diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,9 @@
+0.6.0.0
+---
+* Split Datatype/Constructor/Field more cleanly.
+* Add support for Enums with no fields.
+* Add a dynamic representation for dynamic updating.
+
 0.5.1.0
 ---
 * Add tuple instances
diff --git a/generic-accessors.cabal b/generic-accessors.cabal
--- a/generic-accessors.cabal
+++ b/generic-accessors.cabal
@@ -1,5 +1,5 @@
 name:                generic-accessors
-version:             0.5.1.0
+version:             0.6.0.0
 synopsis:            stringly-named getters for generic data
 license:             BSD3
 license-file:        LICENSE
@@ -25,11 +25,16 @@
 library
   hs-source-dirs:    src
   default-language:  Haskell2010
-  exposed-modules:   Accessors
+  exposed-modules:   Accessors,
+                     Accessors.Dynamic
+  other-modules:     Accessors.Accessors,
+                     Accessors.Instances
   build-depends:     base >= 4.6.0.0 && < 5
                      , linear
                      , spatial-math >= 0.2.0
                      , lens
+                     , cereal
+                     , binary
 
   ghc-options:      -O2 -Wall
   ghc-prof-options: -O2 -Wall -prof -fprof-auto -fprof-cafs -rtsopts
diff --git a/src/Accessors.hs b/src/Accessors.hs
--- a/src/Accessors.hs
+++ b/src/Accessors.hs
@@ -1,17 +1,15 @@
 {-# OPTIONS_GHC -Wall #-}
-{-# LANGUAGE ScopedTypeVariables #-}
-{-# LANGUAGE DefaultSignatures #-}
-{-# LANGUAGE TypeOperators #-}
-{-# LANGUAGE RankNTypes #-}
-{-# LANGUAGE FlexibleContexts #-}
-{-# LANGUAGE FlexibleInstances #-}
 
 module Accessors
        ( Lookup(..)
-       , AccessorTree(..)
-       , Field(..)
+       , AccessorTree
+       , GAData(..)
+       , GAConstructor(..)
+       , GASimpleEnum(..)
+       , GAField(..)
+       , GATip(..)
        , accessors
-       , describeField
+       , describeGAField
        , sameFieldType
        , flatten
        , flatten'
@@ -19,391 +17,5 @@
        , showFlat
        ) where
 
-import GHC.Generics
-
-import Control.Lens ( Lens', (^.) )
-import Data.List ( intercalate )
-import qualified Linear
-import GHC.Word
-import Data.Int
-import Foreign.C.Types
-
-import SpatialMath ( Euler )
-import SpatialMathT ( V3T(..), Rot(..) )
-
-showAccTree :: String -> AccessorTree a -> [String]
-showAccTree spaces (Field _) = [spaces ++ "Field {}"]
-showAccTree spaces (Data name trees) =
-  (spaces ++ "Data " ++ show name) :
-  concatMap (showChild (spaces ++ "    ")) trees
-
-showChild :: String -> (String, AccessorTree a) -> [String]
-showChild spaces (name, tree) =
-  (spaces ++ name) : showAccTree (spaces ++ "    ") tree
-
-instance Show (AccessorTree a) where
-  show = unlines . showAccTree ""
-
-data AccessorTree a = Data (String,String) [(String, AccessorTree a)]
-                    | Field (Field a)
-
-data Field a =
-  FieldBool (Lens' a Bool)
-  | FieldDouble (Lens' a Double)
-  | FieldFloat (Lens' a Float)
-  | FieldInt (Lens' a Int)
-  | FieldString (Lens' a String)
-  | FieldSorry -- ^ a field which is not yet supported
-
--- | Return the type of field, such as "Bool", "Double", "String", etc.
-describeField :: Field a -> String
-describeField (FieldBool _) = "Bool"
-describeField (FieldDouble _) = "Double"
-describeField (FieldFloat _) = "Float"
-describeField (FieldInt _) = "Int"
-describeField (FieldString _) = "String"
-describeField FieldSorry = "Sorry"
-
--- | Returns True if the __type__ of fields is the same.
-sameFieldType :: Field a -> Field b -> Bool
-sameFieldType (FieldBool _) (FieldBool _) = True
-sameFieldType (FieldDouble _) (FieldDouble _) = True
-sameFieldType (FieldFloat _) (FieldFloat _) = True
-sameFieldType (FieldInt _) (FieldInt _) = True
-sameFieldType (FieldString _) (FieldString _) = True
-sameFieldType FieldSorry FieldSorry = True
-sameFieldType _ _ = False
-
-accessors :: Lookup a => AccessorTree a
-accessors = toAccessorTree id
-
-showMsgs :: [String] -> String
-showMsgs = intercalate "."
-
-flatten :: AccessorTree a -> [(String, Field a)]
-flatten = map f . flatten'
-  where
-    f (x,y) = (showMsgs x, y)
-
-flatten' :: AccessorTree a -> [([String], Field a)]
-flatten' = flattenChain []
-  where
-    flattenChain :: [String] -> AccessorTree a -> [([String], Field a)]
-    flattenChain msgs (Field lens) = [(reverse msgs, lens)]
-    flattenChain msgs (Data (_,_) trees) = concatMap f trees
-      where
-        f (name,tree) = flattenChain (name:msgs) tree
-
--- | Things which you can make a tree of labeled getters for.
--- You should derive this using GHC.Generics.
-class Lookup a where
-  toAccessorTree :: Lens' b a -> AccessorTree b
-
-  default toAccessorTree :: (Generic a, GLookup (Rep a))
-                            => Lens' b a -> AccessorTree b
-  toAccessorTree lens0 = gtoAccessorTree (lens0 . repLens)
-    where
-      repLens :: Lens' a (Rep a p)
-      repLens f y = fmap to (f (from y))
-
-class GLookup f where
-  gtoAccessorTree :: Lens' b (f a) -> AccessorTree b
-
-class GLookupS f where
-  gtoAccessorTreeS :: Lens' b (f a)
-                      -> [(String, AccessorTree b)]
-
-instance Lookup f => GLookup (Rec0 f) where
-  gtoAccessorTree lens0 = toAccessorTree (lens0 . rec0Lens)
-    where
-      rec0Lens :: Lens' (Rec0 f a) f
-      rec0Lens f y = fmap K1 (f (unK1 y))
-
-instance (Selector s, GLookup a) => GLookupS (S1 s a) where
-  gtoAccessorTreeS lens0 = [(selname, gtoAccessorTree (lens0 . m1Lens))]
-    where
-      m1Lens :: Lens' (S1 s f p) (f p)
-      m1Lens f y = fmap M1 (f (unM1 y))
-
-      selname = case selName selError of
-        "" -> "()"
-        y -> y
-
-      selError :: S1 s a p
-      selError = error $ "generic-accessors: selName should never access data"
-
-
-instance GLookupS U1 where
-  gtoAccessorTreeS _ = []
-
-instance (GLookupS f, GLookupS g) => GLookupS (f :*: g) where
-  gtoAccessorTreeS lens0 = tf ++ tg
-    where
-      tf = gtoAccessorTreeS (lens0 . leftLens)
-      tg = gtoAccessorTreeS (lens0 . rightLens)
-
-      leftLens ::  Lens' ((f :*: g) a) (f a)
-      leftLens  f (x :*: y) = fmap (\x' -> x' :*: y ) (f x)
-      rightLens :: Lens' ((f :*: g) a) (g a)
-      rightLens f (x :*: y) = fmap (\y' -> x  :*: y') (f y)
-
-instance (Datatype d, Constructor c, GLookupS a)
-         => GLookup (D1 d (C1 c a)) where
-  gtoAccessorTree lens0 = Data (datatypeName datatypeError, conName conError) con
-    where
-      conError :: C1 c a p
-      conError = error $ "generic-accessors: conName should never access data"
-
-      datatypeError :: D1 d (C1 c a) p
-      datatypeError = error $ "generic-accessors: datatypeName should never access data"
-
-      con = gtoAccessorTreeS (lens0 . m1m1Lens)
-
-      m1m1Lens :: Lens' (D1 d (C1 c f) p) (f p)
-      m1m1Lens f y = fmap (M1 . M1) (f (unM1 (unM1 y)))
-
--- tuple instances
-instance (Lookup a, Lookup b) => Lookup (a, b) where
-  toAccessorTree lens0 =
-    Data ("(,)", "(,)")
-    [ ("(x,_)", toAccessorTree (lens0 . lens1))
-    , ("(_,x)", toAccessorTree (lens0 . lens2))
-    ]
-    where
-      lens1 ::  Lens' (a, b) a
-      lens1 f (x, y) = fmap (\x' -> (x', y)) (f x)
-      lens2 :: Lens' (a, b) b
-      lens2 f (x, y) = fmap (\y' -> (x, y')) (f y)
-
-instance (Lookup a, Lookup b, Lookup c) => Lookup (a, b, c) where
-  toAccessorTree lens0 =
-    Data ("(,,)", "(,,)")
-    [ ("(x,_,_)", toAccessorTree (lens0 . lens1))
-    , ("(_,x,_)", toAccessorTree (lens0 . lens2))
-    , ("(_,_,x)", toAccessorTree (lens0 . lens3))
-    ]
-    where
-      lens1 ::  Lens' (a, b, c) a
-      lens1 f (x, y, z) = fmap (\x' -> (x', y, z)) (f x)
-      lens2 :: Lens' (a, b, c) b
-      lens2 f (x, y, z) = fmap (\y' -> (x, y', z)) (f y)
-      lens3 :: Lens' (a, b, c) c
-      lens3 f (x, y, z) = fmap (\z' -> (x, y, z')) (f z)
-
-instance (Lookup a, Lookup b, Lookup c, Lookup d) => Lookup (a, b, c, d) where
-  toAccessorTree lens0 =
-    Data ("(,,,)", "(,,,)")
-    [ ("(x,_,_,_)", toAccessorTree (lens0 . lens1))
-    , ("(_,x,_,_)", toAccessorTree (lens0 . lens2))
-    , ("(_,_,x,_)", toAccessorTree (lens0 . lens3))
