diff --git a/byg/src/Main.hs b/byg/src/Main.hs
index 6895dbf..046d887 100644
--- a/byg/src/Main.hs
+++ b/byg/src/Main.hs
@@ -6,11 +6,6 @@ module Main where
 import Unsafe.Coerce (unsafeCoerce)
 import Control.Monad.State
 import Control.Monad.Writer
-import Data.ByteString (ByteString)
-
-data Source a where
-  -- Void :: Source ()
-  Data :: a -> Source a
 
 
 -- data FlatComputation = Flat
@@ -27,16 +22,6 @@ data Source a where
 data ComputationRun a b = ComputationRun (Function a b)
                         | ComputationRunIO (FunctionIO a b)
 
-class SourceState a where
-  stateOfSource :: a -> IO ByteString
-  -- makeChecker :: a -> IO (a -> Bool)
-
-instance SourceState FilePath where
-  stateOfSource = undefined
-  -- makeChecker = undefined
-
-class SourceState a => IsFIO f a b | f -> a b where
-  runFIO :: f -> a -> IO b
 
 data ListDirectory' = ListDirectory'
 instance IsFIO ListDirectory' FilePath [FilePath] where
@@ -80,11 +65,6 @@ data Dependency ta a tb b = Dependency (Token ta a) (TypedRun a b) (Token tb b)
 data DependencyUntyped where
   DependencyUntyped :: Dependency ta a tb b -> String -> DependencyUntyped
 
---deriving instance Show DependencyUntyped
-
--- showDU :: DependencyUntyped -> String
--- showDU (DependencyUntyped d) = show d
-
 instance Show DependencyUntyped where
   show (DependencyUntyped _ s) = s
 
diff --git a/byg/src/Sources.hs b/byg/src/Sources.hs
new file mode 100644
index 0000000..3bd7de7
--- /dev/null
+++ b/byg/src/Sources.hs
@@ -0,0 +1,16 @@
+{-# LANGUAGE FunctionalDependencies #-}
+module Sources where
+
+import Data.ByteString (ByteString)
+
+data Source a where
+  Data :: a -> Source a
+
+class SourceState a where
+  stateOfSource :: a -> IO ByteString
+
+instance SourceState FilePath where
+  stateOfSource = undefined
+
+class SourceState a => IsFIO f a b | f -> a b where
+  runFIO :: f -> a -> IO b