2576 - distinguish allocated addresses from others

This is the one major refinement on the C programming model I'm planning
to introduce in mu. Instead of Rust's menagerie of pointer types and
static checking, I want to introduce just one new type, and use it to
perform ref-counting at runtime.

So far all we're doing is updating new's interface. The actual
ref-counting implementation is next.

One implication: I might sometimes need duplicate implementations for a
recipe with allocated vs vanilla addresses of the same type. So far it
seems I can get away with just always passing in allocated addresses;
the situations when you want to pass an unallocated address to a recipe
should be few and far between.

1 files changed, 379 insertions, 379 deletions

diff --git a/edit/011-editor-undo.mu b/edit/011-editor-undo.mu
index 4939013e..82362dd9 100644
--- a/edit/011-editor-undo.mu
+++ b/edit/011-editor-undo.mu
@@ -11,13 +11,13 @@ exclusive-container operation [
 container insert-operation [
   before-row:number
   before-column:number
-  before-top-of-screen:address:duplex-list:character
+  before-top-of-screen:address:shared:duplex-list:character
   after-row:number
   after-column:number
-  after-top-of-screen:address:duplex-list:character
+  after-top-of-screen:address:shared:duplex-list:character
   # inserted text is from 'insert-from' until 'insert-until'; list doesn't have to terminate
-  insert-from:address:duplex-list:character
-  insert-until:address:duplex-list:character
+  insert-from:address:shared:duplex-list:character
+  insert-until:address:shared:duplex-list:character
   tag:number  # event causing this operation; might be used to coalesce runs of similar events
     # 0: no coalesce (enter+indent)
     # 1: regular alphanumeric characters
@@ -26,10 +26,10 @@ container insert-operation [
 container move-operation [
   before-row:number
   before-column:number
-  before-top-of-screen:address:duplex-list:character
+  before-top-of-screen:address:shared:duplex-list:character
   after-row:number
   after-column:number
-  after-top-of-screen:address:duplex-list:character
+  after-top-of-screen:address:shared:duplex-list:character
   tag:number  # event causing this operation; might be used to coalesce runs of similar events
     # 0: no coalesce (touch events, etc)
     # 1: left arrow
@@ -41,13 +41,13 @@ container move-operation [
 container delete-operation [
   before-row:number
   before-column:number
-  before-top-of-screen:address:duplex-list:character
+  before-top-of-screen:address:shared:duplex-list:character
   after-row:number
   after-column:number
-  after-top-of-screen:address:duplex-list:character
-  deleted-text:address:duplex-list:character
-  delete-from:address:duplex-list:character
-  delete-until:address:duplex-list:character
+  after-top-of-screen:address:shared:duplex-list:character
+  deleted-text:address:shared:duplex-list:character
+  delete-from:address:shared:duplex-list:character
+  delete-until:address:shared:duplex-list:character
   tag:number  # event causing this operation; might be used to coalesce runs of similar events
     # 0: no coalesce (ctrl-k, ctrl-u)
     # 1: backspace
@@ -56,8 +56,8 @@ container delete-operation [
 
 # every editor accumulates a list of operations to undo/redo
 container editor-data [
-  undo:address:list:address:operation
-  redo:address:list:address:operation
+  undo:address:shared:list:address:shared:operation
+  redo:address:shared:list:address:shared:operation
 ]
 
 # ctrl-z - undo operation
@@ -65,11 +65,11 @@ after <handle-special-character> [
   {
     undo?:boolean <- equal *c, 26/ctrl-z
     break-unless undo?
-    undo:address:address:list:address:operation <- get-address *editor, undo:offset
+    undo:address:address:shared:list:address:shared:operation <- get-address *editor, undo:offset
     break-unless *undo
-    op:address:operation <- first *undo
+    op:address:shared:operation <- first *undo
     *undo <- rest *undo
-    redo:address:address:list:address:operation <- get-address *editor, redo:offset
+    redo:address:address:shared:list:address:shared:operation <- get-address *editor, redo:offset
     *redo <- push op, *redo
     <handle-undo>
     reply screen/same-as-ingredient:0, editor/same-as-ingredient:1, 1/go-render
@@ -81,11 +81,11 @@ after <handle-special-character> [
   {
     redo?:boolean <- equal *c, 25/ctrl-y
     break-unless redo?
-    redo:address:address:list:address:operation <- get-address *editor, redo:offset
+    redo:address:address:shared:list:address:shared:operation <- get-address *editor, redo:offset
     break-unless *redo
-    op:address:operation <- first *redo
+    op:address:shared:operation <- first *redo
     *redo <- rest *redo
-    undo:address:address:list:address:operation <- get-address *editor, undo:offset
+    undo:address:address:shared:list:address:shared:operation <- get-address *editor, undo:offset
     *undo <- push op, *undo
     <handle-redo>
     reply screen/same-as-ingredient:0, editor/same-as-ingredient:1, 1/go-render
@@ -97,19 +97,19 @@ after <handle-special-character> [
 scenario editor-can-undo-typing [
   # create an editor and type a character
   assume-screen 10/width, 5/height
-  1:address:array:character <- new []
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  1:address:shared:array:character <- new []
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   assume-console [
     type [0]
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   # undo
   assume-console [
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   # character should be gone
   screen-should-contain [
@@ -123,7 +123,7 @@ scenario editor-can-undo-typing [
     type [1]
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   screen-should-contain [
     .          .
@@ -135,34 +135,34 @@ scenario editor-can-undo-typing [
 
