diff --git a/Makefile.am b/Makefile.am
index 343f900..294115c 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -38,11 +38,11 @@ tocktest$(EXEEXT): $(BUILT_SOURCES) $(tocktest_SOURCES) $(config_sources)
 	@MKDIR_P@ obj
 	ghc $(GHC_OPTS) -o tocktest$(EXEEXT) -main-is TestMain --make TestMain -odir obj -hidir obj
 
-GenTagAST$(EXEEXT): $(GenTagAST_SOURCES) data/AST.hs
+GenTagAST$(EXEEXT): $(GenTagAST_SOURCES)
 	@MKDIR_P@ obj
 	ghc $(GHC_OPTS) -o GenTagAST$(EXEEXT) -main-is GenTagAST --make GenTagAST -odir obj -hidir obj
 
-GenOrdAST$(EXEEXT): $(GenOrdAST_SOURCES) data/AST.hs
+GenOrdAST$(EXEEXT): $(GenOrdAST_SOURCES)
 	@MKDIR_P@ obj
 	ghc $(GHC_OPTS) -o GenOrdAST$(EXEEXT) -main-is GenOrdAST --make GenOrdAST -odir obj -hidir obj
 
@@ -168,8 +168,11 @@ tocktest_SOURCES += frontends/RainTypesTest.hs
 tocktest_SOURCES += frontends/StructureOccamTest.hs
 tocktest_SOURCES += transformations/PassTest.hs
 
-GenTagAST_SOURCES = pregen/GenTagAST.hs
-GenOrdAST_SOURCES = pregen/GenOrdAST.hs
+pregen_sources = data/AST.hs
+pregen_sources += pregen/PregenUtils.hs
+
+GenTagAST_SOURCES = pregen/GenTagAST.hs $(pregen_sources)
+GenOrdAST_SOURCES = pregen/GenOrdAST.hs $(pregen_sources)
 
 #The programs to actually build:	
 bin_PROGRAMS = tock
diff --git a/data/AST.hs b/data/AST.hs
index 2f9ba7a..e0c6e7f 100644
--- a/data/AST.hs
+++ b/data/AST.hs
@@ -58,10 +58,7 @@ instance Show Name where
   show n = show $ nameName n
 
 instance Eq Name where
-  (==) a b = nameName a == nameName b
-
-instance Ord Name where
-  compare a b = compare (nameName a) (nameName b)
+  (==) a b = (nameName a) == (nameName b)
 
 -- | The definition of a name.
 data NameDef = NameDef {
@@ -89,7 +86,7 @@ data Direction =
   | DirOutput      -- ^ The output end.
   | DirUnknown     -- ^ Either direction; either this is a whole channel,
                    -- or its direction is to be figured out later.
-  deriving (Show, Eq, Ord, Typeable, Data)
+  deriving (Show, Eq, Typeable, Data)
 
 -- | Attributes of the type of a channel.
 data ChanAttributes = ChanAttributes {
@@ -103,7 +100,7 @@ data ChanAttributes = ChanAttributes {
 -- reads into something of type Int), and a Rain timer (which reads into something
 -- of type Time).
 data TimerType = OccamTimer | RainTimer
-  deriving (Eq, Show, Ord, Typeable, Data)
+  deriving (Eq, Show, Typeable, Data)
 
 -- | A data or protocol type.
 -- The two concepts aren't unified in occam, but they are here, because it
@@ -180,7 +177,7 @@ data ConversionMode =
   DefaultConversion
   | Round
   | Trunc
-  deriving (Show, Eq, Ord, Typeable, Data)
+  deriving (Show, Eq, Typeable, Data)
 
 -- | Which ends (or both) of an array dimension to check the subscript against.
 -- By default, all subscripts in occam have the CheckBoth mode, but
@@ -192,7 +189,7 @@ data SubscriptCheck =
   | CheckLower
   | CheckUpper
   | CheckBoth
-  deriving (Show, Eq, Ord, Typeable, Data)
+  deriving (Show, Eq, Typeable, Data)
 
 -- | A subscript that can be applied to a variable or an expression.
 data Subscript =
@@ -312,7 +309,7 @@ data MonadicOp =
   | MonadicMinus
   | MonadicBitNot
   | MonadicNot
-  deriving (Show, Eq, Ord, Typeable, Data)
+  deriving (Show, Eq, Typeable, Data)
 