-    , ("(_,_,_,x)", toAccessorTree (lens0 . lens4))
-    ]
-    where
-      lens1 ::  Lens' (a, b, c, d) a
-      lens1 f (x, y, z, w) = fmap (\x' -> (x', y, z, w)) (f x)
-      lens2 :: Lens' (a, b, c, d) b
-      lens2 f (x, y, z, w) = fmap (\y' -> (x, y', z, w)) (f y)
-      lens3 :: Lens' (a, b, c, d) c
-      lens3 f (x, y, z, w) = fmap (\z' -> (x, y, z', w)) (f z)
-      lens4 :: Lens' (a, b, c, d) d
-      lens4 f (x, y, z, w) = fmap (\w' -> (x, y, z, w')) (f w)
-
-
-
--- some instance from linear
-instance Lookup a => Lookup (Linear.V0 a) where
-  toAccessorTree _ =
-    Data ("V0", "V0") []
-instance Lookup a => Lookup (Linear.V1 a) where
-  toAccessorTree lens0 =
-    Data ("V1", "V1") [ ("x", toAccessorTree (lens0 . Linear._x))
-                      ]
-
-instance Lookup a => Lookup (Linear.V2 a) where
-  toAccessorTree lens0 =
-    Data ("V2", "V2") [ ("x", toAccessorTree (lens0 . Linear._x))
-                      , ("y", toAccessorTree (lens0 . Linear._y))
-                      ]
-
-instance Lookup a => Lookup (Linear.V3 a) where
-  toAccessorTree lens0 =
-    Data ("V3", "V3") [ ("x", toAccessorTree (lens0 . Linear._x))
-                      , ("y", toAccessorTree (lens0 . Linear._y))
-                      , ("z", toAccessorTree (lens0 . Linear._z))
-                      ]
-instance Lookup a => Lookup (Linear.V4 a) where
-  toAccessorTree lens0 =
-    Data ("V4", "V4") [ ("x", toAccessorTree (lens0 . Linear._x))
-                      , ("y", toAccessorTree (lens0 . Linear._y))
-                      , ("z", toAccessorTree (lens0 . Linear._z))
-                      , ("w", toAccessorTree (lens0 . Linear._w))
-                      ]
-instance Lookup a => Lookup (Linear.Quaternion a) where
-  toAccessorTree lens0 =
-    Data ("Quaternion", "Quaternion")
-    [ ("q0", toAccessorTree (lens0 . Linear._e))
-    , ("q1", toAccessorTree (lens0 . Linear._i))
-    , ("q2", toAccessorTree (lens0 . Linear._j))
-    , ("q3", toAccessorTree (lens0 . Linear._k))
-    ]
-
--- basic types
-instance Lookup () where -- hack to get dummy tree
-  toAccessorTree _ = Field FieldSorry
-instance Lookup Int where
-  toAccessorTree lens = Field (FieldInt lens)
-instance Lookup Float where
-  toAccessorTree lens = Field (FieldFloat lens)
-instance Lookup Double where
-  toAccessorTree lens = Field (FieldDouble lens)
-instance Lookup Bool where
-  toAccessorTree lens = Field (FieldBool lens)
-instance Lookup String where
-  toAccessorTree lens = Field (FieldString lens)
-
--- Word types
-instance Lookup Word where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-instance Lookup Word8 where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-instance Lookup Word16 where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-instance Lookup Word32 where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-instance Lookup Word64 where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-
--- Int types
-instance Lookup Int8 where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-instance Lookup Int16 where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-instance Lookup Int32 where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-instance Lookup Int64 where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-
--- C types
--- todo(greg): some of these have inappropriate fields
-instance Lookup CChar where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-instance Lookup CSChar where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-instance Lookup CUChar where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-instance Lookup CShort where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-instance Lookup CUShort where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-instance Lookup CInt where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-instance Lookup CUInt where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-instance Lookup CLong where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-instance Lookup CULong where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-instance Lookup CPtrdiff where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-instance Lookup CSize where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-instance Lookup CWchar where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-instance Lookup CSigAtomic where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-instance Lookup CLLong where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-instance Lookup CULLong where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-instance Lookup CIntPtr where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-instance Lookup CUIntPtr where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-instance Lookup CIntMax where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-instance Lookup CUIntMax where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . integralLens))
-instance Lookup CClock where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . clockLens))
-    where
-      clockLens f (CClock x) = fmap (CClock . fromIntegral) (f (fromIntegral x))
-instance Lookup CTime where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . timeLens))
-    where
-      timeLens f (CTime x) = fmap (CTime . fromIntegral) (f (fromIntegral x))
-instance Lookup CUSeconds where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . usecondsLens))
-    where
-      usecondsLens f (CUSeconds x) = fmap (CUSeconds . fromIntegral) (f (fromIntegral x))
-instance Lookup CSUSeconds where
-  toAccessorTree lens0 = Field (FieldInt (lens0 . susecondsLens))
-    where
-      susecondsLens f (CSUSeconds x) = fmap (CSUSeconds . fromIntegral) (f (fromIntegral x))
-instance Lookup CFloat where
-  toAccessorTree lens0 = Field (FieldDouble (lens0 . realFracLens))
-instance Lookup CDouble where
-  toAccessorTree lens0 = Field (FieldDouble (lens0 . realFracLens))
-
-{-# INLINE integralLens #-}
-integralLens :: Integral a => Lens' a Int
-integralLens f x = fmap fromIntegral (f (fromIntegral x))
-
-{-# INLINE realFracLens #-}
-realFracLens :: (Fractional a, Real a) => Lens' a Double
-realFracLens f x = fmap realToFrac (f (realToFrac x))
-
--- other types
-instance Lookup a => Lookup (Rot f1 f2 a) where
-  toAccessorTree lens0 = toAccessorTree (lens0 . (\f x -> fmap Rot (f (unR x))))
-instance Lookup a => Lookup (V3T f a) where
-  toAccessorTree lens0 = toAccessorTree (lens0 . (\f x -> fmap V3T (f (unV x))))
-instance Lookup a => Lookup (Euler a)
-
-showAccTrees :: (Double -> String) -> a -> [(String, AccessorTree a)] -> String -> [String]
-showAccTrees show' x trees spaces = concat cs ++ [spaces ++ "}"]
-  where
-    cs = zipWith (showRecordField show' x spaces) trees ("{ " : repeat ", ")
-
-showVal :: Field a -> (Double -> String) -> a -> String
-showVal (FieldBool lens) _ x = show (x ^. lens)
-showVal (FieldInt lens) _ x = show (x ^. lens)
-showVal (FieldDouble lens) show' x = show' (x ^. lens)
-showVal (FieldFloat lens) show' x = show' (realToFrac (x ^. lens))
-showVal (FieldString lens) _ x = x ^. lens
-showVal FieldSorry _ _ = ""
-
-showRecordField :: (Double -> String) -> a -> String -> (String, AccessorTree a) -> String -> [String]
-showRecordField show' x spaces (getterName, (Field field)) prefix =
-  [spaces ++ prefix ++ getterName ++ " = " ++ showVal field show' x]
-showRecordField show' x spaces (getterName, Data (_,cons) trees) prefix =
-  (spaces ++ prefixNameEq ++ cons) : showAccTrees show' x trees newSpaces
-  where
-    prefixNameEq = prefix ++ getterName ++ " = "
-    newSpaces = spaces ++ (replicate (length prefixNameEq) ' ')
-
--- version of (init . unlines) which doesn't throw an error on empty input
-initUnlines :: [String] -> [Char]
-initUnlines [] = ""
-initUnlines xs = init (unlines xs)
-
--- | Show a tree of values
-showTree :: AccessorTree a -> (Double -> String) -> a -> String
-showTree (Data (_,cons) trees) show' x = initUnlines $ cons : showAccTrees show' x trees ""
-showTree (Field field) show' x = showVal field show' x
-
--- | Show a list of values
--- .