 # save operation to undo
 after <insert-character-begin> [
-  top-before:address:duplex-list:character <- get *editor, top-of-screen:offset
-  cursor-before:address:duplex-list:character <- copy *before-cursor
+  top-before:address:shared:duplex-list:character <- get *editor, top-of-screen:offset
+  cursor-before:address:shared:duplex-list:character <- copy *before-cursor
 ]
 before <insert-character-end> [
-  top-after:address:duplex-list:character <- get *editor, top-of-screen:offset
-  undo:address:address:list:address:operation <- get-address *editor, undo:offset
+  top-after:address:shared:duplex-list:character <- get *editor, top-of-screen:offset
+  undo:address:address:shared:list:address:shared:operation <- get-address *editor, undo:offset
   {
     # if previous operation was an insert, coalesce this operation with it
     break-unless *undo
-    op:address:operation <- first *undo
-    typing:address:insert-operation <- maybe-convert *op, typing:variant
+    op:address:shared:operation <- first *undo
+    typing:address:shared:insert-operation <- maybe-convert *op, typing:variant
     break-unless typing
     previous-coalesce-tag:number <- get *typing, tag:offset
     break-unless previous-coalesce-tag
-    insert-until:address:address:duplex-list:character <- get-address *typing, insert-until:offset
+    insert-until:address:address:shared:duplex-list:character <- get-address *typing, insert-until:offset
     *insert-until <- next *before-cursor
     after-row:address:number <- get-address *typing, after-row:offset
     *after-row <- copy *cursor-row
     after-column:address:number <- get-address *typing, after-column:offset
     *after-column <- copy *cursor-column
-    after-top:address:address:duplex-list:character <- get-address *typing, after-top-of-screen:offset
+    after-top:address:address:shared:duplex-list:character <- get-address *typing, after-top-of-screen:offset
     *after-top <- get *editor, top-of-screen:offset
     break +done-adding-insert-operation:label
   }
   # if not, create a new operation
-  insert-from:address:duplex-list:character <- next cursor-before
-  insert-to:address:duplex-list:character <- next insert-from
-  op:address:operation <- new operation:type
+  insert-from:address:shared:duplex-list:character <- next cursor-before
+  insert-to:address:shared:duplex-list:character <- next insert-from
+  op:address:shared:operation <- new operation:type
   *op <- merge 0/insert-operation, save-row/before, save-column/before, top-before, *cursor-row/after, *cursor-column/after, top-after, insert-from, insert-to, 1/coalesce
   editor <- add-operation editor, op
   +done-adding-insert-operation
@@ -172,15 +172,15 @@ before <insert-character-end> [
 after <insert-enter-begin> [
   cursor-row-before:number <- copy *cursor-row
   cursor-column-before:number <- copy *cursor-column
-  top-before:address:duplex-list:character <- get *editor, top-of-screen:offset
-  cursor-before:address:duplex-list:character <- copy *before-cursor
+  top-before:address:shared:duplex-list:character <- get *editor, top-of-screen:offset
+  cursor-before:address:shared:duplex-list:character <- copy *before-cursor
 ]
 before <insert-enter-end> [
-  top-after:address:duplex-list:character <- get *editor, top-of-screen:offset
+  top-after:address:shared:duplex-list:character <- get *editor, top-of-screen:offset
   # never coalesce
-  insert-from:address:duplex-list:character <- next cursor-before
-  insert-to:address:duplex-list:character <- next *before-cursor
-  op:address:operation <- new operation:type
+  insert-from:address:shared:duplex-list:character <- next cursor-before
+  insert-to:address:shared:duplex-list:character <- next *before-cursor
+  op:address:shared:operation <- new operation:type
   *op <- merge 0/insert-operation, cursor-row-before, cursor-column-before, top-before, *cursor-row/after, *cursor-column/after, top-after, insert-from, insert-to, 0/never-coalesce
   editor <- add-operation editor, op
 ]
@@ -189,28 +189,28 @@ before <insert-enter-end> [
 # redo stack, because it's now obsolete.
 # Beware: since we're counting cursor moves as operations, this means just
 # moving the cursor can lose work on the undo stack.
-recipe add-operation editor:address:editor-data, op:address:operation -> editor:address:editor-data [
+recipe add-operation editor:address:shared:editor-data, op:address:shared:operation -> editor:address:shared:editor-data [
   local-scope
   load-ingredients
-  undo:address:address:list:address:operation <- get-address *editor, undo:offset
+  undo:address:address:shared:list:address:shared:operation <- get-address *editor, undo:offset
   *undo <- push op *undo
-  redo:address:address:list:address:operation <- get-address *editor, redo:offset
+  redo:address:address:shared:list:address:shared:operation <- get-address *editor, redo:offset
   *redo <- copy 0
   reply editor/same-as-ingredient:0
 ]
 
 after <handle-undo> [
   {
-    typing:address:insert-operation <- maybe-convert *op, typing:variant
+    typing:address:shared:insert-operation <- maybe-convert *op, typing:variant
     break-unless typing
-    start:address:duplex-list:character <- get *typing, insert-from:offset
-    end:address:duplex-list:character <- get *typing, insert-until:offset
+    start:address:shared:duplex-list:character <- get *typing, insert-from:offset
+    end:address:shared:duplex-list:character <- get *typing, insert-until:offset
     # assert cursor-row/cursor-column/top-of-screen match after-row/after-column/after-top-of-screen
     *before-cursor <- prev start
     remove-between *before-cursor, end
     *cursor-row <- get *typing, before-row:offset
     *cursor-column <- get *typing, before-column:offset
-    top:address:address:duplex-list:character <- get-address *editor, top-of-screen:offset
+    top:address:address:shared:duplex-list:character <- get-address *editor, top-of-screen:offset
     *top <- get *typing, before-top-of-screen:offset
   }
 ]
@@ -218,19 +218,19 @@ after <handle-undo> [
 scenario editor-can-undo-typing-multiple [
   # create an editor and type multiple characters
   assume-screen 10/width, 5/height
-  1:address:array:character <- new []
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  1:address:shared:array:character <- new []
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   assume-console [
     type [012]
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   # undo
   assume-console [
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   # all characters must be gone
   screen-should-contain [
@@ -244,14 +244,14 @@ scenario editor-can-undo-typing-multiple [
 scenario editor-can-undo-typing-multiple-2 [
   # create an editor with some text
   assume-screen 10/width, 5/height
-  1:address:array:character <- new [a]
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  1:address:shared:array:character <- new [a]
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   # type some characters
   assume-console [
     type [012]
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   screen-should-contain [
     .          .
     .012a      .
@@ -263,7 +263,7 @@ scenario editor-can-undo-typing-multiple-2 [
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   # back to original text
   screen-should-contain [
@@ -277,7 +277,7 @@ scenario editor-can-undo-typing-multiple-2 [
     type [3]
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   screen-should-contain [
     .          .
@@ -290,15 +290,15 @@ scenario editor-can-undo-typing-multiple-2 [
 scenario editor-can-undo-typing-enter [
   # create an editor with some text
   assume-screen 10/width, 5/height
-  1:address:array:character <- new [  abc]
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  1:address:shared:array:character <- new [  abc]
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   # new line
   assume-console [
     left-click 1, 8
     press enter
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   screen-should-contain [
     .          .
     .  abc     .
@@ -307,8 +307,8 @@ scenario editor-can-undo-typing-enter [
     .          .
   ]
   # line is indented
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   memory-should-contain [
     3 <- 2
     4 <- 2
@@ -318,10 +318,10 @@ scenario editor-can-undo-typing-enter [
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   memory-should-contain [
     3 <- 1
     4 <- 5
@@ -338,7 +338,7 @@ scenario editor-can-undo-typing-enter [
     type [1]
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   screen-should-contain [
     .          .
@@ -353,14 +353,14 @@ scenario editor-can-undo-typing-enter [
 scenario editor-redo-typing [
   # create an editor, type something, undo
   assume-screen 10/width, 5/height
-  1:address:array:character <- new [a]
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  1:address:shared:array:character <- new [a]
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   assume-console [
     type [012]
     press ctrl-z
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   screen-should-contain [
     .          .
     .a         .
@@ -372,7 +372,7 @@ scenario editor-redo-typing [
     press ctrl-y
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   # all characters must be back
   screen-should-contain [
@@ -386,7 +386,7 @@ scenario editor-redo-typing [
     type [3]
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   screen-should-contain [
     .          .
@@ -398,15 +398,15 @@ scenario editor-redo-typing [
 
