From 4b046e6f4e917465b3e19abb2069c2791a0ca74f Mon Sep 17 00:00:00 2001
From: joshvera <vera@github.com>
Date: Mon, 28 Mar 2016 13:31:10 -0400
Subject: [PATCH 01/13] Return IO Text from printDiff

---
 src/DiffOutput.hs     | 17 ++++++++++++-----
 src/Renderer/JSON.hs  | 14 ++++++--------
 src/Renderer/Patch.hs |  5 +++--
 src/Renderer/Split.hs |  5 +++--
 4 files changed, 24 insertions(+), 17 deletions(-)

diff --git a/src/DiffOutput.hs b/src/DiffOutput.hs
index 6fd0bb386..277d1c0ba 100644
--- a/src/DiffOutput.hs
+++ b/src/DiffOutput.hs
@@ -1,7 +1,6 @@
 module DiffOutput where
 
-import qualified Data.ByteString.Lazy as B
-import qualified Data.Text.Lazy.IO as TextIO
+import qualified Data.Text.IO as TextIO
 import Data.Functor.Both
 import Diffing
 import Parser
@@ -12,6 +11,8 @@ import Source
 import System.Directory
 import System.FilePath
 import qualified System.IO as IO
+import Data.String
+import Data.Text hiding (split)
 
 -- | The available types of diff rendering.
 data Format = Split | Patch | JSON
@@ -19,8 +20,14 @@ data Format = Split | Patch | JSON
 data DiffArguments = DiffArguments { format :: Format, output :: Maybe FilePath, outputPath :: FilePath }
 
 -- | Return a renderer from the command-line arguments that will print the diff.
-printDiff :: Parser -> DiffArguments -> Both SourceBlob -> IO ()
+printDiff :: Parser -> DiffArguments -> Both SourceBlob -> IO Text
 printDiff parser arguments sources = case format arguments of
+  Split -> diffFiles parser split sources
+  Patch -> diffFiles parser P.patch sources
+  JSON -> diffFiles parser J.json sources
+
+printDiff' :: Parser -> DiffArguments -> Both SourceBlob -> IO ()
+printDiff' parser arguments sources = case format arguments of
   Split -> put (output arguments) =<< diffFiles parser split sources
     where
       put Nothing rendered = TextIO.putStr rendered
@@ -30,5 +37,5 @@ printDiff parser arguments sources = case format arguments of
                          then path </> (takeFileName outputPath -<.> ".html")
                          else path
         IO.withFile outputPath IO.WriteMode (`TextIO.hPutStr` rendered)
-  Patch -> putStr =<< diffFiles parser P.patch sources
-  JSON -> B.putStr =<< diffFiles parser J.json sources
+  Patch -> TextIO.putStr =<< diffFiles parser P.patch sources
+  JSON -> TextIO.putStr =<< diffFiles parser J.json sources
diff --git a/src/Renderer/JSON.hs b/src/Renderer/JSON.hs
index 496d838c3..01d2ea98a 100644
--- a/src/Renderer/JSON.hs
+++ b/src/Renderer/JSON.hs
@@ -9,11 +9,12 @@ import Category
 import Control.Comonad.Cofree
 import Control.Monad.Free
 import Data.Aeson hiding (json)
-import Data.ByteString.Builder
-import Data.ByteString.Lazy
+import Data.Aeson.Encode
 import Data.Functor.Both
-import Data.Monoid
 import Data.OrderedMap hiding (fromList)
+import Data.Text
+import Data.Text.Lazy (toStrict)
+import Data.Text.Lazy.Builder (toLazyText)
 import qualified Data.Text as T
 import Data.Vector hiding (toList)
 import Diff
@@ -26,11 +27,8 @@ import Syntax
 import Term
 
 -- | Render a diff to a string representing its JSON.
-json :: Renderer a ByteString
-json diff sources = toLazyByteString . fromEncoding . pairs $
-     "rows" .= annotateRows (splitDiffByLines (source <$> sources) diff)
-  <> "oids" .= (oid <$> sources)
-  <> "paths" .= (path <$> sources)
+json :: Renderer a Text
+json diff sources = toStrict . toLazyText . encodeToTextBuilder $ object ["rows" .= annotateRows (splitDiffByLines (source <$> sources) diff), "oids" .= (oid <$> sources), "paths" .= (path <$> sources)]
   where annotateRows = fmap (fmap NumberedLine) . numberedRows
 
 newtype NumberedLine a = NumberedLine (Int, Line a)
diff --git a/src/Renderer/Patch.hs b/src/Renderer/Patch.hs
index a41d831be..8ef23b497 100644
--- a/src/Renderer/Patch.hs
+++ b/src/Renderer/Patch.hs
@@ -19,10 +19,11 @@ import Data.Functor.Both as Both
 import Data.List
 import Data.Maybe
 import Data.Monoid
+import Data.Text (pack, Text)
 
