basic lazy generation of files

schpin_koke/src/Parser.hs

@@ -9,7 +9,7 @@ import           Control.Monad.State.Lazy
 import           Data.ByteString               as BS
                                                 ( readFile )
 import           Data.ByteString.Lazy          as BSL
-                                                ( writeFile )
+                                                ( writeFile, unpack )
 import qualified Data.Csv                      as CSV
 import           Data.Fixed                     ( mod' )
 import qualified Data.HashMap.Lazy             as HM
@@ -676,7 +676,7 @@ generateBOM walker pconf = do
     write_f (filebase, p) = do
         let filename = "out/bom/" ++ filebase ++ ".csv"
         createDirectoryIfMissing True $ takeDirectory filename
-        BSL.writeFile filename (CSV.encode $ parts_to_CSV p)
+        writeFileIfChanged filename (show $ BSL.unpack $ CSV.encode $ parts_to_CSV p)
 
     write_sum :: [ExtrPart] -> IO ()
     write_sum parts = do