--- True --> align the colums, False --> total mayhem
-showFlat :: forall a . AccessorTree a -> Bool -> (Double -> String) -> a -> String
-showFlat at align show' x = initUnlines $ map f fl
-  where
-    n = maximum (map (length . fst) fl)
-
-    f (name, lens) = name ++ spaces ++ " = " ++ showVal lens show' x
-      where
-        spaces
-          | align = replicate (n - length name) ' '
-          | otherwise = ""
-
-    fl :: [(String, Field a)]
-    fl = flatten at
+import Accessors.Accessors
+import Accessors.Instances ()
diff --git a/src/Accessors/Accessors.hs b/src/Accessors/Accessors.hs
new file mode 100644
--- /dev/null
+++ b/src/Accessors/Accessors.hs
@@ -0,0 +1,385 @@
+{-# OPTIONS_GHC -Wall #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE DefaultSignatures #-}
+{-# LANGUAGE TypeOperators #-}
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE InstanceSigs #-}
+
+module Accessors.Accessors
+       ( Lookup(..)
+       , AccessorTree
+       , GAData(..)
+       , GAConstructor(..)
+       , GASimpleEnum(..)
+       , GAField(..)
+       , GATip(..)
+       , accessors
+       , describeGAField
+       , sameFieldType
+       , flatten
+       , flatten'
+       , showTree
+       , showFlat
+       ) where
+
+import GHC.Generics
+
+import Control.Lens ( Lens', Prism', (^.), (.~), preview, prism, withPrism )
+import Data.List ( intercalate )
+import Text.Printf ( printf )
+
+type AccessorTree a = Either (GAField a) (GAData a)
+
+data GAData a = GAData String (GAConstructor a)
+
+data GAConstructor a =
+  GAConstructor String [(Maybe String, AccessorTree a)]
+  | GASum (GASimpleEnum a)
+
+data GASimpleEnum a =
+  GASimpleEnum
+  { eConstructors :: [String]
+  , eToString :: a -> String
+  , eToIndex :: a -> Int
+  , eFromString :: a -> String -> Either String a
+  , eFromIndex :: a -> Int -> Either String a
+  }
+
+data GAField a =
+  FieldDouble (Lens' a Double)
+  | FieldFloat (Lens' a Float)
+  | FieldInt (Lens' a Int)
+  | FieldString (Lens' a String)
+  | FieldSorry -- ^ a field which is not yet supported
+
+data GATip a =
+  GATipSimpleEnum (GASimpleEnum a)
+  | GATipField (GAField a)
+
+showGAData :: String -> GAData a -> [String]
+showGAData spaces (GAData name constructors) =
+  (spaces ++ "Data " ++ show name) :
+  showGAConstructor (spaces ++ "    ") constructors
+
+showGAConstructor :: String -> GAConstructor a -> [String]
+showGAConstructor spaces (GASum e) = [spaces ++ "[" ++ intercalate ", " (eConstructors e) ++ "]"]
+showGAConstructor spaces (GAConstructor name fields) =
+  (spaces ++ name) : concatMap (showGAField (spaces ++ "    ")) fields
+
+showGAField :: String -> (Maybe String, AccessorTree a) -> [String]
+showGAField spaces (name, Left f) = [spaces ++ showMName name ++ " " ++ describeGAField f]
+showGAField spaces (name, Right field) =
+  showMName name :
+  showGAData (spaces ++ "    ") field
+
+showMName :: Maybe String -> String
+showMName (Just n) = n
+showMName Nothing = "()"
+
+instance Show (GAData a) where
+  show = unlines . showGAData ""
+
+-- | Return the type of field, such as "Bool", "Double", "String", etc.
+describeGAField :: GAField a -> String
+describeGAField (FieldDouble _) = "Double"
+describeGAField (FieldFloat _) = "Float"
+describeGAField (FieldInt _) = "Int"
+describeGAField (FieldString _) = "String"
+describeGAField FieldSorry = "Sorry"
+
+-- | Returns True if the __type__ of fields is the same.
+sameFieldType :: GAField a -> GAField b -> Bool
+sameFieldType (FieldDouble _) (FieldDouble _) = True
+sameFieldType (FieldFloat _) (FieldFloat _) = True
+sameFieldType (FieldInt _) (FieldInt _) = True
+sameFieldType (FieldString _) (FieldString _) = True
+sameFieldType FieldSorry FieldSorry = True
+sameFieldType (FieldDouble _) _ = False
+sameFieldType (FieldFloat _) _ = False
+sameFieldType (FieldInt _) _ = False
+sameFieldType (FieldString _) _ = False
+sameFieldType FieldSorry _ = False
+
+accessors :: Lookup a => AccessorTree a
+accessors = toAccessorTree id
+
+showMsgs :: [Maybe String] -> String
+showMsgs = intercalate "." . map showMName
+
+flatten :: AccessorTree a -> [(String, GATip a)]
+flatten = map f . flatten'
+  where
+    f (x,y) = (showMsgs x, y)
+
+flatten' :: AccessorTree a -> [([Maybe String], GATip a)]
+flatten' = flattenChain []
+  where
+    flattenChain :: [Maybe String] -> AccessorTree a -> [([Maybe String], GATip a)]
+    flattenChain msgs (Left f) = [(reverse msgs, GATipField f)]
+    flattenChain msgs (Right (GAData _ (GASum simpleEnum))) = [(reverse msgs, GATipSimpleEnum simpleEnum)]
+    flattenChain msgs (Right (GAData _ (GAConstructor _ trees))) = concatMap f trees
+      where
+        f :: (Maybe String, AccessorTree a) -> [([Maybe String], GATip a)]
+        f (name, tree) = flattenChain (name:msgs) tree
+
+-- | Things which you can make a tree of labeled getters for.
+-- You should derive this using GHC.Generics.
