1 files changed, 38 insertions, 0 deletions
diff --git a/compatibility/compatibility.nom b/compatibility/compatibility.nom
new file mode 100644
index 0000000..303c05b
--- /dev/null
+++ b/compatibility/compatibility.nom
@@ -0,0 +1,38 @@
+#!/usr/bin/env nomsu -V1
+use "core"
+use "lib/os.nom"
+
+%UPGRADES <- {}
+
+action [upgrade to %version via %upgrade_fn]
+    %UPGRADES.%version <- %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]+"
+    
+    %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
+        run tree %tree