 -- | Render a diff in the traditional patch format.
-patch :: Renderer a String
-patch diff sources = case getLast $ foldMap (Last . Just) string of
+patch :: Renderer a Text
+patch diff sources = pack $ case getLast (foldMap (Last . Just) string) of
   Just c | c /= '\n' -> string ++ "\n\\ No newline at end of file\n"
   _ -> string
   where string = mconcat $ showHunk sources <$> hunks diff sources
diff --git a/src/Renderer/Split.hs b/src/Renderer/Split.hs
index c899de5ec..451d5d01a 100644
--- a/src/Renderer/Split.hs
+++ b/src/Renderer/Split.hs
@@ -8,6 +8,7 @@ import Control.Monad.Free
 import Data.Foldable
 import Data.Functor.Both
 import Data.Monoid
+import qualified Data.Text as T
 import qualified Data.Text.Lazy as TL
 import Diff
 import Line
@@ -51,8 +52,8 @@ splitPatchToClassName patch = stringValue $ "patch " ++ case patch of
   SplitReplace _ -> "replace"
 
 -- | Render a diff as an HTML split diff.
-split :: Renderer leaf TL.Text
-split diff blobs = renderHtml
+split :: Renderer leaf T.Text
+split diff blobs = TL.toStrict . renderHtml
   . docTypeHtml
     . ((head $ link ! A.rel "stylesheet" ! A.href "style.css") <>)
     . body

From 7947bc1911781af46836a5700105fa17a2ce7d43 Mon Sep 17 00:00:00 2001
From: joshvera <vera@github.com>
Date: Fri, 1 Apr 2016 15:34:52 -0400
Subject: [PATCH 02/13] Move DiffArguments to Renderer.hs

---
 src/DiffOutput.hs | 6 +-----
 src/Renderer.hs   | 5 +++++
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/src/DiffOutput.hs b/src/DiffOutput.hs
index 277d1c0ba..0fa5ef6ae 100644
--- a/src/DiffOutput.hs
+++ b/src/DiffOutput.hs
@@ -6,6 +6,7 @@ import Diffing
 import Parser
 import qualified Renderer.JSON as J
 import qualified Renderer.Patch as P
+import Renderer
 import Renderer.Split
 import Source
 import System.Directory
@@ -14,11 +15,6 @@ import qualified System.IO as IO
 import Data.String
 import Data.Text hiding (split)
 
--- | The available types of diff rendering.
-data Format = Split | Patch | JSON
-
-data DiffArguments = DiffArguments { format :: Format, output :: Maybe FilePath, outputPath :: FilePath }
-
 -- | Return a renderer from the command-line arguments that will print the diff.
 printDiff :: Parser -> DiffArguments -> Both SourceBlob -> IO Text
 printDiff parser arguments sources = case format arguments of
diff --git a/src/Renderer.hs b/src/Renderer.hs
index ea381c406..35f1f5f43 100644
--- a/src/Renderer.hs
+++ b/src/Renderer.hs
@@ -7,3 +7,8 @@ import Source
 
 -- | A function that will render a diff, given the two source files.
 type Renderer a b = Diff a Info -> Both SourceBlob -> b
+
+data DiffArguments = DiffArguments { format :: Format, output :: Maybe FilePath, outputPath :: FilePath }
+
+-- | The available types of diff rendering.
+data Format = Split | Patch | JSON

From a18c2649d37881feac9f928a91decbe985d9af51 Mon Sep 17 00:00:00 2001
From: joshvera <vera@github.com>
Date: Fri, 1 Apr 2016 15:35:09 -0400
Subject: [PATCH 03/13] Add a truncatePatch function

---
 src/DiffOutput.hs     | 6 ++++++
 src/Renderer/Patch.hs | 7 ++++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/DiffOutput.hs b/src/DiffOutput.hs
index 0fa5ef6ae..3d0a8fc93 100644
--- a/src/DiffOutput.hs
+++ b/src/DiffOutput.hs
@@ -22,6 +22,12 @@ printDiff parser arguments sources = case format arguments of
   Patch -> diffFiles parser P.patch sources
   JSON -> diffFiles parser J.json sources
 