+class Lookup a where
+  toAccessorTree :: Lens' b a -> AccessorTree b
+
+  default toAccessorTree :: (Generic a, GLookup (Rep a)) => Lens' b a -> AccessorTree b
+  toAccessorTree lens0 = gtoAccessorTree (lens0 . repLens)
+    where
+      repLens :: Lens' a (Rep a p)
+      repLens f y = fmap to (f (from y))
+
+class GLookup f where
+  gtoAccessorTree :: Lens' b (f a) -> AccessorTree b
+
+class GLookupS f where
+  gtoAccessorTreeS :: Lens' b (f a) -> [(Maybe String, AccessorTree b)]
+
+instance Lookup f => GLookup (Rec0 f) where
+  gtoAccessorTree :: Lens' b (Rec0 f p) -> AccessorTree b
+  gtoAccessorTree lens0 = toAccessorTree (lens0 . rec0Lens)
+    where
+      rec0Lens :: Lens' (Rec0 f a) f
+      rec0Lens f y = fmap K1 (f (unK1 y))
+
+class GEnum a where
+  gtoSimpleEnum :: Prism' b (a p) -> [(String, b, b -> Bool)]
+
+instance Constructor c => GEnum (C1 c U1) where
+  gtoSimpleEnum :: forall b p . Prism' b (C1 c U1 p) -> [(String, b, b -> Bool)]
+  gtoSimpleEnum pr = [(cname, thisOne, isThisOne)]
+    where
+      thisOne :: b
+      thisOne = withPrism pr $ \f _ -> f (M1 U1 :: C1 c U1 p)
+
+      isThisOne :: b -> Bool
+      isThisOne b = case preview pr b :: Maybe (C1 c U1 p) of
+        Nothing -> False
+        Just _ -> True
+
+      cname = conName conError
+
+      conError :: C1 c a p
+      conError = error $ "generic-accessors: conName should never access data"
+
+instance (GEnum c1, GEnum c2) => GEnum (c1 :+: c2) where
+  gtoSimpleEnum :: forall b p . Prism' b ((c1 :+: c2) p) -> [(String, b, b -> Bool)]
+  gtoSimpleEnum pr0 = c1s ++ c2s
+    where
+      c1s = gtoSimpleEnum ((pr0 . leftPrism) :: Prism' b (c1 p))
+      c2s = gtoSimpleEnum ((pr0 . rightPrism) :: Prism' b (c2 p))
+
+      leftPrism :: Prism' ((c1 :+: c2) p) (c1 p)
+      leftPrism = prism remitter reviewer
+        where
+          remitter = L1
+          reviewer (L1 l) = Right l
+          reviewer x = Left x
+
+      rightPrism :: Prism' ((c1 :+: c2) p) (c2 p)
+      rightPrism = prism remitter reviewer
+        where
+          remitter = R1
+          reviewer (R1 l) = Right l
+          reviewer x = Left x
+
+instance (Datatype d, GEnum (c1 :+: c2)) => GLookup (D1 d (c1 :+: c2)) where
+  gtoAccessorTree :: forall b p . Lens' b (D1 d (c1 :+: c2) p) -> AccessorTree b
+  gtoAccessorTree lens0 = Right $ GAData (datatypeName datatypeError) constructor
+    where
+      datatypeError :: D1 d (c1 :+: c2) p
+      datatypeError = error $ "generic-accessors: datatypeName should never access data"
+
+      constructor :: GAConstructor b
+      constructor =
+        GASum
+        GASimpleEnum
+        { eConstructors = options
+        , eToString = toString
+        , eToIndex = toIndex
+        , eFromIndex = fromIndex
+        , eFromString = fromString
+        }
+        where
+          options = map fst3 simpleEnums
+            where
+              fst3 (x,_,_) = x
+
+          fromIndex x k
+            | k < 0 =
+                Left $
+                printf "generic-accessors: Error converting Int to Enum: requested negative index (%d)" k
+            | k >= length options =
+                Left $
+                "generic-accessors: Error converting Int to Enum.\n" ++
+                printf "Requested index %d but there are only %d options." k (length simpleEnums)
+            | otherwise = Right $ (lens0 . m1Lens . intLens .~ k) x
+
+          fromString x name = fromString' 0 options
+            where
+              fromString' k (opt:opts)
+                | name == opt = fromIndex x k
+                | otherwise = fromString' (k+1) opts
+              fromString' _ [] =
+                Left $
+                "generic-accessors: Error converting from String to Enum: "
+                ++ show name ++ "is not one of the constructors."
+
+          toIndex x = x ^. (lens0 . m1Lens . intLens)
+          toString x = case safeIndex options index of
+            Just r -> r
+            Nothing -> error $ unlines
+                       [ "generic-accessors: eToString: the \"impossible\" happened"
+                       , printf "Enum is out of bounds (index %d, length %d)." index (length options)
+                       ]
+            where
+              index = toIndex x
+
+      simpleEnums :: [(String, (c1 :+: c2) p, (c1 :+: c2) p -> Bool)]
+      simpleEnums = gtoSimpleEnum id
+
+      intLens :: Lens' ((c1 :+: c2) p) Int
+      intLens f y = fmap fromInt' (f (toInt y))
+
+      fromInt' :: Int -> (c1 :+: c2) p
+      fromInt' k = case fromInt k of
+        Right r -> r
+        Left e -> error e
+
+      fromInt :: Int -> Either String ((c1 :+: c2) p)
+      fromInt k = case safeIndex simpleEnums k of
+        Nothing -> Left $
+                   "generic-accessors:\n" ++
+                   "Error converting Int to Enum.\n" ++
+                   printf "Requested index %d but there are only %d options." k (length simpleEnums)
+        Just (_, x, _) -> Right x
+
+      toInt :: (c1 :+: c2) p -> Int
+      toInt x = toInt' 0 simpleEnums
+        where
+          toInt' k ((_, _, isVal):others)
+            | isVal x = k
+            | otherwise = toInt' (k+1) others
+          toInt' _ [] =
+            error $ unlines
+            [ "generic-accessors:"
+            , "The \"impossible\" happened converting Enum to Int."
+            , "No enum matched the provided one."
+            ]
+
+      safeIndex :: [a] -> Int -> Maybe a
+      safeIndex (x:_) 0 = Just x
+      safeIndex (_:xs) k = safeIndex xs (k-1)
+      safeIndex [] _ = Nothing
+
+m1Lens :: Lens' (M1 i c f p) (f p)
+m1Lens f y = fmap M1 (f (unM1 y))
+
+instance (Datatype d, Constructor c, GLookupS a) => GLookup (D1 d (C1 c a)) where
+  gtoAccessorTree :: forall b p . Lens' b (D1 d (C1 c a) p) -> AccessorTree b
+  gtoAccessorTree lens0 = Right $ GAData (datatypeName datatypeError) constructor
+    where
+      datatypeError :: D1 d (C1 c a) p
+      datatypeError = error $ "generic-accessors: datatypeName should never access data"
+
+      constructor :: GAConstructor b
+      constructor = gtoAccessorTreeC (lens0 . m1Lens)
+
+gtoAccessorTreeC :: forall c b a p . (Constructor c, GLookupS a) => Lens' b (C1 c a p) -> GAConstructor b
+gtoAccessorTreeC lens0 = GAConstructor (conName conError) (gtoAccessorTreeS (lens0 . m1Lens))
+  where
+    conError :: C1 c a p
+    conError = error $ "generic-accessors: conName should never access data"
+
+instance (Selector s, GLookup a) => GLookupS (S1 s a) where
+  gtoAccessorTreeS :: Lens' b (S1 s a p) -> [(Maybe String, AccessorTree b)]
+  gtoAccessorTreeS lens0 = [(selname, gtoAccessorTree (lens0 . m1Lens))]
+    where
+      selname = case selName selError of
+        "" -> Nothing
+        y -> Just y
+
+      selError :: S1 s a p
+      selError = error $ "generic-accessors: selName should never access data"
+
+instance GLookupS U1 where
+  gtoAccessorTreeS :: Lens' b (U1 p) -> [(Maybe String, AccessorTree b)]
+  gtoAccessorTreeS _ = []
+
+instance (GLookupS f, GLookupS g) => GLookupS (f :*: g) where
+  gtoAccessorTreeS :: Lens' b ((f :*: g) p) -> [(Maybe String, AccessorTree b)]
+  gtoAccessorTreeS lens0 = tf ++ tg
+    where
+      tf = gtoAccessorTreeS (lens0 . leftLens)
+      tg = gtoAccessorTreeS (lens0 . rightLens)
+
+      leftLens ::  Lens' ((f :*: g) a) (f a)
+      leftLens  f (x :*: y) = fmap (\x' -> x' :*: y ) (f x)
+
+      rightLens :: Lens' ((f :*: g) a) (g a)
+      rightLens f (x :*: y) = fmap (\y' -> x  :*: y') (f y)
+
+
+showAccTrees :: (Double -> String) -> a
+                -> [(Maybe String, AccessorTree a)] -> String
+                -> [String]
+showAccTrees show' x trees spaces = concat cs ++ [spaces ++ "}"]
+  where
+    cs = zipWith (showRecordField show' x spaces) trees ("{ " : repeat ", ")
+
+showFieldVal :: GAField a -> (Double -> String) -> a -> String
+showFieldVal (FieldInt lens) _ x = show (x ^. lens)
+showFieldVal (FieldDouble lens) show' x = show' (x ^. lens)
+showFieldVal (FieldFloat lens) show' x = show' (realToFrac (x ^. lens))
+showFieldVal (FieldString lens) _ x = x ^. lens
+showFieldVal FieldSorry _ _ = ""
+
+showTipVal :: GATip a -> (Double -> String) -> a -> String
+showTipVal (GATipField f) sh x = showFieldVal f sh x
+showTipVal (GATipSimpleEnum simpleEnum) _ x = eToString simpleEnum x
+
+showRecordField :: (Double -> String) -> a -> String -> (Maybe String, AccessorTree a) -> String -> [String]
+showRecordField show' x spaces (getterName, (Left field)) prefix =
+  [spaces ++ prefix ++ showMName getterName ++ " = " ++ showFieldVal field show' x]
+showRecordField _ x spaces (getterName, Right (GAData _ (GASum simpleEnum))) prefix =
+  [spaces ++ prefix ++ showMName getterName ++ " = " ++ eToString simpleEnum x]
+showRecordField show' x spaces (getterName, Right (GAData _ (GAConstructor cons trees))) prefix =
+  (spaces ++ prefixNameEq ++ cons) : showAccTrees show' x trees newSpaces
+  where
+    prefixNameEq = prefix ++ showMName getterName ++ " = "
+    newSpaces = spaces ++ (replicate (length prefixNameEq) ' ')
+
+-- version of (init . unlines) which doesn't throw an error on empty input
+initUnlines :: [String] -> [Char]
+initUnlines [] = ""
+initUnlines xs = init (unlines xs)
+
+-- | Show a tree of values
+showTree :: AccessorTree a -> (Double -> String) -> a -> String
+showTree (Right (GAData _ (GASum simpleEnum))) _ x = eToString simpleEnum x
+showTree (Right (GAData _ (GAConstructor cons trees))) show' x =
+  initUnlines $ cons : showAccTrees show' x trees ""
+showTree (Left field) show' x = showFieldVal field show' x
+
+-- | Show a list of values
+-- .