 after <handle-redo> [
   {
-    typing:address:insert-operation <- maybe-convert *op, typing:variant
+    typing:address:shared:insert-operation <- maybe-convert *op, typing:variant
     break-unless typing
-    insert-from:address:duplex-list:character <- get *typing, insert-from:offset  # ignore insert-to because it's already been spliced away
+    insert-from:address:shared:duplex-list:character <- get *typing, insert-from:offset  # ignore insert-to because it's already been spliced away
     # assert insert-to matches next(*before-cursor)
     insert-range *before-cursor, insert-from
     # assert cursor-row/cursor-column/top-of-screen match after-row/after-column/after-top-of-screen
     *cursor-row <- get *typing, after-row:offset
     *cursor-column <- get *typing, after-column:offset
-    top:address:address:duplex-list:character <- get-address *editor, top-of-screen:offset
+    top:address:address:shared:duplex-list:character <- get-address *editor, top-of-screen:offset
     *top <- get *typing, after-top-of-screen:offset
   }
 ]
@@ -414,14 +414,14 @@ after <handle-redo> [
 scenario editor-redo-typing-empty [
   # create an editor, type something, undo
   assume-screen 10/width, 5/height
-  1:address:array:character <- new []
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  1:address:shared:array:character <- new []
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   assume-console [
     type [012]
     press ctrl-z
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   screen-should-contain [
     .          .
     .          .
@@ -433,7 +433,7 @@ scenario editor-redo-typing-empty [
     press ctrl-y
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   # all characters must be back
   screen-should-contain [
@@ -447,7 +447,7 @@ scenario editor-redo-typing-empty [
     type [3]
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   screen-should-contain [
     .          .
@@ -460,21 +460,21 @@ scenario editor-redo-typing-empty [
 scenario editor-work-clears-redo-stack [
   # create an editor with some text, do some work, undo
   assume-screen 10/width, 5/height
-  1:address:array:character <- new [abc
+  1:address:shared:array:character <- new [abc
 def
 ghi]
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   assume-console [
     type [1]
     press ctrl-z
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   # do some more work
   assume-console [
     type [0]
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   screen-should-contain [
     .          .
     .0abc      .
@@ -487,7 +487,7 @@ ghi]
     press ctrl-y
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   # nothing should happen
   screen-should-contain [
@@ -502,9 +502,9 @@ ghi]
 scenario editor-can-redo-typing-and-enter-and-tab [
   # create an editor
   assume-screen 10/width, 5/height
-  1:address:array:character <- new []
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  1:address:shared:array:character <- new []
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   # insert some text and tabs, hit enter, some more text and tabs
   assume-console [
     press tab
@@ -515,7 +515,7 @@ scenario editor-can-redo-typing-and-enter-and-tab [
     press tab
     type [efg]
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   screen-should-contain [
     .          .
     .  ab  cd  .
@@ -523,8 +523,8 @@ scenario editor-can-redo-typing-and-enter-and-tab [
     .┈┈┈┈┈┈┈┈┈┈.
     .          .
   ]
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   memory-should-contain [
     3 <- 2
     4 <- 7
@@ -534,11 +534,11 @@ scenario editor-can-redo-typing-and-enter-and-tab [
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   # typing in second line deleted, but not indent
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   memory-should-contain [
     3 <- 2
     4 <- 2
@@ -555,11 +555,11 @@ scenario editor-can-redo-typing-and-enter-and-tab [
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   # indent and newline deleted
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   memory-should-contain [
     3 <- 1
     4 <- 8
@@ -575,11 +575,11 @@ scenario editor-can-redo-typing-and-enter-and-tab [
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   # empty screen
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   memory-should-contain [
     3 <- 1
     4 <- 0
@@ -595,11 +595,11 @@ scenario editor-can-redo-typing-and-enter-and-tab [
     press ctrl-y
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   # first line inserted
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   memory-should-contain [
     3 <- 1
     4 <- 8
@@ -615,11 +615,11 @@ scenario editor-can-redo-typing-and-enter-and-tab [
     press ctrl-y
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   # newline and indent inserted
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   memory-should-contain [
     3 <- 2
     4 <- 2
@@ -636,11 +636,11 @@ scenario editor-can-redo-typing-and-enter-and-tab [
     press ctrl-y
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   # indent and newline deleted
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   memory-should-contain [
     3 <- 2
     4 <- 7
@@ -659,24 +659,24 @@ scenario editor-can-redo-typing-and-enter-and-tab [
 scenario editor-can-undo-touch [
   # create an editor with some text
   assume-screen 10/width, 5/height
-  1:address:array:character <- new [abc
+  1:address:shared:array:character <- new [abc
 def
 ghi]
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   # move the cursor
   assume-console [
     left-click 3, 1
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   # undo
   assume-console [
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
-    3:number <- get *2:address:editor-data, cursor-row:offset
-    4:number <- get *2:address:editor-data, cursor-column:offset
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
+    3:number <- get *2:address:shared:editor-data, cursor-row:offset
+    4:number <- get *2:address:shared:editor-data, cursor-column:offset
   ]
   # click undone
   memory-should-contain [
@@ -688,7 +688,7 @@ ghi]
     type [1]
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   screen-should-contain [
     .          .
@@ -702,20 +702,20 @@ ghi]
 after <move-cursor-begin> [
   before-cursor-row:number <- get *editor, cursor-row:offset
   before-cursor-column:number <- get *editor, cursor-column:offset
-  before-top-of-screen:address:duplex-list:character <- get *editor, top-of-screen:offset
+  before-top-of-screen:address:shared:duplex-list:character <- get *editor, top-of-screen:offset
 ]
 before <move-cursor-end> [
   after-cursor-row:number <- get *editor, cursor-row:offset
   after-cursor-column:number <- get *editor, cursor-column:offset
-  after-top-of-screen:address:duplex-list:character <- get *editor, top-of-screen:offset
+  after-top-of-screen:address:shared:duplex-list:character <- get *editor, top-of-screen:offset
   {
     break-unless undo-coalesce-tag
     # if previous operation was also a move, and also had the same coalesce
     # tag, coalesce with it
-    undo:address:address:list:address:operation <- get-address *editor, undo:offset
+    undo:address:address:shared:list:address:shared:operation <- get-address *editor, undo:offset
     break-unless *undo
-    op:address:operation <- first *undo
-    move:address:move-operation <- maybe-convert *op, move:variant
+    op:address:shared:operation <- first *undo
+    move:address:shared:move-operation <- maybe-convert *op, move:variant
     break-unless move
     previous-coalesce-tag:number <- get *move, tag:offset
     coalesce?:boolean <- equal undo-coalesce-tag, previous-coalesce-tag
@@ -724,11 +724,11 @@ before <move-cursor-end> [
     *after-row <- copy after-cursor-row
     after-column:address:number <- get-address *move, after-column:offset
     *after-column <- copy after-cursor-column
-    after-top:address:address:duplex-list:character <- get-address *move, after-top-of-screen:offset
+    after-top:address:address:shared:duplex-list:character <- get-address *move, after-top-of-screen:offset
     *after-top <- get *editor, top-of-screen:offset
     break +done-adding-move-operation:label
   }
-  op:address:operation <- new operation:type
+  op:address:shared:operation <- new operation:type
   *op <- merge 1/move-operation, before-cursor-row, before-cursor-column, before-top-of-screen, after-cursor-row, after-cursor-column, after-top-of-screen, undo-coalesce-tag
   editor <- add-operation editor, op
   +done-adding-move-operation
@@ -736,10 +736,10 @@ before <move-cursor-end> [
 
