so much less code needed!

src/Data/Language.hs

@@ -93,13 +93,3 @@ extensionsForLanguage language = case language of
 -- | Return a language based on a FilePath's extension, or Nothing if extension is not found or not supported.
 languageForFilePath :: FilePath -> Language
 languageForFilePath = languageForType . takeExtension
-
--- | Return the filename representing the prelude for the passed language, if any.
--- The convention here is "languagename.ext", lowercase. Note that this path
--- does not include the prelude directory, as that is configurable.
-preludeFilename :: Language -> Maybe FilePath
-preludeFilename l = case l of
-  Python     -> Just "python.py"
-  Ruby       -> Just "ruby.rb"
-  JavaScript -> Just "javascript.js"
-  _          -> Nothing

src/Data/Project.hs

@@ -15,7 +15,6 @@ module Data.Project (
   -- * Files
   , File (..)
   , file
-  , preludePath
   ) where
 
 import Prelude hiding (readFile)
@@ -113,6 +112,3 @@ readFile Project{..} f =
     | p == "/dev/null"  -> pure Nothing
     | isJust candidate  -> pure candidate
     | otherwise         -> throwError (SomeException (FileNotFound p))
-
-preludePath :: FilePath -> Language -> Maybe File
-preludePath dir lang = fmap (\p -> File (dir </> p) lang) (preludeFilename lang)