Add Data.BLob.fileForRelPath and avoid early toString calls.

src/Data/Blob.hs

@@ -2,6 +2,7 @@
 module Data.Blob
 ( File(..)
 , fileForPath
+, fileForRelPath
 , Blob(..)
 , Blobs(..)
 , blobLanguage
@@ -32,6 +33,7 @@ import qualified Data.ByteString.Lazy as BL
 import           Data.JSON.Fields
 import           Data.Language
 import           Data.Source as Source
+import qualified System.Path as Path
 
 -- | A 'FilePath' paired with its corresponding 'Language'.
 -- Unpacked to have the same size overhead as (FilePath, Language).
@@ -40,9 +42,13 @@ data File = File
   , fileLanguage :: Language
   } deriving (Show, Eq, Generic)
 
+-- | Prefer 'fileForRelPath' if at all possible.
 fileForPath :: FilePath  -> File
 fileForPath p = File p (languageForFilePath p)
 
+fileForRelPath :: Path.RelFile -> File
+fileForRelPath = fileForPath . Path.toString
+
 -- | The source, path information, and language of a file read from disk.
 data Blob = Blob
   { blobSource   :: Source -- ^ The UTF-8 encoded source text of the blob.

test/Rendering/TOC/Spec.hs

@@ -220,7 +220,7 @@ isMethodOrFunction a
   | otherwise                                          = False
 
 blobsForPaths :: Both Path.RelFile -> IO BlobPair
-blobsForPaths = readFilePathPair . fmap Path.toString . fmap (Path.relDir "test/fixtures" </>)
+blobsForPaths = readFilePathPair . fmap (Path.relDir "test/fixtures" </>)
 
 blankDiff :: Diff'
 blankDiff = merge (Nothing, Nothing) (inject [ inserting (termIn Nothing (inject (Syntax.Identifier (name "\"a\"")))) ])

test/SpecHelpers.hs

@@ -88,20 +88,20 @@ instance IsString Name where
 -- | Returns an s-expression formatted diff for the specified FilePath pair.
 diffFilePaths :: TaskSession -> Both Path.RelFile -> IO ByteString
 diffFilePaths session paths
-  = readFilePathPair (fmap Path.toString paths)
+  = readFilePathPair paths
     >>= runTask session . parseDiffBuilder @[] DiffSExpression . pure
     >>= either (die . displayException) (pure . runBuilder)
 
 -- | Returns an s-expression parse tree for the specified path.
 parseFilePath :: TaskSession -> Path.RelFile -> IO (Either SomeException ByteString)
 parseFilePath session path = do
-  blob <- readBlobFromFile (fileForPath (Path.toString path))
+  blob <- readBlobFromFile (fileForRelPath path)
   res <- runTask session $ parseTermBuilder TermSExpression (toList blob)
   pure (runBuilder <$> res)
 
 -- | Read two files to a BlobPair.
-readFilePathPair :: Both FilePath -> IO BlobPair
-readFilePathPair paths = let paths' = fmap fileForPath paths in
+readFilePathPair :: Both Path.RelFile -> IO BlobPair
+readFilePathPair paths = let paths' = fmap fileForRelPath paths in
                      runBothWith readFilePair paths'
 
 parseTestFile :: Parser term -> Path.RelFile -> IO (Blob, term)