 after <handle-undo> [
   {
-    move:address:move-operation <- maybe-convert *op, move:variant
+    move:address:shared:move-operation <- maybe-convert *op, move:variant
     break-unless move
     # assert cursor-row/cursor-column/top-of-screen match after-row/after-column/after-top-of-screen
-    top:address:address:duplex-list:character <- get-address *editor, top-of-screen:offset
+    top:address:address:shared:duplex-list:character <- get-address *editor, top-of-screen:offset
     *cursor-row <- get *move, before-row:offset
     *cursor-column <- get *move, before-column:offset
     *top <- get *move, before-top-of-screen:offset
@@ -750,18 +750,18 @@ scenario editor-can-undo-scroll [
   # screen has 1 line for menu + 3 lines
   assume-screen 5/width, 4/height
   # editor contains a wrapped line
-  1:address:array:character <- new [a
+  1:address:shared:array:character <- new [a
 b
 cdefgh]
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 5/right
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 5/right
   # position cursor at end of screen and try to move right
   assume-console [
     left-click 3, 3
     press right-arrow
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   # screen scrolls
   screen-should-contain [
     .     .
@@ -778,9 +778,9 @@ cdefgh]
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
-    3:number <- get *2:address:editor-data, cursor-row:offset
-    4:number <- get *2:address:editor-data, cursor-column:offset
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
+    3:number <- get *2:address:shared:editor-data, cursor-row:offset
+    4:number <- get *2:address:shared:editor-data, cursor-column:offset
   ]
   # cursor moved back
   memory-should-contain [
@@ -799,7 +799,7 @@ cdefgh]
     type [1]
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   screen-should-contain [
     .     .
@@ -812,25 +812,25 @@ cdefgh]
 scenario editor-can-undo-left-arrow [
   # create an editor with some text
   assume-screen 10/width, 5/height
-  1:address:array:character <- new [abc
+  1:address:shared:array:character <- new [abc
 def
 ghi]
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   # move the cursor
   assume-console [
     left-click 3, 1
     press left-arrow
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   # undo
   assume-console [
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
-    3:number <- get *2:address:editor-data, cursor-row:offset
-    4:number <- get *2:address:editor-data, cursor-column:offset
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
+    3:number <- get *2:address:shared:editor-data, cursor-row:offset
+    4:number <- get *2:address:shared:editor-data, cursor-column:offset
   ]
   # cursor moves back
   memory-should-contain [
@@ -842,7 +842,7 @@ ghi]
     type [1]
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   screen-should-contain [
     .          .
@@ -856,19 +856,19 @@ ghi]
 scenario editor-can-undo-up-arrow [
   # create an editor with some text
   assume-screen 10/width, 5/height
-  1:address:array:character <- new [abc
+  1:address:shared:array:character <- new [abc
 def
 ghi]
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   # move the cursor
   assume-console [
     left-click 3, 1
     press up-arrow
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   memory-should-contain [
     3 <- 2
     4 <- 1
@@ -878,9 +878,9 @@ ghi]
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
-    3:number <- get *2:address:editor-data, cursor-row:offset
-    4:number <- get *2:address:editor-data, cursor-column:offset
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
+    3:number <- get *2:address:shared:editor-data, cursor-row:offset
+    4:number <- get *2:address:shared:editor-data, cursor-column:offset
   ]
   # cursor moves back
   memory-should-contain [
@@ -892,7 +892,7 @@ ghi]
     type [1]
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   screen-should-contain [
     .          .
@@ -906,25 +906,25 @@ ghi]
 scenario editor-can-undo-down-arrow [
   # create an editor with some text
   assume-screen 10/width, 5/height
-  1:address:array:character <- new [abc
+  1:address:shared:array:character <- new [abc
 def
 ghi]
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   # move the cursor
   assume-console [
     left-click 2, 1
     press down-arrow
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   # undo
   assume-console [
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
-    3:number <- get *2:address:editor-data, cursor-row:offset
-    4:number <- get *2:address:editor-data, cursor-column:offset
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
+    3:number <- get *2:address:shared:editor-data, cursor-row:offset
+    4:number <- get *2:address:shared:editor-data, cursor-column:offset
   ]
   # cursor moves back
   memory-should-contain [
@@ -936,7 +936,7 @@ ghi]
     type [1]
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   screen-should-contain [
     .          .
@@ -950,27 +950,27 @@ ghi]
 scenario editor-can-undo-ctrl-f [
   # create an editor with multiple pages of text
   assume-screen 10/width, 5/height
-  1:address:array:character <- new [a
+  1:address:shared:array:character <- new [a
 b
 c
 d
 e
 f]
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   # scroll the page
   assume-console [
     press ctrl-f
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   # undo
   assume-console [
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
-    3:number <- get *2:address:editor-data, cursor-row:offset
-    4:number <- get *2:address:editor-data, cursor-column:offset
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
+    3:number <- get *2:address:shared:editor-data, cursor-row:offset
+    4:number <- get *2:address:shared:editor-data, cursor-column:offset
   ]
   # screen should again show page 1
   screen-should-contain [
@@ -985,27 +985,27 @@ f]
 scenario editor-can-undo-page-down [
   # create an editor with multiple pages of text
   assume-screen 10/width, 5/height
-  1:address:array:character <- new [a
+  1:address:shared:array:character <- new [a
 b
 c
 d
 e
 f]
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   # scroll the page
   assume-console [
     press page-down
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   # undo
   assume-console [
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
-    3:number <- get *2:address:editor-data, cursor-row:offset
-    4:number <- get *2:address:editor-data, cursor-column:offset
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
+    3:number <- get *2:address:shared:editor-data, cursor-row:offset
+    4:number <- get *2:address:shared:editor-data, cursor-column:offset
   ]
   # screen should again show page 1
   screen-should-contain [
@@ -1020,28 +1020,28 @@ f]
 scenario editor-can-undo-ctrl-b [
   # create an editor with multiple pages of text
   assume-screen 10/width, 5/height
-  1:address:array:character <- new [a
+  1:address:shared:array:character <- new [a
 b
 c
 d
 e
 f]
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   # scroll the page down and up
   assume-console [
     press page-down
     press ctrl-b
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   # undo
   assume-console [
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
-    3:number <- get *2:address:editor-data, cursor-row:offset
-    4:number <- get *2:address:editor-data, cursor-column:offset
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
+    3:number <- get *2:address:shared:editor-data, cursor-row:offset
+    4:number <- get *2:address:shared:editor-data, cursor-column:offset
   ]
   # screen should again show page 2
   screen-should-contain [
@@ -1056,28 +1056,28 @@ f]
 scenario editor-can-undo-page-up [
   # create an editor with multiple pages of text
   assume-screen 10/width, 5/height
-  1:address:array:character <- new [a
+  1:address:shared:array:character <- new [a
 b
 c
 d
 e
 f]
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   # scroll the page down and up
   assume-console [
     press page-down
     press page-up
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   # undo
   assume-console [
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
-    3:number <- get *2:address:editor-data, cursor-row:offset
-    4:number <- get *2:address:editor-data, cursor-column:offset
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
+    3:number <- get *2:address:shared:editor-data, cursor-row:offset
+    4:number <- get *2:address:shared:editor-data, cursor-column:offset
   ]
   # screen should again show page 2
   screen-should-contain [
@@ -1092,25 +1092,25 @@ f]
 scenario editor-can-undo-ctrl-a [
   # create an editor with some text
   assume-screen 10/width, 5/height
-  1:address:array:character <- new [abc
+  1:address:shared:array:character <- new [abc
 def
 ghi]
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   # move the cursor, then to start of line
   assume-console [
     left-click 2, 1
     press ctrl-a
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   # undo
   assume-console [
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
-    3:number <- get *2:address:editor-data, cursor-row:offset
-    4:number <- get *2:address:editor-data, cursor-column:offset
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
+    3:number <- get *2:address:shared:editor-data, cursor-row:offset
+    4:number <- get *2:address:shared:editor-data, cursor-column:offset
   ]
   # cursor moves back
   memory-should-contain [
@@ -1122,7 +1122,7 @@ ghi]
     type [1]
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   screen-should-contain [
     .          .
@@ -1136,25 +1136,25 @@ ghi]
 scenario editor-can-undo-home [
   # create an editor with some text
   assume-screen 10/width, 5/height
-  1:address:array:character <- new [abc
+  1:address:shared:array:character <- new [abc
 def
 ghi]
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   # move the cursor, then to start of line
   assume-console [
     left-click 2, 1
     press home
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   # undo
   assume-console [
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
-    3:number <- get *2:address:editor-data, cursor-row:offset
-    4:number <- get *2:address:editor-data, cursor-column:offset
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
+    3:number <- get *2:address:shared:editor-data, cursor-row:offset
+    4:number <- get *2:address:shared:editor-data, cursor-column:offset
   ]
   # cursor moves back
   memory-should-contain [
@@ -1166,7 +1166,7 @@ ghi]
     type [1]
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   screen-should-contain [
     .          .
@@ -1180,25 +1180,25 @@ ghi]
 scenario editor-can-undo-ctrl-e [
   # create an editor with some text
   assume-screen 10/width, 5/height
-  1:address:array:character <- new [abc
+  1:address:shared:array:character <- new [abc
 def
 ghi]
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   # move the cursor, then to start of line
   assume-console [
     left-click 2, 1
     press ctrl-e
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   # undo
   assume-console [
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
-    3:number <- get *2:address:editor-data, cursor-row:offset
-    4:number <- get *2:address:editor-data, cursor-column:offset
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
+    3:number <- get *2:address:shared:editor-data, cursor-row:offset
+    4:number <- get *2:address:shared:editor-data, cursor-column:offset
   ]
   # cursor moves back
   memory-should-contain [
@@ -1210,7 +1210,7 @@ ghi]
     type [1]
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   screen-should-contain [
     .          .
@@ -1224,25 +1224,25 @@ ghi]
 scenario editor-can-undo-end [
   # create an editor with some text
   assume-screen 10/width, 5/height
-  1:address:array:character <- new [abc
+  1:address:shared:array:character <- new [abc
 def
 ghi]
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   # move the cursor, then to start of line
   assume-console [
     left-click 2, 1
     press end
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   # undo
   assume-console [
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
-    3:number <- get *2:address:editor-data, cursor-row:offset
-    4:number <- get *2:address:editor-data, cursor-column:offset
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
+    3:number <- get *2:address:shared:editor-data, cursor-row:offset
+    4:number <- get *2:address:shared:editor-data, cursor-column:offset
   ]
   # cursor moves back
   memory-should-contain [
@@ -1254,7 +1254,7 @@ ghi]
     type [1]
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   screen-should-contain [
     .          .
@@ -1268,17 +1268,17 @@ ghi]
 scenario editor-separates-undo-insert-from-undo-cursor-move [
   # create an editor, type some text, move the cursor, type some more text
   assume-screen 10/width, 5/height
-  1:address:array:character <- new []
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  1:address:shared:array:character <- new []
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   assume-console [
     type [abc]
     left-click 1, 1
     type [d]
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   screen-should-contain [
     .          .
     .adbc      .
@@ -1294,9 +1294,9 @@ scenario editor-separates-undo-insert-from-undo-cursor-move [
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
-    3:number <- get *2:address:editor-data, cursor-row:offset
-    4:number <- get *2:address:editor-data, cursor-column:offset
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
+    3:number <- get *2:address:shared:editor-data, cursor-row:offset
+    4:number <- get *2:address:shared:editor-data, cursor-column:offset
   ]
   # last letter typed is deleted
   screen-should-contain [
@@ -1314,9 +1314,9 @@ scenario editor-separates-undo-insert-from-undo-cursor-move [
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
-    3:number <- get *2:address:editor-data, cursor-row:offset
-    4:number <- get *2:address:editor-data, cursor-column:offset
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
+    3:number <- get *2:address:shared:editor-data, cursor-row:offset
+    4:number <- get *2:address:shared:editor-data, cursor-column:offset
   ]
   # no change to screen; cursor moves
   screen-should-contain [
@@ -1334,9 +1334,9 @@ scenario editor-separates-undo-insert-from-undo-cursor-move [
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
-    3:number <- get *2:address:editor-data, cursor-row:offset
-    4:number <- get *2:address:editor-data, cursor-column:offset
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
+    3:number <- get *2:address:shared:editor-data, cursor-row:offset
+    4:number <- get *2:address:shared:editor-data, cursor-column:offset
   ]
   # screen empty
   screen-should-contain [
@@ -1354,9 +1354,9 @@ scenario editor-separates-undo-insert-from-undo-cursor-move [
     press ctrl-y
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
-    3:number <- get *2:address:editor-data, cursor-row:offset
-    4:number <- get *2:address:editor-data, cursor-column:offset
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
+    3:number <- get *2:address:shared:editor-data, cursor-row:offset
+    4:number <- get *2:address:shared:editor-data, cursor-column:offset
   ]
   # first insert
   screen-should-contain [
@@ -1374,9 +1374,9 @@ scenario editor-separates-undo-insert-from-undo-cursor-move [
     press ctrl-y
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
-    3:number <- get *2:address:editor-data, cursor-row:offset
-    4:number <- get *2:address:editor-data, cursor-column:offset
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
+    3:number <- get *2:address:shared:editor-data, cursor-row:offset
+    4:number <- get *2:address:shared:editor-data, cursor-column:offset
   ]
   # cursor moves
   screen-should-contain [
@@ -1394,9 +1394,9 @@ scenario editor-separates-undo-insert-from-undo-cursor-move [
     press ctrl-y
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
-    3:number <- get *2:address:editor-data, cursor-row:offset
-    4:number <- get *2:address:editor-data, cursor-column:offset
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
+    3:number <- get *2:address:shared:editor-data, cursor-row:offset
+    4:number <- get *2:address:shared:editor-data, cursor-column:offset
   ]
   # second insert
   screen-should-contain [
@@ -1414,11 +1414,11 @@ scenario editor-separates-undo-insert-from-undo-cursor-move [
 scenario editor-can-undo-multiple-arrows-in-the-same-direction [
   # create an editor with some text
   assume-screen 10/width, 5/height
-  1:address:array:character <- new [abc
+  1:address:shared:array:character <- new [abc
 def
 ghi]
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   # move the cursor
   assume-console [
     left-click 2, 1
@@ -1426,9 +1426,9 @@ ghi]
     press right-arrow
     press up-arrow
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   memory-should-contain [
     3 <- 1
     4 <- 3
@@ -1438,9 +1438,9 @@ ghi]
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
-    3:number <- get *2:address:editor-data, cursor-row:offset
-    4:number <- get *2:address:editor-data, cursor-column:offset
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
+    3:number <- get *2:address:shared:editor-data, cursor-row:offset
+    4:number <- get *2:address:shared:editor-data, cursor-column:offset
   ]
   # up-arrow is undone
   memory-should-contain [
@@ -1452,9 +1452,9 @@ ghi]
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
-    3:number <- get *2:address:editor-data, cursor-row:offset
-    4:number <- get *2:address:editor-data, cursor-column:offset
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
+    3:number <- get *2:address:shared:editor-data, cursor-row:offset
+    4:number <- get *2:address:shared:editor-data, cursor-column:offset
   ]
   # both right-arrows are undone
   memory-should-contain [
@@ -1468,24 +1468,24 @@ ghi]
 scenario editor-redo-touch [
   # create an editor with some text, click on a character, undo
   assume-screen 10/width, 5/height
-  1:address:array:character <- new [abc
+  1:address:shared:array:character <- new [abc
 def
 ghi]
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   assume-console [
     left-click 3, 1
     press ctrl-z
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   # redo
   assume-console [
     press ctrl-y
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
-    3:number <- get *2:address:editor-data, cursor-row:offset
-    4:number <- get *2:address:editor-data, cursor-column:offset
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
+    3:number <- get *2:address:shared:editor-data, cursor-row:offset
+    4:number <- get *2:address:shared:editor-data, cursor-column:offset
   ]
   # cursor moves to left-click
   memory-should-contain [
@@ -1497,7 +1497,7 @@ ghi]
     type [1]
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   screen-should-contain [
     .          .
@@ -1510,12 +1510,12 @@ ghi]
 