+-- True --> align the colums, False --> total mayhem
+showFlat :: forall a . AccessorTree a -> Bool -> (Double -> String) -> a -> String
+showFlat at align show' x = initUnlines $ map f fl
+  where
+    n = maximum (map (length . fst) fl)
+
+    f (name, lens) = name ++ spaces ++ " = " ++ showTipVal lens show' x
+      where
+        spaces
+          | align = replicate (n - length name) ' '
+          | otherwise = ""
+
+    fl :: [(String, GATip a)]
+    fl = flatten at
diff --git a/src/Accessors/Dynamic.hs b/src/Accessors/Dynamic.hs
new file mode 100644
--- /dev/null
+++ b/src/Accessors/Dynamic.hs
@@ -0,0 +1,221 @@
+{-# OPTIONS_GHC -Wall #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE DeriveDataTypeable #-}
+
+module Accessors.Dynamic
+       ( DTree, DData(..), DConstructor(..), DSimpleEnum(..), DField(..)
+       , toDData, updateLookupable, describeDField, sameDFieldType
+         -- * some utility functions for working with DSimpleEnums
+       , denumToString, denumToStringOrMsg, denumSetString, denumSetIndex
+       ) where
+
+import GHC.Generics
+
+import Data.Binary ( Binary )
+import Data.Serialize ( Serialize )
+import Data.Data ( Data )
+import Data.List ( intercalate )
+import Data.Typeable ( Typeable )
+import Control.Lens
+import Text.Printf ( printf )
+
+import Accessors
+
+type DTree = Either DField DData
+
+data DData = DData String DConstructor
+           deriving (Generic, Show, Eq, Ord, Data, Typeable)
+instance Serialize DData
+instance Binary DData
+
+data DConstructor =
+  DConstructor String [(Maybe String, DTree)]
+  | DSum DSimpleEnum
+  deriving (Generic, Show, Eq, Ord, Data, Typeable)
+instance Serialize DConstructor
+instance Binary DConstructor
+
+data DSimpleEnum = DSimpleEnum [String] Int
+                 deriving (Generic, Show, Eq, Ord, Data, Typeable)
+instance Serialize DSimpleEnum
+instance Binary DSimpleEnum
+
+-- | a dynamic field
+data DField =
+  DDouble Double
+  | DFloat Float
+  | DInt Int
+  | DString String
+  | DSorry
+  deriving (Generic, Show, Eq, Ord, Data, Typeable)
+instance Serialize DField
+instance Binary DField
+
+-- | Get the constructor string or an error message.
+denumToString :: DSimpleEnum -> Either String String
+denumToString (DSimpleEnum _ k)
+  | k < 0 = Left $ printf "denumToString: index %d is negative" k
+denumToString (DSimpleEnum constructors k) = safeIndex constructors k
+  where
+    safeIndex (x:_) 0 = Right x
+    safeIndex (_:xs) j = safeIndex xs (j-1)
+    safeIndex [] _ =
+      Left $
+      printf "denumToString: index %d is too large (%d constructors)" k (length constructors)
+
+-- | Get the constructor string or an error message without telling which is which.
+denumToStringOrMsg :: DSimpleEnum -> String
+denumToStringOrMsg d = case denumToString d of
+  Left msg -> msg
+  Right r -> r
+
+-- | Try to update an enum with its constructor. Fail if not a valid constructor.
+denumSetString :: DSimpleEnum -> String -> Either String DSimpleEnum
+denumSetString (DSimpleEnum options _) txt = safeLookup options 0
+  where
+    safeLookup (opt:opts) k
+      | opt == txt = Right (DSimpleEnum options k)
+      | otherwise = safeLookup opts (k + 1)
+    safeLookup [] _ = Left $ printf "denumSetString: %s is not a valid constructor" txt
+
+-- | Try to update an enum with its index. Fail if out of bounds.
+denumSetIndex :: DSimpleEnum -> Int -> Either String DSimpleEnum
+denumSetIndex (DSimpleEnum constructors _) k
+  | k < 0 = Left $ printf "denumSetIndex: index %d is negative" k
+  | k >= length constructors =
+      Left $
+      printf "denumSetIndex: index %d is too large (%d constructors)" k (length constructors)
+  | otherwise = Right $ DSimpleEnum constructors k
+
+-- | Returns True if the __type__ of fields is the same.
