diff --git a/common/FlowGraph.hs b/common/FlowGraph.hs
index 127688c..30f0d3d 100644
--- a/common/FlowGraph.hs
+++ b/common/FlowGraph.hs
@@ -45,10 +45,12 @@ module FlowGraph (EdgeLabel(..), FNode(..), FlowGraph, GraphLabelFuncs(..), buil
 
 import Control.Monad.Error
 import Control.Monad.State
+import Data.Generics
 import Data.Graph.Inductive
 
 import qualified AST as A
 import Metadata
+import TreeUtil
 import Utils
 
 -- | A node will either have zero links out, one or more Seq links, or one or more Par links.
@@ -219,3 +221,11 @@ buildFlowGraph funcs s
            return (nStart, nEnd)
     buildProcess p = do (liftM mkPair) $ addNode' (findMeta p) labelProcess p
 
+decomp22 :: (Monad m, Data a, Typeable a0, Typeable a1) => (a0 -> a1 -> a) -> (a1 -> m a1) -> (a -> m a)
+decomp22 con f1 = decomp2 con return f1
+
+decomp23 :: (Monad m, Data a, Typeable a0, Typeable a1, Typeable a2) => (a0 -> a1 -> a2 -> a) -> (a1 -> m a1) -> (a -> m a)
+decomp23 con f1 = decomp3 con return f1 return
+
+decomp33 :: (Monad m, Data a, Typeable a0, Typeable a1, Typeable a2) => (a0 -> a1 -> a2 -> a) -> (a2 -> m a2) -> (a -> m a)
+decomp33 con f2 = decomp3 con return return f2
diff --git a/common/TreeUtil.hs b/common/TreeUtil.hs
index 67bb704..6807b36 100644
--- a/common/TreeUtil.hs
+++ b/common/TreeUtil.hs
@@ -24,6 +24,7 @@ module TreeUtil (
   mkPattern, stopCaringPattern, namePattern, nameAndStopCaringPattern, 
   checkTreeForConstr,
   con0, con1, con2, con3, con4, con5, con6, con7
+  , decomp1, decomp2, decomp3
   ) where
 
 import Control.Monad.State
@@ -381,3 +382,24 @@ con7 :: Data a => (a0 -> a1 -> a2 -> a3 -> a4 -> a5 -> a6 -> a) -> Constr
 con7 f = toConstr (f undefined undefined undefined undefined undefined undefined undefined)
 
 
+popFunc :: Monad m => GenericM (StateT [GenericM' m] m)
+popFunc x = do (f:fs) <- get
+               put fs
+               lift ((unGM f) x)
+
+mkM' :: (Monad m, Typeable a) => (a -> m a)-> GenericM' m
+mkM' f = GM {unGM = mkM f}
+
+gmapFuncs :: (Monad m, Data a) => [GenericM' m] -> a -> m a
+gmapFuncs funcs term = evalStateT (gmapM popFunc term) funcs
+
+--TODO check con against the constructor
+decomp1 :: (Monad m, Data a, Typeable a0) => (a0 -> a) -> (a0 -> m a0) -> (a -> m a)
+decomp1 con f0 = gmapFuncs [mkM' f0]
+
+decomp2 :: (Monad m, Data a, Typeable a0, Typeable a1) => (a0 -> a1 -> a) -> (a0 -> m a0) -> (a1 -> m a1) -> (a -> m a)
+decomp2 con f0 f1 = gmapFuncs [mkM' f0, mkM' f1]
+
+decomp3 :: (Monad m, Data a, Typeable a0, Typeable a1, Typeable a2) => (a0 -> a1 -> a2 -> a) -> (a0 -> m a0) -> (a1 -> m a1) -> (a2 -> m a2) -> (a -> m a)
+decomp3 con f0 f1 f2 = gmapFuncs [mkM' f0, mkM' f1, mkM' f2]
+