 after <handle-redo> [
   {
-    move:address:move-operation <- maybe-convert *op, move:variant
+    move:address:shared:move-operation <- maybe-convert *op, move:variant
     break-unless move
     # assert cursor-row/cursor-column/top-of-screen match after-row/after-column/after-top-of-screen
     *cursor-row <- get *move, after-row:offset
     *cursor-column <- get *move, after-column:offset
-    top:address:address:duplex-list:character <- get-address *editor, top-of-screen:offset
+    top:address:address:shared:duplex-list:character <- get-address *editor, top-of-screen:offset
     *top <- get *move, after-top-of-screen:offset
   }
 ]
@@ -1525,24 +1525,24 @@ after <handle-redo> [
 scenario editor-can-undo-and-redo-backspace [
   # create an editor
   assume-screen 10/width, 5/height
-  1:address:array:character <- new []
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  1:address:shared:array:character <- new []
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   # insert some text and hit backspace
   assume-console [
     type [abc]
     press backspace
     press backspace
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   screen-should-contain [
     .          .
     .a         .
     .┈┈┈┈┈┈┈┈┈┈.
     .          .
   ]
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   memory-should-contain [
     3 <- 1
     4 <- 1
@@ -1552,10 +1552,10 @@ scenario editor-can-undo-and-redo-backspace [
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   memory-should-contain [
     3 <- 1
     4 <- 3
@@ -1571,10 +1571,10 @@ scenario editor-can-undo-and-redo-backspace [
     press ctrl-y
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   memory-should-contain [
     3 <- 1
     4 <- 1
@@ -1589,38 +1589,38 @@ scenario editor-can-undo-and-redo-backspace [
 