+sameDFieldType :: DField -> DField -> Bool
+sameDFieldType (DDouble _) (DDouble _) = True
+sameDFieldType (DFloat _) (DFloat _) = True
+sameDFieldType (DInt _) (DInt _) = True
+sameDFieldType (DString _) (DString _) = True
+sameDFieldType DSorry DSorry = True
+sameDFieldType (DDouble _) _ = False
+sameDFieldType (DFloat _) _ = False
+sameDFieldType (DInt _) _ = False
+sameDFieldType (DString _) _ = False
+sameDFieldType DSorry _ = False
+
+describeDField :: DField -> String
+describeDField (DInt _) = "Int"
+describeDField (DDouble _) = "Double"
+describeDField (DFloat _) = "Float"
+describeDField (DString _) = "String"
+describeDField DSorry = "Sorry"
+
+-- | convert to a dynamic value
+toDData :: forall a . Lookup a => a -> DTree
+toDData x = toDData' accessors
+  where
+    toDData' :: Either (GAField a) (GAData a) -> DTree
+    toDData' (Right (GAData dname constructor)) =
+      Right $ DData dname (toDConstructor constructor)
+    toDData' (Left field) = Left (toDField field)
+
+    toDConstructor :: GAConstructor a -> DConstructor
+    toDConstructor (GASum e) =
+      DSum (DSimpleEnum (eConstructors e) (eToIndex e x))
+      
+    toDConstructor (GAConstructor cname fields) =
+      DConstructor cname $ map (\(n, f) -> (n, toDData' f)) fields
+
+    toDField :: GAField a -> DField
+    toDField (FieldInt f) = DInt (x ^. f)
+    toDField (FieldDouble f) = DDouble (x ^. f)
+    toDField (FieldFloat f) = DFloat (x ^. f)
+    toDField (FieldString f) = DString (x ^. f)
+    toDField FieldSorry = DSorry
+
+
+-- | Update something using a dynamic representation
+updateLookupable :: Lookup a => a -> DTree -> Either String a
+updateLookupable x0 dtree = updateData x0 accessors dtree
+
+updateData :: forall a
+                     . a
+                     -> Either (GAField a) (GAData a)
+                     -> DTree
+                     -> Either String a
+updateData x0 (Left afield) (Left dfield) = updateField x0 afield dfield
+updateData x0 (Right (GAData adataName acon)) (Right (DData ddataName dcon))
+  | adataName /= ddataName =
+      Left $
+      "dynamic datatype name " ++ show ddataName ++
+      " don't match accessor datatype names " ++ show adataName
+  | otherwise = updateConstructor x0 acon dcon
+updateData _ (Left field) (Right (DData n _)) =
+  Left $ "got GAField (" ++ describeGAField field ++ ") for accessor tree but DData (" ++ show n ++ ") for dynamic tree"
+updateData _ (Right (GAData n _)) (Left field) =
+  Left $ "got GAData for accessor tree (" ++ show n ++ ") but DField (" ++ describeDField field++ ") for dynamic tree"
+
+showList' :: [String] -> String
+showList' xs = "[" ++ intercalate ", " xs ++ "]"
+
+updateConstructor :: forall a
+                     . a
+                     -> GAConstructor a
+                     -> DConstructor
+                     -> Either String a
+updateConstructor x (GASum aenum) (DSum (DSimpleEnum dnames k))
+  | anames /= dnames =
+      Left $
+      "accessor sum options " ++ showList' anames ++
+      " doesn't match dynamic sum options " ++ showList' dnames
+  | otherwise = eFromIndex aenum x k
+  where
+    anames = eConstructors aenum
+updateConstructor x0 (GAConstructor aconName afields) (DConstructor dconName dfields)
+  | aconName /= dconName =
+      Left $
+      "dynamic constructor name " ++ show dconName ++
+      " don't match accessor constructor names " ++ show aconName
+  | length afields /= length dfields = lengthMismatch
+  | otherwise = f x0 afields dfields
+    where
+      lengthMismatch =
+        Left $
+        "dynamic fields have different length than accessor fields\n" ++
+        "dynamic fields: " ++ show (map fst dfields) ++ "\n" ++
+        "accessor fields: " ++ show (map fst afields)
+        
+      f :: a
+           -> [(Maybe String, Either (GAField a) (GAData a))]
+           -> [(Maybe String, DTree)]
+           -> Either String a
+      f x ((aname, afield):as) ((dname, dfield):ds)
+        | aname /= dname =
+            Left $
+            "accessor selector name " ++ show aname ++
+            " doesn't match dynamic selector name " ++ show dname
+        | otherwise = case updateData x afield dfield of
+            Left msg -> Left $ "error updating selector " ++ show aname ++ ": " ++ msg
+            Right r -> f r as ds
+      f x [] [] = Right x
+      -- this should never happen:
+      f _ _ _ = lengthMismatch
+updateConstructor _ (GAConstructor aconName _) (DSum (DSimpleEnum dnames _)) =
+  Left $ "got GAConstructor (" ++ aconName ++ ") but DSum ([" ++ showList' dnames ++ "])"
+updateConstructor _ (GASum aenum) (DConstructor dconName _) =
+  Left $ "got GASum ([" ++ showList' (eConstructors aenum) ++ "]) but DConstructor (" ++ dconName ++ ")"
+
+
+updateField :: a -> GAField a -> DField -> Either String a
+updateField x0 (FieldDouble f) (DDouble x) = Right $ (f .~ x) x0
+updateField x0 (FieldFloat f) (DFloat x) = Right $ (f .~ x) x0
+updateField x0 (FieldInt f) (DInt x) = Right $ (f .~ x) x0
+updateField x0 (FieldString f) (DString x) = Right $ (f .~ x) x0
+updateField x0 FieldSorry _ = Right x0
+updateField _ f@(FieldDouble _) d = Left (fieldMismatch f d)
+updateField _ f@(FieldFloat _) d = Left (fieldMismatch f d)
+updateField _ f@(FieldInt _) d = Left (fieldMismatch f d)
+updateField _ f@(FieldString _) d = Left (fieldMismatch f d)
+
+fieldMismatch :: GAField a -> DField -> String
+fieldMismatch f d =
+  "accessor GAField " ++ describeGAField f ++
+  " got incompatible dynamic DField " ++ describeDField d
diff --git a/src/Accessors/Instances.hs b/src/Accessors/Instances.hs
new file mode 100644
--- /dev/null
+++ b/src/Accessors/Instances.hs
@@ -0,0 +1,219 @@
+{-# OPTIONS_GHC -Wall -fno-warn-orphans #-}
+{-# LANGUAGE FlexibleInstances #-}
+
+module Accessors.Instances () where
+
+import Control.Lens ( Lens' )
+import qualified Linear
+import GHC.Word
+import Data.Int
+import Foreign.C.Types
+import SpatialMath ( Euler )
+import SpatialMathT ( V3T(..), Rot(..) )
+
+import Accessors.Accessors ( Lookup(..), GAData(..), GAConstructor(..), GAField(..) )
+
+-- tuple instances
+instance (Lookup a, Lookup b) => Lookup (a, b) where
+  toAccessorTree lens0 =
+    Right $
+    GAData "(,)" $
+    GAConstructor "(,)"
+    [ (Just "(x,_)", toAccessorTree (lens0 . lens1))
+    , (Just "(_,x)", toAccessorTree (lens0 . lens2))
+    ]
+    where
+      lens1 ::  Lens' (a, b) a
+      lens1 f (x, y) = fmap (\x' -> (x', y)) (f x)
+
+      lens2 :: Lens' (a, b) b
+      lens2 f (x, y) = fmap (\y' -> (x, y')) (f y)
+
+instance (Lookup a, Lookup b, Lookup c) => Lookup (a, b, c) where
+  toAccessorTree lens0 =
+    Right $
+    GAData "(,,)" $
+    GAConstructor "(,,)"
+    [ (Just "(x,_,_)", toAccessorTree (lens0 . lens1))
+    , (Just "(_,x,_)", toAccessorTree (lens0 . lens2))
+    , (Just "(_,_,x)", toAccessorTree (lens0 . lens3))
+    ]
+    where
+      lens1 ::  Lens' (a, b, c) a
+      lens1 f (x, y, z) = fmap (\x' -> (x', y, z)) (f x)
+      lens2 :: Lens' (a, b, c) b
+      lens2 f (x, y, z) = fmap (\y' -> (x, y', z)) (f y)
+      lens3 :: Lens' (a, b, c) c
+      lens3 f (x, y, z) = fmap (\z' -> (x, y, z')) (f z)
+
+instance (Lookup a, Lookup b, Lookup c, Lookup d) => Lookup (a, b, c, d) where
+  toAccessorTree lens0 =
+    Right $
+    GAData "(,,,)" $
+    GAConstructor "(,,,)"
+    [ (Just "(x,_,_,_)", toAccessorTree (lens0 . lens1))
+    , (Just "(_,x,_,_)", toAccessorTree (lens0 . lens2))
+    , (Just "(_,_,x,_)", toAccessorTree (lens0 . lens3))
+    , (Just "(_,_,_,x)", toAccessorTree (lens0 . lens4))
+    ]
+    where
+      lens1 ::  Lens' (a, b, c, d) a
+      lens1 f (x, y, z, w) = fmap (\x' -> (x', y, z, w)) (f x)
+      lens2 :: Lens' (a, b, c, d) b