+truncatedDiff :: DiffArguments -> Both SourceBlob -> IO Text
+truncatedDiff arguments sources = case format arguments of
+  Split -> return ""
+  Patch -> return $ P.truncatePatch arguments sources
+  JSON -> return "{}"
+
 printDiff' :: Parser -> DiffArguments -> Both SourceBlob -> IO ()
 printDiff' parser arguments sources = case format arguments of
   Split -> put (output arguments) =<< diffFiles parser split sources
diff --git a/src/Renderer/Patch.hs b/src/Renderer/Patch.hs
index cf226dcfa..93c64ffba 100644
--- a/src/Renderer/Patch.hs
+++ b/src/Renderer/Patch.hs
@@ -1,7 +1,8 @@
 module Renderer.Patch (
   patch,
   hunks,
-  Hunk(..)
+  Hunk(..),
+  truncatePatch
 ) where
 
 import Alignment
@@ -22,6 +23,10 @@ import Data.Maybe
 import Data.Monoid
 import Data.Text (pack, Text)
 
+-- | Render a timed out file as a truncated diff.
+truncatePatch :: DiffArguments -> Both SourceBlob -> Text
+truncatePatch arguments blobs = pack $ header blobs ++ "#timed_out\nTruncating diff: timeout reached.\n"
+
 -- | Render a diff in the traditional patch format.
 patch :: Renderer a Text
 patch diff blobs = pack $ case getLast (foldMap (Last . Just) string) of

From 842a0f30afc79ce97265f3dc39ca0dfc73c78d60 Mon Sep 17 00:00:00 2001
From: joshvera <vera@github.com>
Date: Fri, 1 Apr 2016 15:35:21 -0400
Subject: [PATCH 04/13] Move emptyHunk to a function

---
 src/Renderer/Patch.hs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/Renderer/Patch.hs b/src/Renderer/Patch.hs
index 93c64ffba..6cba19849 100644
--- a/src/Renderer/Patch.hs
+++ b/src/Renderer/Patch.hs
@@ -113,13 +113,16 @@ header blobs = intercalate "\n" [filepathHeader, fileModeHeader, beforeFilepath,
         (oidA, oidB) = runBoth $ oid <$> blobs
         (modeA, modeB) = runBoth $ blobKind <$> blobs
 
+emptyHunk :: Hunk (SplitDiff a Info)
+emptyHunk = Hunk { offset = mempty, changes = [], trailingContext = [] }
+
 -- | Render a diff as a series of hunks.
 hunks :: Renderer a [Hunk (SplitDiff a Info)]
 hunks _ blobs | sources <- source <$> blobs
               , sourcesEqual <- runBothWith (==) sources
               , sourcesNull <- runBothWith (&&) (null <$> sources)
               , sourcesEqual || sourcesNull
-  = [Hunk { offset = mempty, changes = [], trailingContext = [] }]
+  = [emptyHunk]
 hunks diff blobs = hunksInRows (Both (1, 1)) $ fmap (fmap Prelude.fst) <$> splitDiffByLines (source <$> blobs) diff
 
 -- | Given beginning line numbers, turn rows in a split diff into hunks in a

From cf898c66c64260f055e3c254b788b46c571e9ee4 Mon Sep 17 00:00:00 2001
From: joshvera <vera@github.com>
Date: Fri, 1 Apr 2016 15:35:38 -0400
Subject: [PATCH 05/13] Strictly render in diffFiles

---
 src/Diffing.hs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Diffing.hs b/src/Diffing.hs
index 63730807b..619a94fcd 100644
--- a/src/Diffing.hs
+++ b/src/Diffing.hs
@@ -75,4 +75,4 @@ diffFiles parser renderer sourceBlobs = do
   let sources = source <$> sourceBlobs
   terms <- sequence $ parser <$> sources
   let replaceLeaves = breakDownLeavesByWord <$> sources
-  return $ renderer (runBothWith diffTerms $ replaceLeaves <*> terms) sourceBlobs
+  return $! renderer (runBothWith diffTerms $ replaceLeaves <*> terms) sourceBlobs

From 4a7004394b21f43d5e79c58dee65e403975a9809 Mon Sep 17 00:00:00 2001
From: joshvera <vera@github.com>
Date: Fri, 1 Apr 2016 15:53:16 -0400
Subject: [PATCH 06/13] fix tests

