diff --git a/compatibility/compatibility.nom b/compatibility/compatibility.nom
index 303c05b..1e68f35 100644
--- a/compatibility/compatibility.nom
+++ b/compatibility/compatibility.nom
@@ -1,38 +1,78 @@
-#!/usr/bin/env nomsu -V1
+#!/usr/bin/env nomsu -V2.2.4.3
 use "core"
 use "lib/os.nom"
 
 %UPGRADES <- {}
-
-action [upgrade to %version via %upgrade_fn]
+action [upgrade to %version via %upgrade_fn]:
     %UPGRADES.%version <- %upgrade_fn
 
-parse [upgrade %tree to %version as %body] as
+%ACTION_UPGRADES <- {}
+action [upgrade action %stub to %version via %upgrade_fn]:
+    unless (%ACTION_UPGRADES.%version): %ACTION_UPGRADES.%version <- []
+    %ACTION_UPGRADES.%version.%stub <- %upgrade_fn
+
+parse [upgrade %tree to %version as %body] as (..)
     upgrade to %version via ([%] -> (% with %tree -> %body))
 
-action [%tree upgraded from %start_version to %end_version, %tree upgraded to %end_version from %start_version]
-    local action [%ver as list]
-        (% as number) for % where %ver matches "[0-9]+"
+compile [upgrade action %action to %version as %body] to:
+    %replacements <- {}
+    for %i in 1 to (length of %action):
+        if (%action.%i.type is "Var"):
+            %replacements.(%action.%i.1) <- "\(\%tree as lua id)[\%i]"
+    local action [make tree %t]:
+        when:
+            * (%t is "Var" syntax tree):
+                if (%replacements.(%t.1)):
+                    return %replacements.(%t.1)
+                ..else:
+                    return "\(%t.type)(\(quote "\(%t.source)"), \(quote "\(%t.1) \0\(=lua "string.format('%X', __MANGLE_INDEX)")"))"
+            * (%t is syntax tree):
+                %args <- ((make tree %) for % in %t)
+                add "\(\%tree as lua id).source" to %args at index 1
+                return "\(%t.type)(\(%args joined with ", "))"
+            *else: return (quote "\%t")
+    return (..)
+        Lua ".."
+            A_upgrade_action_1_to_2_via_3(\(quote %action.stub), \(%version as lua expr), function(\(\%tree as lua id))
+                __MANGLE_INDEX = (__MANGLE_INDEX or 0) + 1
+                return \(make tree %body)
+            end)
+
+action [..]
+    %tree upgraded from %start_version to %end_version
+    %tree upgraded to %end_version from %start_version
+..:
+    local action [%ver as list] ((% as number) for % where %ver matches "[0-9]+")
+    %versions <- {}
+    for %v = % in %UPGRADES: %versions.%v <- (yes)
+    for %v = % in %ACTION_UPGRADES: %versions.%v <- (yes)
+    %versions <- ((keys in %versions) sorted by % -> (% as list))
+    for %ver in %versions:
+        if ((%ver as list) <= (%start_version as list)): do next %ver
+        if ((%ver as list) > (%end_version as list)): stop %ver
+        if %ACTION_UPGRADES.%ver:
+            %tree <- (..)
+                %tree with % -> (..)
+                    if ((% is "Action" syntax tree) and %ACTION_UPGRADES.%ver.(%.stub)):
+                        return (call %ACTION_UPGRADES.%ver.(%.stub) with [%])
+        if %UPGRADES.%ver:
+            %tree <- (call %UPGRADES.%ver with [%tree])
     
-    %versions <-: (keys in %UPGRADES) sorted by % -> (% as list)
-    for %ver in %versions
-        if: (%ver as list) <= (%start_version as list)
-            do next %ver
-        if: (%ver as list) > (%end_version as list)
-            stop %ver
-        %tree <- (call %UPGRADES.%ver with [%tree])
     return %tree
 
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-parse [%tree upgraded from %start_version] as: %tree upgraded from %start_version to (Nomsu version)
-parse [%tree upgraded to %end_version] as: %tree upgraded from %tree.version to %end_version
-parse [%tree upgraded] as: %tree upgraded from %tree.version to (Nomsu version)
 
-action [use %path from version %version]
-    for file %filename in %path
-        if (=lua "LOADED[\%filename]")
-            do next %filename
-        %file <-: read file %filename
-        %tree <-: parse %file from %filename
-        %tree <-: upgrade %tree from %version
+parse [%tree upgraded from %start_version] as (..)
+    %tree upgraded from %start_version to (Nomsu version)
+
+parse [%tree upgraded to %end_version] as (..)
+    %tree upgraded from %tree.version to %end_version
+
+parse [%tree upgraded] as (%tree upgraded from %tree.version to (Nomsu version))
+action [use %path from version %version] (..)
+    for file %filename in %path:
+        if (=lua "LOADED[\%filename]"): do next %filename
+        %file <- (read file %filename)
+        %tree <- (parse %file from %filename)
+        %tree <- (upgrade %tree from %version)
         run tree %tree
diff --git a/core/collections.nom b/core/collections.nom
index 100781b..d99ae49 100644
--- a/core/collections.nom
+++ b/core/collections.nom
@@ -62,6 +62,9 @@ compile [..]
     to %list append %item
 ..to (Lua "table.insert(\(%list as lua expr), \(%item as lua expr))")
 
+compile [add %item to %list at index %i] to (..)
+    Lua "table.insert(\(%list as lua expr), \(%i as lua expr), \(%item as lua expr))"
+
 compile [pop from %list, remove last from %list] to (..)
     Lua value "table.remove(\(%list as lua expr))"
 
diff --git a/core/metaprogramming.nom b/core/metaprogramming.nom
index f78ab50..c81eb74 100644
--- a/core/metaprogramming.nom
+++ b/core/metaprogramming.nom
@@ -3,7 +3,7 @@
     This File contains actions for making actions and compile-time actions and some helper
     functions to make that easier.
 
-lua> "NOMSU_CORE_VERSION = 2"
+lua> "NOMSU_CORE_VERSION = 3"
 lua> ".."
     nomsu.COMPILE_ACTIONS["% -> %"] = function(nomsu, tree, \%args, \%body)
         local lua = LuaCode.Value(tree.source, "function(")