 # save operation to undo
 after <backspace-character-begin> [
-  top-before:address:duplex-list:character <- get *editor, top-of-screen:offset
+  top-before:address:shared:duplex-list:character <- get *editor, top-of-screen:offset
 ]
 before <backspace-character-end> [
   {
     break-unless backspaced-cell  # backspace failed; don't add an undo operation
-    top-after:address:duplex-list:character <- get *editor, top-of-screen:offset
-    undo:address:address:list:address:operation <- get-address *editor, undo:offset
+    top-after:address:shared:duplex-list:character <- get *editor, top-of-screen:offset
+    undo:address:address:shared:list:address:shared:operation <- get-address *editor, undo:offset
     {
       # if previous operation was an insert, coalesce this operation with it
       break-unless *undo
-      op:address:operation <- first *undo
-      deletion:address:delete-operation <- maybe-convert *op, delete:variant
+      op:address:shared:operation <- first *undo
+      deletion:address:shared:delete-operation <- maybe-convert *op, delete:variant
       break-unless deletion
       previous-coalesce-tag:number <- get *deletion, tag:offset
       coalesce?:boolean <- equal previous-coalesce-tag, 1/coalesce-backspace
       break-unless coalesce?
-      delete-from:address:address:duplex-list:character <- get-address *deletion, delete-from:offset
+      delete-from:address:address:shared:duplex-list:character <- get-address *deletion, delete-from:offset
       *delete-from <- copy *before-cursor
-      backspaced-so-far:address:address:duplex-list:character <- get-address *deletion, deleted-text:offset
+      backspaced-so-far:address:address:shared:duplex-list:character <- get-address *deletion, deleted-text:offset
       insert-range backspaced-cell, *backspaced-so-far
       *backspaced-so-far <- copy backspaced-cell
       after-row:address:number <- get-address *deletion, after-row:offset
       *after-row <- copy *cursor-row
       after-column:address:number <- get-address *deletion, after-column:offset
       *after-column <- copy *cursor-column
-      after-top:address:address:duplex-list:character <- get-address *deletion, after-top-of-screen:offset
+      after-top:address:address:shared:duplex-list:character <- get-address *deletion, after-top-of-screen:offset
       *after-top <- get *editor, top-of-screen:offset
       break +done-adding-backspace-operation:label
     }
     # if not, create a new operation
-    op:address:operation <- new operation:type
-    deleted-until:address:duplex-list:character <- next *before-cursor
+    op:address:shared:operation <- new operation:type
+    deleted-until:address:shared:duplex-list:character <- next *before-cursor
     *op <- merge 2/delete-operation, save-row/before, save-column/before, top-before, *cursor-row/after, *cursor-column/after, top-after, backspaced-cell/deleted, *before-cursor/delete-from, deleted-until, 1/coalesce-backspace
     editor <- add-operation editor, op
     +done-adding-backspace-operation
@@ -1629,34 +1629,34 @@ before <backspace-character-end> [
 