---
 test/CorpusSpec.hs | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/test/CorpusSpec.hs b/test/CorpusSpec.hs
index 70bd559df..7dcf0a298 100644
--- a/test/CorpusSpec.hs
+++ b/test/CorpusSpec.hs
@@ -44,11 +44,13 @@ spec = parallel $ do
     correctTests paths@(_, Nothing, Nothing, Nothing) = testsForPaths paths
     correctTests paths = List.filter (\(_, _, _, output) -> isJust output) $ testsForPaths paths
     testsForPaths :: (Both FilePath, Maybe FilePath, Maybe FilePath, Maybe FilePath) -> [(String, Renderer a String, Both FilePath, Maybe FilePath)]
-    testsForPaths (paths, json, patch, split) = [ ("json", testJSON, paths, json), ("patch", P.patch, paths, patch), ("split", testSplit, paths, split) ]
+    testsForPaths (paths, json, patch, split) = [ ("json", testJSON, paths, json), ("patch", testPatch, paths, patch), ("split", testSplit, paths, split) ]
+    testPatch :: Renderer a String
+    testPatch diff sources = T.unpack $ P.patch diff sources
     testSplit :: Renderer a String
-    testSplit diff sources = TL.unpack $ Split.split diff sources
+    testSplit diff sources = T.unpack $ Split.split diff sources
     testJSON :: Renderer a String
-    testJSON diff sources = B.unpack $ J.json diff sources
+    testJSON diff sources = T.unpack $ J.json diff sources
 
 
 -- | Return all the examples from the given directory. Examples are expected to

From 4512344e3aa6b180f55f6809477cae743c6bc913 Mon Sep 17 00:00:00 2001
From: joshvera <vera@github.com>
Date: Fri, 1 Apr 2016 16:07:05 -0400
Subject: [PATCH 07/13] update dictionary.json.js

