diff --git a/byg/byg.cabal b/byg/byg.cabal
index 5bdb68b..44453ab 100644
--- a/byg/byg.cabal
+++ b/byg/byg.cabal
@@ -19,7 +19,8 @@ library
     exposed-modules:
         Types
         Sources
-        FunctionImplementations
+        FunctionImplementations.Pure
+        FunctionImplementations.IO
         ComputationM
         Functions
     build-depends:
diff --git a/byg/src/FunctionImplementations.hs b/byg/src/FunctionImplementations.hs
deleted file mode 100644
index dfe20cf..0000000
--- a/byg/src/FunctionImplementations.hs
+++ /dev/null
@@ -1,41 +0,0 @@
-module FunctionImplementations
-  ( IsImageFilename(..)
-  , ConvertedImageFilename(..)
-  , ListDirectory(..)
-  , OpenImage(..)
-  , ConvertImage(..)
-  , SaveFile(..)
-  , RunPandoc(..)
-  ) where
-
-import Sources()
-import Types
-
-data IsImageFilename = IsImageFilename deriving (Show)
-instance IsFunction IsImageFilename FilePath Bool where
-  runF IsImageFilename _path = undefined
-
-data ConvertedImageFilename = ConvertedImageFilename deriving (Show)
-instance IsFunction ConvertedImageFilename FilePath FilePath where
-  runF ConvertedImageFilename _path = undefined
-
-
-data ListDirectory = ListDirectory deriving (Show)
-instance IsFunctionIO ListDirectory FilePath [FilePath] where
-  runFIO ListDirectory _path = undefined
-
-data OpenImage = OpenImage deriving (Show)
-instance IsFunctionIO OpenImage FilePath Image where
-  runFIO OpenImage _path = undefined
-
-data ConvertImage = ConvertImage deriving (Show)
-instance IsFunctionIO ConvertImage Image Image where
-  runFIO ConvertImage _image = undefined
-
-data SaveFile = SaveFile deriving (Show)
-instance IsFunctionIO SaveFile (String, FilePath) () where
-  runFIO SaveFile _source = undefined
-
-data RunPandoc = RunPandoc deriving (Show)
-instance IsFunctionIO RunPandoc String String where
-  runFIO RunPandoc _source = undefined
diff --git a/byg/src/Functions.hs b/byg/src/Functions.hs
index 5107fdd..9aec2f8 100644
--- a/byg/src/Functions.hs
+++ b/byg/src/Functions.hs
@@ -9,7 +9,8 @@ module Functions
   , runPandoc
   ) where
 
-import FunctionImplementations
+import FunctionImplementations.Pure
+import FunctionImplementations.IO
 import ComputationM
 
 isImageFilename = runFunction IsImageFilename