 after <handle-undo> [
   {
-    deletion:address:delete-operation <- maybe-convert *op, delete:variant
+    deletion:address:shared:delete-operation <- maybe-convert *op, delete:variant
     break-unless deletion
-    start2:address:address:duplex-list:character <- get-address *editor, data:offset
-    anchor:address:duplex-list:character <- get *deletion, delete-from:offset
+    start2:address:address:shared:duplex-list:character <- get-address *editor, data:offset
+    anchor:address:shared:duplex-list:character <- get *deletion, delete-from:offset
     break-unless anchor
-    deleted:address:duplex-list:character <- get *deletion, deleted-text:offset
-    old-cursor:address:duplex-list:character <- last deleted
+    deleted:address:shared:duplex-list:character <- get *deletion, deleted-text:offset
+    old-cursor:address:shared:duplex-list:character <- last deleted
     insert-range anchor, deleted
     # assert cursor-row/cursor-column/top-of-screen match after-row/after-column/after-top-of-screen
     *before-cursor <- copy old-cursor
     *cursor-row <- get *deletion, before-row:offset
     *cursor-column <- get *deletion, before-column:offset
-    top:address:address:duplex-list:character <- get-address *editor, top-of-screen:offset
+    top:address:address:shared:duplex-list:character <- get-address *editor, top-of-screen:offset
     *top <- get *deletion, before-top-of-screen:offset
   }
 ]
 
 after <handle-redo> [
   {
-    deletion:address:delete-operation <- maybe-convert *op, delete:variant
+    deletion:address:shared:delete-operation <- maybe-convert *op, delete:variant
     break-unless deletion
-    start:address:duplex-list:character <- get *deletion, delete-from:offset
-    end:address:duplex-list:character <- get *deletion, delete-until:offset
+    start:address:shared:duplex-list:character <- get *deletion, delete-from:offset
+    end:address:shared:duplex-list:character <- get *deletion, delete-until:offset
     remove-between start, end
     # assert cursor-row/cursor-column/top-of-screen match after-row/after-column/after-top-of-screen
     *cursor-row <- get *deletion, after-row:offset
     *cursor-column <- get *deletion, after-column:offset
-    top:address:address:duplex-list:character <- get-address *editor, top-of-screen:offset
+    top:address:address:shared:duplex-list:character <- get-address *editor, top-of-screen:offset
     *top <- get *deletion, after-top-of-screen:offset
   }
 ]
@@ -1666,9 +1666,9 @@ after <handle-redo> [
 scenario editor-can-undo-and-redo-delete [
   # create an editor
   assume-screen 10/width, 5/height
-  1:address:array:character <- new []
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  1:address:shared:array:character <- new []
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   # insert some text and hit delete and backspace a few times
   assume-console [
     type [abcdef]
@@ -1678,15 +1678,15 @@ scenario editor-can-undo-and-redo-delete [
     press delete
     press delete
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   screen-should-contain [
     .          .
     .af        .
     .┈┈┈┈┈┈┈┈┈┈.
     .          .
   ]
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   memory-should-contain [
     3 <- 1
     4 <- 1
@@ -1696,10 +1696,10 @@ scenario editor-can-undo-and-redo-delete [
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   memory-should-contain [
     3 <- 1
     4 <- 1
@@ -1715,10 +1715,10 @@ scenario editor-can-undo-and-redo-delete [
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   memory-should-contain [
     3 <- 1
     4 <- 2
@@ -1734,10 +1734,10 @@ scenario editor-can-undo-and-redo-delete [
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   memory-should-contain [
     3 <- 1
     4 <- 2
@@ -1753,11 +1753,11 @@ scenario editor-can-undo-and-redo-delete [
     press ctrl-y
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   # first line inserted
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   memory-should-contain [
     3 <- 1
     4 <- 2
@@ -1773,11 +1773,11 @@ scenario editor-can-undo-and-redo-delete [
     press ctrl-y
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   # first line inserted
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   memory-should-contain [
     3 <- 1
     4 <- 1
@@ -1793,11 +1793,11 @@ scenario editor-can-undo-and-redo-delete [
     press ctrl-y
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   # first line inserted
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   memory-should-contain [
     3 <- 1
     4 <- 1
@@ -1811,37 +1811,37 @@ scenario editor-can-undo-and-redo-delete [
 ]
 
 after <delete-character-begin> [
-  top-before:address:duplex-list:character <- get *editor, top-of-screen:offset
+  top-before:address:shared:duplex-list:character <- get *editor, top-of-screen:offset
 ]
 before <delete-character-end> [
   {
     break-unless deleted-cell  # delete failed; don't add an undo operation
-    top-after:address:duplex-list:character <- get *editor, top-of-screen:offset
-    undo:address:address:list:address:operation <- get-address *editor, undo:offset
+    top-after:address:shared:duplex-list:character <- get *editor, top-of-screen:offset
+    undo:address:address:shared:list:address:shared:operation <- get-address *editor, undo:offset
     {
       # if previous operation was an insert, coalesce this operation with it
       break-unless *undo
-      op:address:operation <- first *undo
-      deletion:address:delete-operation <- maybe-convert *op, delete:variant
+      op:address:shared:operation <- first *undo
+      deletion:address:shared:delete-operation <- maybe-convert *op, delete:variant
       break-unless deletion
       previous-coalesce-tag:number <- get *deletion, tag:offset
       coalesce?:boolean <- equal previous-coalesce-tag, 2/coalesce-delete
       break-unless coalesce?
-      delete-until:address:address:duplex-list:character <- get-address *deletion, delete-until:offset
+      delete-until:address:address:shared:duplex-list:character <- get-address *deletion, delete-until:offset
       *delete-until <- next *before-cursor
-      deleted-so-far:address:address:duplex-list:character <- get-address *deletion, deleted-text:offset
+      deleted-so-far:address:address:shared:duplex-list:character <- get-address *deletion, deleted-text:offset
       *deleted-so-far <- append *deleted-so-far, deleted-cell
       after-row:address:number <- get-address *deletion, after-row:offset
       *after-row <- copy *cursor-row
       after-column:address:number <- get-address *deletion, after-column:offset
       *after-column <- copy *cursor-column
-      after-top:address:address:duplex-list:character <- get-address *deletion, after-top-of-screen:offset
+      after-top:address:address:shared:duplex-list:character <- get-address *deletion, after-top-of-screen:offset
       *after-top <- get *editor, top-of-screen:offset
       break +done-adding-delete-operation:label
     }
     # if not, create a new operation
-    op:address:operation <- new operation:type
-    deleted-until:address:duplex-list:character <- next *before-cursor
+    op:address:shared:operation <- new operation:type
+    deleted-until:address:shared:duplex-list:character <- next *before-cursor
     *op <- merge 2/delete-operation, save-row/before, save-column/before, top-before, *cursor-row/after, *cursor-column/after, top-after, deleted-cell/deleted, *before-cursor/delete-from, deleted-until, 2/coalesce-delete
     editor <- add-operation editor, op
     +done-adding-delete-operation
@@ -1853,16 +1853,16 @@ before <delete-character-end> [
 scenario editor-can-undo-and-redo-ctrl-k [
   # create an editor
   assume-screen 10/width, 5/height
-  1:address:array:character <- new [abc
+  1:address:shared:array:character <- new [abc
 def]
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   # insert some text and hit delete and backspace a few times
   assume-console [
     left-click 1, 1
     press ctrl-k
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   screen-should-contain [
     .          .
     .a         .
@@ -1870,8 +1870,8 @@ def]
     .┈┈┈┈┈┈┈┈┈┈.
     .          .
   ]
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   memory-should-contain [
     3 <- 1
     4 <- 1
@@ -1881,7 +1881,7 @@ def]
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   screen-should-contain [
     .          .
@@ -1890,8 +1890,8 @@ def]
     .┈┈┈┈┈┈┈┈┈┈.
     .          .
   ]
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   memory-should-contain [
     3 <- 1
     4 <- 1
@@ -1901,7 +1901,7 @@ def]
     press ctrl-y
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   # first line inserted
   screen-should-contain [
@@ -1911,8 +1911,8 @@ def]
     .┈┈┈┈┈┈┈┈┈┈.
     .          .
   ]
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   memory-should-contain [
     3 <- 1
     4 <- 1
@@ -1922,7 +1922,7 @@ def]
     type [1]
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   screen-should-contain [
     .          .
@@ -1934,15 +1934,15 @@ def]
 ]
 
