diff --git a/byg/src/Functions.hs b/byg/src/Functions.hs
new file mode 100644
index 0000000..c49fbfa
--- /dev/null
+++ b/byg/src/Functions.hs
@@ -0,0 +1,22 @@
+{-# LANGUAGE GADTs #-}
+module Functions where
+
+data Image = Image
+  deriving (Show)
+data ImageConversion = ImageConversion
+  deriving (Show)
+
+data Function a b where
+  IsImageFilename :: Function FilePath Bool
+  ConvertedImageFilename :: Function FilePath FilePath
+
+deriving instance Show (Function a b)
+
+data FunctionIO a b where
+  ListDirectory :: FunctionIO FilePath [FilePath]
+  OpenImage :: FunctionIO FilePath Image
+  ConvertImage :: FunctionIO (Image, ImageConversion) Image
+  Save :: FunctionIO (a, FilePath) ()
+  RunPandoc :: FunctionIO String String
+
+deriving instance Show (FunctionIO a b)
diff --git a/byg/src/Main.hs b/byg/src/Main.hs
index b45db29..71d7466 100644
--- a/byg/src/Main.hs
+++ b/byg/src/Main.hs
@@ -11,28 +11,6 @@ data Source a where
   -- Void :: Source ()
   Data :: a -> Source a
 
-data Image = Image
-  deriving (Show)
-data ImageConversion = ImageConversion
-  deriving (Show)
-
-data Function a b where
-  IsImageFilename :: Function FilePath Bool
-  ConvertedImageFilename :: Function FilePath FilePath
-
-deriving instance Show (Function a b)
-
-data FunctionIO a b where
-  ListDirectory :: FunctionIO FilePath [FilePath]
-  OpenImage :: FunctionIO FilePath Image
-  ConvertImage :: FunctionIO (Image, ImageConversion) Image
-  Save :: FunctionIO (a, FilePath) ()
-  RunPandoc :: FunctionIO String String
-
-deriving instance Show (FunctionIO a b)
-
-
-
 
 -- data FlatComputation = Flat