diff --git a/semantic-diff.cabal b/semantic-diff.cabal
index b90b6d02c..137f86a90 100644
--- a/semantic-diff.cabal
+++ b/semantic-diff.cabal
@@ -129,6 +129,7 @@ test-suite semantic-diff-test
                      , semantic-diff
                      , text >= 1.2.1.3
                      , these
+                     , vector
                      , wl-pprint-text
   if os(darwin)
     ghc-options:       -threaded -rtsopts -with-rtsopts=-N -j
diff --git a/src/Diffing.hs b/src/Diffing.hs
index 8fea49e8d..8bfab8c0f 100644
--- a/src/Diffing.hs
+++ b/src/Diffing.hs
@@ -6,11 +6,13 @@ import Prologue hiding (fst, snd)
 import qualified Data.ByteString.Char8 as B1
 import Data.Functor.Both
 import Data.Functor.Foldable
+import Data.RandomWalkSimilarity
 import Data.Record
 import qualified Data.Text.IO as TextIO
 import qualified Data.Text.ICU.Detect as Detect
 import qualified Data.Text.ICU.Convert as Convert
 import Data.These
+import qualified Data.Vector as Vector
 import Diff
 import Info
 import Interpreter
@@ -37,9 +39,9 @@ import qualified Data.Text as T
 -- | result.
 -- | Returns the rendered result strictly, so it's always fully evaluated
 -- | with respect to other IO actions.
-diffFiles :: (HasField fields Category, HasField fields Cost, HasField fields Range, Eq (Record fields)) => Parser (Syntax Text) (Record fields) -> Renderer (Record fields) -> Both SourceBlob -> IO Text
+diffFiles :: (HasField fields Category, HasField fields Cost, HasField fields Range, Eq (Record fields)) => Parser (Syntax Text) (Record fields) -> Renderer (Record (Vector.Vector Double ': fields)) -> Both SourceBlob -> IO Text
 diffFiles parser renderer sourceBlobs = do
-  terms <- traverse parser sourceBlobs
+  terms <- traverse (fmap (featureVectorDecorator getLabel p q d) . parser) sourceBlobs
 
   let areNullOids = runBothWith (\a b -> (oid a == nullOid || null (source a), oid b == nullOid || null (source b))) sourceBlobs
   let textDiff = case areNullOids of
@@ -55,6 +57,10 @@ diffFiles parser renderer sourceBlobs = do
         getCost diff = case runFree diff of
           Free (info :< _) -> cost <$> info
           Pure patch -> uncurry both (fromThese 0 0 (unPatch (cost . extract <$> patch)))
+        getLabel (h :< t) = (category h, case t of
+          Leaf s -> Just s
+          _ -> Nothing)
+        (p, q, d) = (2, 2, 15)
 
 -- | Return a parser based on the file extension (including the ".").
 parserForType :: Text -> Parser (Syntax Text) (Record '[Range, Category])
diff --git a/test/CorpusSpec.hs b/test/CorpusSpec.hs
index 5c39249d1..81207a038 100644
--- a/test/CorpusSpec.hs
+++ b/test/CorpusSpec.hs
@@ -1,6 +1,7 @@
 {-# LANGUAGE DataKinds, FlexibleContexts, GeneralizedNewtypeDeriving #-}
 module CorpusSpec where
 
+import qualified Data.Vector as Vector
 import Diffing
 import Renderer
 import qualified Renderer.JSON as J
@@ -69,7 +70,7 @@ normalizeName path = addExtension (dropExtension $ dropExtension path) (takeExte
 -- | Given file paths for A, B, and, optionally, a diff, return whether diffing
 -- | the files will produce the diff. If no diff is provided, then the result
 -- | is true, but the diff will still be calculated.
-testDiff :: Renderer (Record '[Cost, Range, Category]) -> Both FilePath -> Maybe FilePath -> (Verbatim -> Verbatim -> Expectation) -> Expectation
+testDiff :: Renderer (Record '[Vector.Vector Double, Cost, Range, Category]) -> Both FilePath -> Maybe FilePath -> (Verbatim -> Verbatim -> Expectation) -> Expectation
 testDiff renderer paths diff matcher = do
   sources <- sequence $ readAndTranscodeFile <$> paths
   actual <- Verbatim <$> diffFiles (decorateParser termCostDecorator parser) renderer (sourceBlobs sources)