer <- copy 35:literal
+  3:point <- copy 1:point
+]
++run: ingredient 0 is 1
++mem: location 1 is 34
++mem: location 2 is 35
++mem: storing 34 in location 3
++mem: storing 35 in location 4
+
+:(before "End Mu Types Initialization")
+// A more complex container, containing another container as one of its
+// elements.
+int point_integer = Type_number["point-integer"] = Next_type_number++;
+Type[point_integer].size = 2;
+Type[point_integer].kind = container;
+Type[point_integer].name = "point-integer";
+vector<type_number> p2;
+p2.push_back(point);
+Type[point_integer].elements.push_back(p2);
+vector<type_number> i2;
+i2.push_back(integer);
+Type[point_integer].elements.push_back(i2);
+
+:(scenario "copy_handles_nested_container_elements")
+recipe main [
+  12:integer <- copy 34:literal
+  13:integer <- copy 35:literal
+  14:integer <- copy 36:literal
+  15:point-integer <- copy 12:point-integer
+]
++mem: storing 36 in location 17
+
+:(before "End size_of(types) Cases")
+type_info t = Type[types[0]];
+if (t.kind == container) {
+  size_t result = 0;
+  for (size_t i = 0; i < t.elements.size(); ++i) {
+    result += size_of(t.elements[i]);
+  }
+  return result;
+}
+
+//: To access elements of a container, use 'get'
+:(scenario "get")
+recipe main [
+  12:integer <- copy 34:literal
+  13:integer <- copy 35:literal
+  15:integer <- get 12:point, 1:offset
+]
++run: instruction main/2
++run: ingredient 0 is 12
++run: ingredient 1 is 1
++run: address to copy is 13
++run: its type is 1
++mem: location 13 is 35
++run: product 0 is 35
++mem: storing 35 in location 15
+
+:(before "End Globals")
+const int GET = 18;
+:(before "End Primitive Recipe Numbers")
+Recipe_number["get"] = GET;
+assert(Next_recipe_number == GET);
+Next_recipe_number++;
+:(before "End Primitive Recipe Implementations")
+case GET: {
+  trace("run") << "ingredient 0 is " << instructions[pc].ingredients[0].name;
+  reagent base = instructions[pc].ingredients[0];
+  int base_address = base.value;
+  int base_type = base.types[0];
+  assert(Type[base_type].kind == container);
+  trace("run") << "ingredient 1 is " << instructions[pc].ingredients[1].name;
+  assert(isa_literal(instructions[pc].ingredients[1]));
+  size_t offset = instructions[pc].ingredients[1].value;
+  int src = base_address;
+  for (size_t i = 0; i < offset; ++i) {
+    src += size_of(Type[base_type].elements[i]);
+  }
+  trace("run") << "address to copy is " << src;
+  assert(Type[base_type].kind == container);
+  assert(Type[base_type].elements.size() > offset);
+  int src_type = Type[base_type].elements[offset][0];
+  trace("run") << "its type is " << src_type;
+  reagent tmp;
+  tmp.set_value(src);
+  tmp.types.push_back(src_type);
+  vector<int> result(read_memory(tmp));
+  trace("run") << "product 0 is " << result[0];
+  write_memory(instructions[pc].products[0], result);
+  break;
+}
+
+//: 'get' requires a literal in ingredient 1. We'll use a synonym called
+//: 'offset'
+:(before "End Mu Types Initialization")
+Type_number["offset"] = 0;
+
+:(scenario "get_handles_nested_container_elements")
+recipe main [
+  12:integer <- copy 34:literal
+  13:integer <- copy 35:literal
+  14:integer <- copy 36:literal
+  15:integer <- get 12:point-integer, 1:offset
+]
++run: instruction main/2
++run: ingredient 0 is 12
++run: ingredient 1 is 1
++run: address to copy is 14
++run: its type is 1
++mem: location 14 is 36
++run: product 0 is 36
++mem: storing 36 in location 15
+
+:(before "End Globals")
+// To write to elements of containers, you need their address.
+const int GET_ADDRESS = 19;
+:(before "End Primitive Recipe Numbers")
+Recipe_number["get-address"] = GET_ADDRESS;
+assert(Next_recipe_number == GET_ADDRESS);
+Next_recipe_number++;
+:(before "End Primitive Recipe Implementations")
+case GET_ADDRESS: {
+  trace("run") << "ingredient 0 is " << instructions[pc].ingredients[0].name;
+  reagent base = instructions[pc].ingredients[0];
+  int base_address = base.value;
+  int base_type = base.types[0];
+  assert(Type[base_type].kind == container);
+  trace("run") << "ingredient 1 is " << instructions[pc].ingredients[1].name;
+  assert(isa_literal(instructions[pc].ingredients[1]));
+  size_t offset = instructions[pc].ingredients[1].value;
+  int src = base_address;
+  for (size_t i = 0; i < offset; ++i) {
+    src += size_of(Type[base_type].elements[i]);
+  }
+  trace("run") << "address to copy is " << src;
+  vector<int> result;
+  result.push_back(src);
+  trace("run") << "product 0 is " << result[0];
+  write_memory(instructions[pc].products[0], result);
+  break;
+}
+
+:(scenario "get_address")
+recipe main [
+  12:integer <- copy 34:literal
+  13:integer <- copy 35:literal
+  15:address:integer <- get-address 12:point, 1:offset
+]
++run: instruction main/2
++run: ingredient 0 is 12
++run: ingredient 1 is 1
++run: address to copy is 13
++mem: storing 13 in location 15