 -- | A dyadic (binary) operator.
 data DyadicOp =
@@ -324,7 +321,7 @@ data DyadicOp =
   | Eq | NotEq | Less | More | LessEq | MoreEq
   | After
   | Concat
-  deriving (Show, Eq, Ord, Typeable, Data)
+  deriving (Show, Eq, Typeable, Data)
 
 -- | An item in an input.
 data InputItem =
@@ -470,7 +467,7 @@ data AbbrevMode =
   | Abbrev
   -- | An abbreviation by value.
   | ValAbbrev
-  deriving (Show, Eq, Ord, Typeable, Data)
+  deriving (Show, Eq, Typeable, Data)
 
 -- | Anything that introduces a new name.
 data Specification =
@@ -516,7 +513,7 @@ data SpecType =
 -- This indicates whether a function is inlined by the compiler.
 data SpecMode =
   PlainSpec | InlineSpec
-  deriving (Show, Eq, Ord, Typeable, Data)
+  deriving (Show, Eq, Typeable, Data)
 
 -- | Formal parameters for @PROC@s and @FUNCTION@s.
 data Formal =
@@ -542,7 +539,7 @@ data ParMode =
   -- 'Processor' instances inside this indicate which processor each parallel
   -- process runs on.
   | PlacedPar
-  deriving (Show, Eq, Ord, Typeable, Data)
+  deriving (Show, Eq, Typeable, Data)
 
 -- | A process.
 data Process =
diff --git a/data/CompState.hs b/data/CompState.hs
index 01c17f1..bb802ca 100644
--- a/data/CompState.hs
+++ b/data/CompState.hs
@@ -33,6 +33,7 @@ import qualified Data.Set as Set
 import qualified AST as A
 import Errors (Die, dieP, ErrorReport, Warn, warnP)
 import Metadata
+import OrdAST ()
 
 -- | Modes that Tock can run in.
 data CompMode = ModeFlowGraph | ModeParse | ModeCompile | ModePostC | ModeFull
diff --git a/pregen/GenOrdAST.hs b/pregen/GenOrdAST.hs
index 53aee84..326ed90 100644
--- a/pregen/GenOrdAST.hs
+++ b/pregen/GenOrdAST.hs
@@ -27,8 +27,9 @@ import Control.Monad.Writer
 import Data.Generics
 import Data.List
 
-import qualified AST as A
 import Metadata
+import PregenUtils
+import Utils
 
 genHeader :: [String]
 genHeader = [
@@ -80,42 +81,9 @@ ordFor' typeName x = process $ map processConstr $ dataTypeConstrs $ dataTypeOf
                       ("AST." ++ showConstr c, x, y, z)
   
 items :: [String]
-items = concat
- [ordFor (u :: A.Actual)
- ,ordFor (u :: A.Alternative)
- ,ordFor (u :: A.ArrayConstr)
- ,ordFor (u :: A.ArrayElem)
- ,ordFor (u :: A.ChanAttributes)
- ,ordFor (u :: A.Choice)
- ,ordFor (u :: A.Dimension)
- ,ordFor (u :: A.Expression)
- ,ordFor (u :: A.ExpressionList)
- ,ordFor (u :: A.Formal)
- ,ordFor (u :: A.InputItem)
- ,ordFor (u :: A.InputMode)
- ,ordFor (u :: A.LiteralRepr)
- ,ordFor (u :: A.OutputItem)
- ,ordFor (u :: A.Option)
- ,ordFor (u :: A.Process)
- ,ordFor (u :: A.Replicator)
- ,ordFor (u :: A.Specification)
- ,ordFor (u :: A.SpecType)
- ,ordFor (u :: A.Structured A.Process)
- ,ordFor (u :: A.Structured A.Choice)
- ,ordFor (u :: A.Structured A.Option)
- ,ordFor (u :: A.Structured A.Alternative)
- ,ordFor (u :: A.Structured A.Variant)
- ,ordFor (u :: A.Structured A.ExpressionList)
- ,ordFor (u :: A.Structured ())
- ,ordFor (u :: A.Subscript)
- ,ordFor (u :: A.Type)
- ,ordFor (u :: A.Variable)
- ,ordFor (u :: A.Variant)
- ]
+items = concat [ordFor w | DataBox w <- astTypes]
  where
    ordFor x = ordFor' (show $ typeOf x) x
- 
-   u = undefined
 
 main :: IO ()
 main = putStr $ unlines $ genHeader ++ items
diff --git a/pregen/GenTagAST.hs b/pregen/GenTagAST.hs
index 3d53f31..b8ff8cd 100644
--- a/pregen/GenTagAST.hs
+++ b/pregen/GenTagAST.hs
@@ -26,7 +26,8 @@ import Data.Char
 import Data.Generics
 import Data.List (intersperse)
 
