Fix initialized variables for tensorflow 1.7 (#184)

* Fix initialized variables for tensorflow 1.7

This is needed to support tensorflow 1.7. The trick of initializing a
variable with `Shape []` and then overriding the shape by assigning an
initial value no longer works. It seems that we need to explicitly flip
the unknown_rank bit in the shape proto.

I thought about switching opgen to use `Maybe Shape` when an op requires
a shape attribute, but that will cause a lot of api churn, so I chose to
hold off for now and just do a spot fix to unblock 1.7.

tensorflow-ops/src/TensorFlow/Variable.hs

@@ -61,12 +61,21 @@ variable = variable' id
 
 variable' :: forall m a . (MonadBuild m, TensorType a)
                     => OpParams -> Shape -> m (Variable a)
-variable' params s = build $ do
+variable' params s = variableInternal params (Just s)
+
+variableInternal :: forall m a . (MonadBuild m, TensorType a)
+                 => OpParams -> Maybe Shape -> m (Variable a)
+variableInternal params s = build $ do
     -- Each variable needs a unique "shared_name".  Use MonadFix to
     -- set the attribute to the same name as the variable itself, without
     -- exposing more internals of the Build module.
-    rec t <- CoreOps.varHandleOp' (params . (opAttr "shared_name" .~ n))
+    rec let attrs = params . (opAttr "shared_name" .~ n) . (opAttr "shape" .~ s)
-                                    (tensorType (undefined :: a)) s
+            dtype = tensorType (undefined :: a)
+            -- Generated ops don't support unknown shapes. As a workaround, we
+            -- pass in a rank zero shape and then override it using OpParams.
+            -- TODO: Consider supporting this better in op generation.
+            shape = Shape []
+        t <- CoreOps.varHandleOp' attrs dtype shape
         let n = encodeUtf8 $ unNodeName $ tensorNodeName t
     return $ Variable t Nothing
 
@@ -80,7 +89,7 @@ initializedVariable' :: forall a m v . (MonadBuild m, TensorType a)
                     => OpParams -> Tensor v a -> m (Variable a)
 initializedVariable' params initializer = do
     -- The shape is not known initially.
-    (Variable h Nothing :: Variable a) <- variable' params (Shape [])
+    (Variable h Nothing :: Variable a) <- variableInternal params Nothing
     initializer' <- renderValue initializer
     i <- CoreOps.assignVariableOp h initializer'
     addInitializer =<< group i

tensorflow-ops/tests/VariableTest.hs

@@ -1,6 +1,7 @@
 {-# LANGUAGE OverloadedLists #-}
 module Main (main) where
 
+import Data.Int (Int32)
 import Data.Maybe (isJust)
 import Control.Monad (when)
 import Control.Monad.IO.Class (liftIO)
@@ -55,6 +56,8 @@ testInitializedVariableShape =
         vector <- initializedVariable (Ops.constant [1] [42 :: Float])
         result <- run (readValue vector)
         liftIO $ [42] @=? (result :: V.Vector Float)
+        s <- run (Ops.shape (readValue vector))
+        liftIO $ [1] @=? (s :: V.Vector Int32)
 
 testInitializedValue :: Test
 testInitializedValue =

tensorflow/src/TensorFlow/Types.hs

@@ -67,13 +67,15 @@ import Data.Functor.Identity (Identity(..))
 import Data.Complex (Complex)
 import Data.Default (def)
 import Data.Int (Int8, Int16, Int32, Int64)
+import Data.Maybe (fromMaybe)
 import Data.Monoid ((<>))
+import Data.ProtoLens.TextFormat (showMessageShort)
 import Data.Proxy (Proxy(..))
 import Data.String (IsString)
 import Data.Word (Word8, Word16, Word64)
 import Foreign.Storable (Storable)
 import GHC.Exts (Constraint, IsList(..))
-import Lens.Family2 (Lens', view, (&), (.~))
+import Lens.Family2 (Lens', view, (&), (.~), (^..))
 import Lens.Family2.Unchecked (iso)
 import Text.Printf (printf)
 import qualified Data.Attoparsec.ByteString as Atto
@@ -113,6 +115,7 @@ import Proto.Tensorflow.Core.Framework.TensorShape
     ( TensorShapeProto(..)
     , dim
     , size
+    , unknownRank
     )
 import Proto.Tensorflow.Core.Framework.Types (DataType(..))
 
@@ -353,6 +356,9 @@ headFromSingleton x
 
 
 -- | Shape (dimensions) of a tensor.
+--
+-- TensorFlow supports shapes of unknown rank, which are represented as
+-- @Nothing :: Maybe Shape@ in Haskell.
 newtype Shape = Shape [Int64] deriving Show
 
 instance IsList Shape where
@@ -363,8 +369,24 @@ instance IsList Shape where
 protoShape :: Lens' TensorShapeProto Shape
 protoShape = iso protoToShape shapeToProto
   where
-    protoToShape = Shape . fmap (view size) . view dim
+    protoToShape p = fromMaybe (error msg) (view protoMaybeShape p)
-    shapeToProto (Shape ds) = (def :: TensorShapeProto) & dim .~ fmap (\d -> def & size .~ d) ds
+      where msg = "Can't convert TensorShapeProto with unknown rank to Shape: "
+                  ++ showMessageShort p
+    shapeToProto s' = def & protoMaybeShape .~ Just s'
+
+protoMaybeShape :: Lens' TensorShapeProto (Maybe Shape)
+protoMaybeShape = iso protoToShape shapeToProto
+  where
+    protoToShape :: TensorShapeProto -> Maybe Shape
+    protoToShape p =
+        if view unknownRank p
+            then Nothing
+            else Just (Shape (p ^.. dim . traverse . size))
+    shapeToProto :: Maybe Shape -> TensorShapeProto
+    shapeToProto Nothing =
+        def & unknownRank .~ True
+    shapeToProto (Just (Shape ds)) =
+        def & dim .~ fmap (\d -> def & size .~ d) ds
 
 
 class Attribute a where
@@ -391,6 +413,9 @@ instance Attribute Bool where
 instance Attribute Shape where
     attrLens = shape . protoShape
 
+instance Attribute (Maybe Shape) where
+    attrLens = shape . protoMaybeShape
+
 -- TODO(gnezdo): support generating list(Foo) from [Foo].
 instance Attribute AttrValue'ListValue where
     attrLens = list