feat(zig): native Arboricx bundle parser and C ABI

src/Research.hs

@@ -12,6 +12,7 @@ import System.Console.CmdArgs    (Data, Typeable)
 
 import qualified Data.ByteString as BS
 import qualified Data.Map        as Map
+import qualified Data.Set        as Set
 import qualified Data.Text       as T
 
 -- Tree Calculus Types
@@ -296,3 +297,41 @@ decodeResult tc =
          || n == 9
          || n == 10
          || n == 13
+
+-- ---------------------------------------------------------------------------
+-- DAG node-table export (for host-language kernel embedding)
+-- ---------------------------------------------------------------------------
+
+-- | Export a term's Merkle DAG as a topologically-sorted node table.
+-- Children appear before parents so all index references are forward.
+-- Returns (root index, list of (tag, [child_indices])).
+exportDag :: T -> (Int, [(String, [Int])])
+exportDag term =
+  let (root, acc, _) = collectDag term [] Set.empty
+      -- acc is in reverse post-order (children first, root last)
+      ordered = reverse acc
+      idxMap = Map.fromList [(h, i) | (i, (h, _)) <- zip [0..] ordered]
+      rootIdx = idxMap Map.! root
+      lines_ = map (formatNode idxMap . snd) ordered
+  in (rootIdx, lines_)
+  where
+    collectDag :: T -> [(MerkleHash, Node)] -> Set.Set MerkleHash -> (MerkleHash, [(MerkleHash, Node)], Set.Set MerkleHash)
+    collectDag Leaf acc seen =
+      let h = nodeHash NLeaf
+      in if Set.member h seen then (h, acc, seen) else (h, (h, NLeaf) : acc, Set.insert h seen)
+    collectDag (Stem t) acc seen =
+      let (ch, acc', seen') = collectDag t acc seen
+          node = NStem ch
+          h = nodeHash node
+      in if Set.member h seen' then (h, acc', seen') else (h, (h, node) : acc', Set.insert h seen')
+    collectDag (Fork l r) acc seen =
+      let (lh, acc', seen') = collectDag l acc seen
+          (rh, acc'', seen'') = collectDag r acc' seen'
+          node = NFork lh rh
+          h = nodeHash node
+      in if Set.member h seen'' then (h, acc'', seen'') else (h, (h, node) : acc'', Set.insert h seen'')
+
+    formatNode :: Map.Map MerkleHash Int -> Node -> (String, [Int])
+    formatNode _ NLeaf = ("leaf", [])
+    formatNode idxMap (NStem ch) = ("stem", [idxMap Map.! ch])
+    formatNode idxMap (NFork l r) = ("fork", [idxMap Map.! l, idxMap Map.! r])