+      lens2 f (x, y, z, w) = fmap (\y' -> (x, y', z, w)) (f y)
+      lens3 :: Lens' (a, b, c, d) c
+      lens3 f (x, y, z, w) = fmap (\z' -> (x, y, z', w)) (f z)
+      lens4 :: Lens' (a, b, c, d) d
+      lens4 f (x, y, z, w) = fmap (\w' -> (x, y, z, w')) (f w)
+
+
+-- some instance from linear
+instance Lookup a => Lookup (Linear.V0 a) where
+  toAccessorTree _ =
+    Right $ GAData "V0" $ GAConstructor "V0" []
+instance Lookup a => Lookup (Linear.V1 a) where
+  toAccessorTree lens0 =
+    Right $ GAData "V1" $ GAConstructor "V1"
+    [(Just "x", toAccessorTree (lens0 . Linear._x))]
+
+instance Lookup a => Lookup (Linear.V2 a) where
+  toAccessorTree lens0 =
+    Right $ GAData "V2" $ GAConstructor "V2"
+    [ (Just "x", toAccessorTree (lens0 . Linear._x))
+    , (Just "y", toAccessorTree (lens0 . Linear._y))
+    ]
+
+instance Lookup a => Lookup (Linear.V3 a) where
+  toAccessorTree lens0 =
+    Right $ GAData "V3" $ GAConstructor "V3"
+    [ (Just "x", toAccessorTree (lens0 . Linear._x))
+    , (Just "y", toAccessorTree (lens0 . Linear._y))
+    , (Just "z", toAccessorTree (lens0 . Linear._z))
+    ]
+instance Lookup a => Lookup (Linear.V4 a) where
+  toAccessorTree lens0 =
+    Right $ GAData "V4" $ GAConstructor "V4"
+    [ (Just "x", toAccessorTree (lens0 . Linear._x))
+    , (Just "y", toAccessorTree (lens0 . Linear._y))
+    , (Just "z", toAccessorTree (lens0 . Linear._z))
+    , (Just "w", toAccessorTree (lens0 . Linear._w))
+    ]
+instance Lookup a => Lookup (Linear.Quaternion a) where
+  toAccessorTree lens0 =
+    Right $ GAData "Quaternion" $ GAConstructor "Quaternion"
+    [ (Just "q0", toAccessorTree (lens0 . Linear._e))
+    , (Just "q1", toAccessorTree (lens0 . Linear._i))
+    , (Just "q2", toAccessorTree (lens0 . Linear._j))
+    , (Just "q3", toAccessorTree (lens0 . Linear._k))
+    ]
+
+-- basic types
+instance Lookup () where -- hack to get dummy tree
+  toAccessorTree _ = Left FieldSorry
+instance Lookup Int where
+  toAccessorTree lens = Left (FieldInt lens)
+instance Lookup Float where
+  toAccessorTree lens = Left (FieldFloat lens)
+instance Lookup Double where
+  toAccessorTree lens = Left (FieldDouble lens)
+instance Lookup Bool
+instance Lookup String where
+  toAccessorTree lens = Left (FieldString lens)
+
+-- Word types
+instance Lookup Word where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+instance Lookup Word8 where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+instance Lookup Word16 where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+instance Lookup Word32 where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+instance Lookup Word64 where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+
+-- Int types
+instance Lookup Int8 where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+instance Lookup Int16 where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+instance Lookup Int32 where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+instance Lookup Int64 where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+
+-- C types
+-- todo(greg): some of these have inappropriate fields
+instance Lookup CChar where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+instance Lookup CSChar where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+instance Lookup CUChar where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+instance Lookup CShort where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+instance Lookup CUShort where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+instance Lookup CInt where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+instance Lookup CUInt where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+instance Lookup CLong where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+instance Lookup CULong where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+instance Lookup CPtrdiff where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+instance Lookup CSize where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+instance Lookup CWchar where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+instance Lookup CSigAtomic where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+instance Lookup CLLong where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+instance Lookup CULLong where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+instance Lookup CIntPtr where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+instance Lookup CUIntPtr where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+instance Lookup CIntMax where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+instance Lookup CUIntMax where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . integralLens))
+instance Lookup CClock where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . clockLens))
+    where
+      clockLens f (CClock x) = fmap (CClock . fromIntegral) (f (fromIntegral x))
+instance Lookup CTime where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . timeLens))
+    where
+      timeLens f (CTime x) = fmap (CTime . fromIntegral) (f (fromIntegral x))
+instance Lookup CUSeconds where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . usecondsLens))
+    where
+      usecondsLens f (CUSeconds x) = fmap (CUSeconds . fromIntegral) (f (fromIntegral x))
+instance Lookup CSUSeconds where
+  toAccessorTree lens0 = Left (FieldInt (lens0 . susecondsLens))
+    where
+      susecondsLens f (CSUSeconds x) = fmap (CSUSeconds . fromIntegral) (f (fromIntegral x))
+instance Lookup CFloat where
+  toAccessorTree lens0 = Left (FieldDouble (lens0 . realFracLens))
+instance Lookup CDouble where
+  toAccessorTree lens0 = Left (FieldDouble (lens0 . realFracLens))
+
+{-# INLINE integralLens #-}
+integralLens :: Integral a => Lens' a Int
+integralLens f x = fmap fromIntegral (f (fromIntegral x))
+
+{-# INLINE realFracLens #-}
+realFracLens :: (Fractional a, Real a) => Lens' a Double
+realFracLens f x = fmap realToFrac (f (realToFrac x))
+
+-- other types
+instance Lookup a => Lookup (Rot f1 f2 a) where
+  toAccessorTree lens0 = toAccessorTree (lens0 . (\f x -> fmap Rot (f (unR x))))
+instance Lookup a => Lookup (V3T f a) where
+  toAccessorTree lens0 = toAccessorTree (lens0 . (\f x -> fmap V3T (f (unV x))))
+instance Lookup a => Lookup (Euler a)
diff --git a/tests/Tests.hs b/tests/Tests.hs
--- a/tests/Tests.hs
+++ b/tests/Tests.hs
@@ -13,11 +13,13 @@
 import Test.Framework.Providers.HUnit ( testCase )
 
 import Accessors
+import Accessors.Dynamic
 
 main :: IO ()
 main = do
   defaultMainWithOpts
     [ accessorTests
+    , dynamicTests
     ]
     opts
 
@@ -34,27 +36,29 @@
 data Xyz a = Xyz { xx :: Int
                  , yy :: Double
                  , zz :: Float
+                 , bb :: (Bool, Bool, Bool)
                  , ww :: a
-                 } deriving (Generic)
-data One = MkOne { one :: Double } deriving (Generic)
+                 } deriving (Generic, Show)
+data One = MkOne { one :: Double
+                 } deriving (Generic, Show)
 data Foo = MkFoo { aaa :: Int
                  , bbb :: Xyz Int
                  , lol :: Bool
                  , notlol :: Bool
                  , yoyo :: Xyz (Xyz Double)
                  , ccc :: One
-                 } deriving (Generic)
+                 } deriving (Generic, Show)
 instance Lookup One
 instance Lookup a => Lookup (Xyz a)
 instance Lookup Foo
 
 yo :: Xyz (Xyz Double)
-yo = Xyz 42 45 2000 (Xyz 2 3 4 5)
+yo = Xyz 42 45 2000 (True, True, False) (Xyz 2 3 4 (False, True, False) 5)
 
 foo :: Foo
-foo = MkFoo 2 (Xyz 6 7 8 9) True False yo (MkOne 17)
+foo = MkFoo 2 (Xyz 6 7 8 (True, False, False) 9) True False yo (MkOne 17)
 
-yup :: AccessorTree Foo
+yup :: Either (GAField Foo) (GAData Foo)
 yup = accessors
 
 
@@ -66,6 +70,14 @@