-import qualified AST as A
+import PregenUtils
+import Utils
 
 genHeader :: [String]
 genHeader = [
@@ -104,39 +105,8 @@ consParamsFor x = map consParamsFor' (dataTypeConstrs $ dataTypeOf x)
         cons = gmapQ (show . typeOf) (fromConstr con :: a)
 
 items :: [String]
-items = concat
-    [ gen (u :: A.Actual)
-    , gen (u :: A.Alternative)
-    , gen (u :: A.ArrayConstr)
-    , gen (u :: A.ArrayElem)
-    , gen (u :: A.Choice)
-    , gen (u :: A.Expression)
-    , gen (u :: A.ExpressionList)
-    , gen (u :: A.Formal)
-    , gen (u :: A.InputItem)
-    , gen (u :: A.InputMode)
-    , gen (u :: A.LiteralRepr)
-    , gen (u :: A.OutputItem)
-    , gen (u :: A.Option)
-    , gen (u :: A.Process)
-    , gen (u :: A.Replicator)
-    , gen (u :: A.Specification)
-    , gen (u :: A.SpecType)
-    , gen (u :: A.Subscript)
-    , gen (u :: A.Type)
-    , gen (u :: A.Variable)
-    , gen (u :: A.Variant)
-    , gen (u :: A.Structured A.Process)
-    , gen (u :: A.Structured A.Option)
-    , gen (u :: A.Structured A.Choice)
-    , gen (u :: A.Structured A.Variant)
-    , gen (u :: A.Structured A.Alternative)
-    , gen (u :: A.Structured A.ExpressionList)
-    , gen (u :: A.Structured ())
-    ]
+items = concat [gen w | DataBox w <- astTypes]
   where
-    u = undefined
-
     gen w
         = case typeRepArgs rep of
             -- A parameterised type (e.g. Structured Process).
diff --git a/pregen/PregenUtils.hs b/pregen/PregenUtils.hs
new file mode 100644
index 0000000..cfb22ce
--- /dev/null
+++ b/pregen/PregenUtils.hs
@@ -0,0 +1,74 @@
+{-
+Tock: a compiler for parallel languages
+Copyright (C) 2008  University of Kent
+
+This program is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by the
+Free Software Foundation, either version 2 of the License, or (at your
+option) any later version.
+
+This program is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program.  If not, see <http://www.gnu.org/licenses/>.
+-}
+
+-- | Utilities for metaprogramming.
+module PregenUtils
+  ( astTypes
+  ) where
+
+import Control.Monad.State
+import Data.Generics
+import Data.List
+import Data.Map (Map)
+import qualified Data.Map as Map
+import System.IO.Unsafe
+
+import qualified AST as A
+import Utils
+
+type TypeMap = Map Int (String, DataBox)
+type TypeMapM = State TypeMap
+
+-- | Given a starting value, find all the types that could possibly be inside
+-- it.
+findTypesIn :: Data t => t -> TypeMap
+findTypesIn start = execState (doType start) Map.empty
+  where
+    doType :: Data t => t -> TypeMapM ()
+    doType x
+        =  do map <- get
+              when (not $ key `Map.member` map) $
+                 do modify $ Map.insert key (reps, DataBox x)
+                    when (isAlgType dtype) $
+                      mapM_ doConstr $ dataTypeConstrs dtype
+      where
+        rep = typeOf x
+        key = unsafePerformIO $ typeRepKey rep
+        reps = show rep
+        dtype = dataTypeOf x
+
+        doConstr :: Constr -> TypeMapM ()
+        doConstr ctr
+            = sequence_ [doType x' | DataBox x' <- args]
+          where
+            args = gmapQ DataBox (asTypeOf (fromConstr ctr) x)
+
+-- | Reduce a 'TypeMap' to only the types in a particular module.
+filterModule :: String -> TypeMap -> TypeMap
+filterModule prefix = Map.filter (((prefix ++ ".") `isPrefixOf`) . fst)
+
+-- | Reduce a 'TypeMap' to a list of 'DataBox'es, sorted by name.
+justBoxes :: TypeMap -> [DataBox]
+justBoxes = map snd . sortBy cmp . Map.elems
+  where
+    cmp (l, _) (r, _) = compare l r
+
+-- | Witnesses for all the types defined in the 'AST' module.
+astTypes :: [DataBox]
+astTypes = justBoxes $ filterModule "AST" $ findTypesIn (undefined :: A.AST)
+