diff --git a/GraphRewriting/Graph/Write.hs b/GraphRewriting/Graph/Write.hs
--- a/GraphRewriting/Graph/Write.hs
+++ b/GraphRewriting/Graph/Write.hs
@@ -13,6 +13,7 @@
 import GraphRewriting.Graph.Read
 import qualified GraphRewriting.Graph.Write.Unsafe as Unsafe
 import Control.Monad
+import Data.Maybe (catMaybes)
 import Data.View
 import Data.List
 import qualified Data.IntMap as Map
@@ -75,11 +76,17 @@
 	es ← liftM concat $ mapM disconnectPorts =<< attachedNodes e
 	modifyEdgeMap $ Map.delete (eKey e)
 	return es
-	where disconnectPorts n = do
-		ps ← inspectNode n
-		es ← mapM (\p → if p ≡ e then newEdge else return p) ps
-		updateNode n es
-		return es
+	where
+	disconnectPorts n = do
+		ports ← inspectNode n
+		(freshEdges, ports') ← liftM unzip $ mapM substPort ports
+		updateNode n ports'
+		return $ catMaybes freshEdges
+	substPort p = if p ≡ e
+		then do
+			p' ← newEdge
+			return (Just p', p')
+		else return (Nothing, p)
 
 -- | Reconnects the ports connected to the second edge to the first one. Then the second edge is deleted.
 mergeEdges ∷ View [Port] n ⇒ Edge → Edge → Rewrite n ()
diff --git a/GraphRewriting/Graph/Write/Unsafe.hs b/GraphRewriting/Graph/Write/Unsafe.hs
--- a/GraphRewriting/Graph/Write/Unsafe.hs
+++ b/GraphRewriting/Graph/Write/Unsafe.hs
@@ -15,6 +15,8 @@
 import qualified Data.IntSet as Set
 
 
+-- TODO: For the major version change Adjust parameter orders to the ones used in GraphRewriting.Graph.Write
+
 modifyNode ∷ Node → (n → n) → Rewrite n ()
 modifyNode n@(Node i) f = modifyNodeMap . Map.insert i . f =<< readNode n
 
diff --git a/GraphRewriting/Rule.hs b/GraphRewriting/Rule.hs
--- a/GraphRewriting/Rule.hs
+++ b/GraphRewriting/Rule.hs
@@ -19,6 +19,12 @@
 -- | A rewriting rule is defined as a 'Pattern' that returns a 'Rewrite'
 type Rule n = Pattern n (Rewrite n ())
 
+-- | Apply rule at an arbitrary position if applicable
+apply ∷ Rule n → Rewrite n ()
+apply r = do
+	contractions ← liftM (evalPattern r) ask
+	when (not $ null contractions) (head contractions >> return ())
+
 -- rule construction ---------------------------------------------------------
 
 -- | primitive rule construction with the matched nodes of the left hand side as a parameter
@@ -29,15 +35,13 @@
 
 -- | constructs a rule that deletes all of the matched nodes from the graph
 erase ∷ View [Port] n ⇒ Rule n
-erase = liftM (mapM_ deleteNode . nub) history
+erase = rewrite $ mapM_ deleteNode . nub
 
 -- | Constructs a rule from a list of rewirings. Each rewiring specifies a list of hyperedges that are to be merged into a single hyperedge. All matched nodes of the left-hand side are removed.
 rewire ∷ View [Port] n ⇒ [[Edge]] → Rule n
-rewire ess = do
-	hist ← history
-	return $ do
-		mapM_ mergeEs $ joinEdges ess
-		mapM_ deleteNode $ nub hist
+rewire ess = rewrite $ \hist → do
+	mapM_ mergeEs $ joinEdges ess
+	mapM_ deleteNode $ nub hist
 
 data RHS v = Node v | Wire Edge Edge | Merge [Edge]
 
@@ -45,14 +49,14 @@
 replace ∷ (View [Port] n, View v n) ⇒ Int → ([Edge] → [RHS v]) → Rule n
 replace n rhs = do
 	let vs = fst $ partition (replicate n $ Edge 0)
-	hist ← history
-	when (null hist ∧ not (null vs)) (fail "need at least one matching node to clone new nodes from")
+	lhsNodes ← liftM nub history
+	when (null lhsNodes ∧ not (null vs)) (fail "need at least one matching node to clone new nodes from")
 	return $ do
 		es ← replicateM n newEdge
 		let (vs,ess) = partition es
-		zipWithM_ copyNode (cycle hist) vs
+		zipWithM_ copyNode (cycle lhsNodes) vs
 		mapM_ mergeEs $ joinEdges ess
-		mapM_ deleteNode $ nub hist
+		mapM_ deleteNode lhsNodes
 	where partition es = partitionEithers $ map splitRHS (rhs es) where
 		splitRHS (Node v) = Left v
 		splitRHS (Wire e1 e2) = Right [e1,e2]
@@ -91,9 +95,3 @@
 everywhere r = do
 	ms ← amnesia $ matches r
 	exhaustive $ restrictOverlap (\hist future → future ∈ ms) r
-
--- | Apply rule at an arbitrary position if applicable
-apply ∷ Rule n → Rewrite n ()
-apply r = do
-	contractions ← liftM (evalPattern r) ask
-	when (not $ null contractions) (head contractions >> return ())
diff --git a/graph-rewriting.cabal b/graph-rewriting.cabal
--- a/graph-rewriting.cabal
+++ b/graph-rewriting.cabal
@@ -1,5 +1,5 @@
 Name:           graph-rewriting
-Version:        0.5.1
+Version:        0.5.2
 Copyright:      (c) 2010, Jan Rochel
 License:        BSD3
 License-File:   LICENSE