   , testCase "showFlat (aligned)" flatTestAligned
   ]
 
+dynamicTests :: Test
+dynamicTests =
+  testGroup "dynamic"
+  [ testCase "toDValue" toDValueTest
+  , testCase "updateDValueTest" updateDValueTest
+  , testCase "badupdateDValueTest" badUpdateDValueTest
+  ]
+
 assertEqualString :: String -> String -> HUnit.Assertion
 assertEqualString x y = HUnit.assertBool msg (x == y)
   where
@@ -75,6 +87,92 @@
           y ++
           "\n-----------------------------------------------"
 
+assertEqualString' :: Either String String -> Either String String -> HUnit.Assertion
+assertEqualString' ex ey = HUnit.assertBool msg (ex == ey)
+  where
+    x = case ex of
+      Left r -> r
+      Right r -> r
+    y = case ey of
+      Left r -> r
+      Right r -> r
+    msg = "------------------ expected: ------------------\n" ++
+          x ++
+          "\n------------------ but got: -------------------\n" ++
+          y ++
+          "\n-----------------------------------------------"
+
+toDValueTest :: HUnit.Assertion
+toDValueTest = assertEqualString x y
+  where
+    x = "Right (DData \"Xyz\" (DConstructor \"Xyz\" [(Just \"xx\",Left (DInt 1)),(Just \"yy\",Left (DDouble 2.0)),(Just \"zz\",Left (DFloat 3.0)),(Just \"bb\",Right (DData \"(,,)\" (DConstructor \"(,,)\" [(Just \"(x,_,_)\",Right (DData \"Bool\" (DSum (DSimpleEnum [\"False\",\"True\"] 1)))),(Just \"(_,x,_)\",Right (DData \"Bool\" (DSum (DSimpleEnum [\"False\",\"True\"] 0)))),(Just \"(_,_,x)\",Right (DData \"Bool\" (DSum (DSimpleEnum [\"False\",\"True\"] 1))))]))),(Just \"ww\",Right (DData \"One\" (DConstructor \"MkOne\" [(Just \"one\",Left (DDouble 4.0))])))]))"
+
+    y = show (toDData (Xyz 1 2 3 (True, False, True) (MkOne 4)))
+
+updateDValueTest :: HUnit.Assertion
+updateDValueTest = assertEqualString' (fmap show x) (fmap show y)
+  where
+    x0 :: Xyz One
+    x0 = Xyz 1 2 3 (True, False, True) (MkOne 4)
+
+    dvalue =
+      DData "Xyz" $
+      DConstructor "Xyz" $
+      [ (Just "xx", Left (DInt 10))
+      , (Just "yy", Left (DDouble 20.0))
+      , (Just "zz", Left (DFloat 30.0))
+      , ( Just "bb"
+        , Right (DData "(,,)"
+                 (DConstructor "(,,)"
+                  [ (Just "(x,_,_)", Right (DData "Bool" (DSum (DSimpleEnum ["False", "True"] 0))))
+                  , (Just "(_,x,_)", Right (DData "Bool" (DSum (DSimpleEnum ["False", "True"] 1))))
+                  , (Just "(_,_,x)", Right (DData "Bool" (DSum (DSimpleEnum ["False", "True"] 1))))
+                  ]))
+        )
+      , (Just "ww", Right (DData "One"
+                           (DConstructor "MkOne"
+                            [ (Just "one", Left (DDouble 40.0))
+                            ])))
+      ]
+
+    x :: Either String (Xyz One)
+    x = Right $ Xyz 10 20 30 (False, True, True) (MkOne 40)
+
+    y :: Either String (Xyz One)
+    y = updateLookupable x0 (Right dvalue)
+
+badUpdateDValueTest :: HUnit.Assertion
+badUpdateDValueTest = assertEqualString' (fmap show x) (fmap show y)
+  where
+    x0 :: Xyz One
+    x0 = Xyz 1 2 3 (True, False, True) (MkOne 4)
+
+    dvalue =
+      DData "Xyz" $
+      DConstructor "Xyz" $
+      [ (Just "xx", Left (DInt 10))
+      , (Just "yy", Left (DDouble 20.0))
+      , (Just "zz", Left (DFloat 30.0))
+      , ( Just "b"
+        , Right (DData "(,,)"
+                 (DConstructor "(,,)"
+                  [ (Just "(x,_,_)", Right (DData "Bool" (DSum (DSimpleEnum ["False", "True"] 0))))
+                  , (Just "(_,x,_)", Right (DData "Bool" (DSum (DSimpleEnum ["False", "True"] 1))))
+                  , (Just "(_,_,x)", Right (DData "Bool" (DSum (DSimpleEnum ["False", "True"] 1))))
+                  ]))
+        )
+      , (Just "ww", Right (DData "One"
+                           (DConstructor "MkOne"
+                            [ (Just "one", Left (DDouble 40.0))
+                            ])))
+      ]
+
+    x :: Either String (Xyz One)
+    x = Left "accessor selector name Just \"bb\" doesn't match dynamic selector name Just \"b\""
+
+    y :: Either String (Xyz One)
+    y = updateLookupable x0 (Right dvalue)
+
 treeTest :: HUnit.Assertion
 treeTest = assertEqualString x y
   where
@@ -85,6 +183,11 @@
         , "        { xx = 6"
         , "        , yy = 7.00e0"
         , "        , zz = 8.00e0"
+        , "        , bb = (,,)"
+        , "               { (x,_,_) = True"
+        , "               , (_,x,_) = False"
+        , "               , (_,_,x) = False"
+        , "               }"
         , "        , ww = 9"
         , "        }"
         , ", lol = True"
@@ -93,10 +196,20 @@
         , "         { xx = 42"
         , "         , yy = 4.50e1"
         , "         , zz = 2.00e3"
+        , "         , bb = (,,)"
+        , "                { (x,_,_) = True"
+        , "                , (_,x,_) = True"
+        , "                , (_,_,x) = False"
+        , "                }"
         , "         , ww = Xyz"
         , "                { xx = 2"
         , "                , yy = 3.00e0"
         , "                , zz = 4.00e0"
+        , "                , bb = (,,)"
+        , "                       { (x,_,_) = False"
+        , "                       , (_,x,_) = True"
+        , "                       , (_,_,x) = False"
+        , "                       }"
         , "                , ww = 5.00e0"
         , "                }"
         , "         }"
@@ -115,15 +228,24 @@
         , "bbb.xx = 6"
         , "bbb.yy = 7.00e0"
         , "bbb.zz = 8.00e0"
+        , "bbb.bb.(x,_,_) = True"
+        , "bbb.bb.(_,x,_) = False"
+        , "bbb.bb.(_,_,x) = False"
         , "bbb.ww = 9"
         , "lol = True"
         , "notlol = False"
         , "yoyo.xx = 42"
         , "yoyo.yy = 4.50e1"
         , "yoyo.zz = 2.00e3"
+        , "yoyo.bb.(x,_,_) = True"
+        , "yoyo.bb.(_,x,_) = True"
+        , "yoyo.bb.(_,_,x) = False"
         , "yoyo.ww.xx = 2"
         , "yoyo.ww.yy = 3.00e0"
         , "yoyo.ww.zz = 4.00e0"
+        , "yoyo.ww.bb.(x,_,_) = False"
+        , "yoyo.ww.bb.(_,x,_) = True"
+        , "yoyo.ww.bb.(_,_,x) = False"
         , "yoyo.ww.ww = 5.00e0"
         , "ccc.one = 1.70e1"
         ]
@@ -133,20 +255,29 @@
 flatTestAligned = assertEqualString x y
   where
     x = init $ unlines
-        [ "aaa        = 2"
-        , "bbb.xx     = 6"
-        , "bbb.yy     = 7.00e0"
-        , "bbb.zz     = 8.00e0"
-        , "bbb.ww     = 9"
-        , "lol        = True"
-        , "notlol     = False"
-        , "yoyo.xx    = 42"
-        , "yoyo.yy    = 4.50e1"
-        , "yoyo.zz    = 2.00e3"
-        , "yoyo.ww.xx = 2"
-        , "yoyo.ww.yy = 3.00e0"
-        , "yoyo.ww.zz = 4.00e0"
-        , "yoyo.ww.ww = 5.00e0"
-        , "ccc.one    = 1.70e1"
+        [ "aaa                = 2"
+        , "bbb.xx             = 6"
+        , "bbb.yy             = 7.00e0"
+        , "bbb.zz             = 8.00e0"
+        , "bbb.bb.(x,_,_)     = True"
+        , "bbb.bb.(_,x,_)     = False"
+        , "bbb.bb.(_,_,x)     = False"
+        , "bbb.ww             = 9"
+        , "lol                = True"
+        , "notlol             = False"
+        , "yoyo.xx            = 42"
+        , "yoyo.yy            = 4.50e1"
+        , "yoyo.zz            = 2.00e3"
+        , "yoyo.bb.(x,_,_)    = True"
+        , "yoyo.bb.(_,x,_)    = True"
+        , "yoyo.bb.(_,_,x)    = False"
+        , "yoyo.ww.xx         = 2"
+        , "yoyo.ww.yy         = 3.00e0"
+        , "yoyo.ww.zz         = 4.00e0"
+        , "yoyo.ww.bb.(x,_,_) = False"
+        , "yoyo.ww.bb.(_,x,_) = True"
+        , "yoyo.ww.bb.(_,_,x) = False"
+        , "yoyo.ww.ww         = 5.00e0"
+        , "ccc.one            = 1.70e1"
         ]
     y = showFlat yup True (printf "%.2e") foo