 after <delete-to-end-of-line-begin> [
-  top-before:address:duplex-list:character <- get *editor, top-of-screen:offset
+  top-before:address:shared:duplex-list:character <- get *editor, top-of-screen:offset
 ]
 before <delete-to-end-of-line-end> [
   {
     break-unless deleted-cells  # delete failed; don't add an undo operation
-    top-after:address:duplex-list:character <- get *editor, top-of-screen:offset
-    undo:address:address:list:address:operation <- get-address *editor, undo:offset
-    op:address:operation <- new operation:type
-    deleted-until:address:duplex-list:character <- next *before-cursor
+    top-after:address:shared:duplex-list:character <- get *editor, top-of-screen:offset
+    undo:address:address:shared:list:address:shared:operation <- get-address *editor, undo:offset
+    op:address:shared:operation <- new operation:type
+    deleted-until:address:shared:duplex-list:character <- next *before-cursor
     *op <- merge 2/delete-operation, save-row/before, save-column/before, top-before, *cursor-row/after, *cursor-column/after, top-after, deleted-cells/deleted, *before-cursor/delete-from, deleted-until, 0/never-coalesce
     editor <- add-operation editor, op
     +done-adding-delete-operation
@@ -1954,16 +1954,16 @@ before <delete-to-end-of-line-end> [
 scenario editor-can-undo-and-redo-ctrl-u [
   # create an editor
   assume-screen 10/width, 5/height
-  1:address:array:character <- new [abc
+  1:address:shared:array:character <- new [abc
 def]
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   # insert some text and hit delete and backspace a few times
   assume-console [
     left-click 1, 2
     press ctrl-u
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   screen-should-contain [
     .          .
     .c         .
@@ -1971,8 +1971,8 @@ def]
     .┈┈┈┈┈┈┈┈┈┈.
     .          .
   ]
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   memory-should-contain [
     3 <- 1
     4 <- 0
@@ -1982,7 +1982,7 @@ def]
     press ctrl-z
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   screen-should-contain [
     .          .
@@ -1991,8 +1991,8 @@ def]
     .┈┈┈┈┈┈┈┈┈┈.
     .          .
   ]
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   memory-should-contain [
     3 <- 1
     4 <- 2
@@ -2002,7 +2002,7 @@ def]
     press ctrl-y
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   # first line inserted
   screen-should-contain [
@@ -2012,8 +2012,8 @@ def]
     .┈┈┈┈┈┈┈┈┈┈.
     .          .
   ]
-  3:number <- get *2:address:editor-data, cursor-row:offset
-  4:number <- get *2:address:editor-data, cursor-column:offset
+  3:number <- get *2:address:shared:editor-data, cursor-row:offset
+  4:number <- get *2:address:shared:editor-data, cursor-column:offset
   memory-should-contain [
     3 <- 1
     4 <- 0
@@ -2023,7 +2023,7 @@ def]
     type [1]
   ]
   run [
-    editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+    editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   ]
   screen-should-contain [
     .          .
@@ -2035,15 +2035,15 @@ def]
 ]
 
 after <delete-to-start-of-line-begin> [
-  top-before:address:duplex-list:character <- get *editor, top-of-screen:offset
+  top-before:address:shared:duplex-list:character <- get *editor, top-of-screen:offset
 ]
 before <delete-to-start-of-line-end> [
   {
     break-unless deleted-cells  # delete failed; don't add an undo operation
-    top-after:address:duplex-list:character <- get *editor, top-of-screen:offset
-    undo:address:address:list:address:operation <- get-address *editor, undo:offset
-    op:address:operation <- new operation:type
-    deleted-until:address:duplex-list:character <- next *before-cursor
+    top-after:address:shared:duplex-list:character <- get *editor, top-of-screen:offset
+    undo:address:address:shared:list:address:shared:operation <- get-address *editor, undo:offset
+    op:address:shared:operation <- new operation:type
+    deleted-until:address:shared:duplex-list:character <- next *before-cursor
     *op <- merge 2/delete-operation, save-row/before, save-column/before, top-before, *cursor-row/after, *cursor-column/after, top-after, deleted-cells/deleted, *before-cursor/delete-from, deleted-until, 0/never-coalesce
     editor <- add-operation editor, op
     +done-adding-delete-operation
@@ -2053,16 +2053,16 @@ before <delete-to-start-of-line-end> [
 scenario editor-can-undo-and-redo-ctrl-u-2 [
   # create an editor
   assume-screen 10/width, 5/height
-  1:address:array:character <- new []
-  2:address:editor-data <- new-editor 1:address:array:character, screen:address:screen, 0/left, 10/right
-  editor-render screen, 2:address:editor-data
+  1:address:shared:array:character <- new []
+  2:address:shared:editor-data <- new-editor 1:address:shared:array:character, screen:address:shared:screen, 0/left, 10/right
+  editor-render screen, 2:address:shared:editor-data
   # insert some text and hit delete and backspace a few times
   assume-console [
     type [abc]
     press ctrl-u
     press ctrl-z
   ]
-  editor-event-loop screen:address:screen, console:address:console, 2:address:editor-data
+  editor-event-loop screen:address:shared:screen, console:address:shared:console, 2:address:shared:editor-data
   screen-should-contain [
     .          .
     .abc       .