---
 test/diffs/dictionary.json.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/diffs/dictionary.json.js b/test/diffs/dictionary.json.js
index 0fd2f4ee8..fe957e0cc 100644
--- a/test/diffs/dictionary.json.js
+++ b/test/diffs/dictionary.json.js
@@ -1 +1 @@
-{"rows":[[{"number":1,"terms":[{"range":[0,2],"categories":["program"],"children":[{"range":[0,2],"categories":["expression_statement"],"children":[{"range":[0,2],"categories":["DictionaryLiteral"],"children":{}}]}]}],"range":[0,2],"hasChanges":false},{"number":1,"terms":[{"range":[0,2],"categories":["program"],"children":[{"range":[0,2],"categories":["expression_statement"],"children":[{"range":[0,2],"categories":["DictionaryLiteral"],"children":{}}]}]}],"range":[0,2],"hasChanges":false}],[{"number":2,"terms":[{"range":[2,12],"categories":["program"],"children":[{"range":[2,12],"categories":["expression_statement"],"children":[{"range":[2,12],"categories":["DictionaryLiteral"],"children":{"\"b\"":{"range":[4,10],"categories":["Pair"],"children":[{"range":[4,7],"categories":["StringLiteral"],"children":[{"range":[4,5],"categories":["StringLiteral"]},{"range":[5,6],"categories":["StringLiteral"]},{"range":[6,7],"categories":["StringLiteral"]}]},{"patch":"replace","range":[9,10],"categories":["number"]}]}}}]}]}],"range":[2,12],"hasChanges":true},{"number":2,"terms":[{"range":[2,12],"categories":["program"],"children":[{"range":[2,12],"categories":["expression_statement"],"children":[{"range":[2,12],"categories":["DictionaryLiteral"],"children":{"\"b\"":{"range":[4,10],"categories":["Pair"],"children":[{"range":[4,7],"categories":["StringLiteral"],"children":[{"range":[4,5],"categories":["StringLiteral"]},{"range":[5,6],"categories":["StringLiteral"]},{"range":[6,7],"categories":["StringLiteral"]}]},{"patch":"replace","range":[9,10],"categories":["number"]}]}}}]}]}],"range":[2,12],"hasChanges":true}],[{"number":3,"terms":[{"range":[12,21],"categories":["program"],"children":[{"range":[12,21],"categories":["expression_statement"],"children":[{"range":[12,21],"categories":["DictionaryLiteral"],"children":{"\"a\"":{"range":[14,20],"categories":["Pair"],"children":[{"range":[14,17],"categories":["StringLiteral"],"children":[{"range":[14,15],"categories":["StringLiteral"]},{"range":[15,16],"categories":["StringLiteral"]},{"range":[16,17],"categories":["StringLiteral"]}]},{"range":[19,20],"categories":["number"]}]}}}]}]}],"range":[12,21],"hasChanges":false},{"number":3,"terms":[{"range":[12,21],"categories":["program"],"children":[{"range":[12,21],"categories":["expression_statement"],"children":[{"range":[12,21],"categories":["DictionaryLiteral"],"children":{"\"a\"":{"range":[14,20],"categories":["Pair"],"children":[{"range":[14,17],"categories":["StringLiteral"],"children":[{"range":[14,15],"categories":["StringLiteral"]},{"range":[15,16],"categories":["StringLiteral"]},{"range":[16,17],"categories":["StringLiteral"]}]},{"range":[19,20],"categories":["number"]}]}}}]}]}],"range":[12,21],"hasChanges":false}],[{"number":4,"terms":[{"range":[21,23],"categories":["program"],"children":[{"range":[21,23],"categories":["expression_statement"],"children":[{"range":[21,22],"categories":["DictionaryLiteral"],"children":{}}]}]}],"range":[21,23],"hasChanges":false},{"number":4,"terms":[{"range":[21,23],"categories":["program"],"children":[{"range":[21,23],"categories":["expression_statement"],"children":[{"range":[21,22],"categories":["DictionaryLiteral"],"children":{}}]}]}],"range":[21,23],"hasChanges":false}],[{"number":5,"terms":[{"range":[23,23],"categories":["program"],"children":[{"range":[23,23],"categories":["expression_statement"],"children":[]}]}],"range":[23,23],"hasChanges":false},{"number":5,"terms":[{"range":[23,23],"categories":["program"],"children":[{"range":[23,23],"categories":["expression_statement"],"children":[]}]}],"range":[23,23],"hasChanges":false}]],"oids":["",""],"paths":["test/diffs/dictionary.A.js","test/diffs/dictionary.B.js"]}
\ No newline at end of file
+{"rows":[[{"terms":[{"children":[{"children":[{"children":{},"categories":["DictionaryLiteral"],"range":[0,2]}],"categories":["expression_statement"],"range":[0,2]}],"categories":["program"],"range":[0,2]}],"hasChanges":false,"range":[0,2],"number":1},{"terms":[{"children":[{"children":[{"children":{},"categories":["DictionaryLiteral"],"range":[0,2]}],"categories":["expression_statement"],"range":[0,2]}],"categories":["program"],"range":[0,2]}],"hasChanges":false,"range":[0,2],"number":1}],[{"terms":[{"children":[{"children":[{"children":{"\"b\"":{"children":[{"children":[{"categories":["StringLiteral"],"range":[4,5]},{"categories":["StringLiteral"],"range":[5,6]},{"categories":["StringLiteral"],"range":[6,7]}],"categories":["StringLiteral"],"range":[4,7]},{"patch":"replace","categories":["number"],"range":[9,10]}],"categories":["Pair"],"range":[4,10]}},"categories":["DictionaryLiteral"],"range":[2,12]}],"categories":["expression_statement"],"range":[2,12]}],"categories":["program"],"range":[2,12]}],"hasChanges":true,"range":[2,12],"number":2},{"terms":[{"children":[{"children":[{"children":{"\"b\"":{"children":[{"children":[{"categories":["StringLiteral"],"range":[4,5]},{"categories":["StringLiteral"],"range":[5,6]},{"categories":["StringLiteral"],"range":[6,7]}],"categories":["StringLiteral"],"range":[4,7]},{"patch":"replace","categories":["number"],"range":[9,10]}],"categories":["Pair"],"range":[4,10]}},"categories":["DictionaryLiteral"],"range":[2,12]}],"categories":["expression_statement"],"range":[2,12]}],"categories":["program"],"range":[2,12]}],"hasChanges":true,"range":[2,12],"number":2}],[{"terms":[{"children":[{"children":[{"children":{"\"a\"":{"children":[{"children":[{"categories":["StringLiteral"],"range":[14,15]},{"categories":["StringLiteral"],"range":[15,16]},{"categories":["StringLiteral"],"range":[16,17]}],"categories":["StringLiteral"],"range":[14,17]},{"categories":["number"],"range":[19,20]}],"categories":["Pair"],"range":[14,20]}},"categories":["DictionaryLiteral"],"range":[12,21]}],"categories":["expression_statement"],"range":[12,21]}],"categories":["program"],"range":[12,21]}],"hasChanges":false,"range":[12,21],"number":3},{"terms":[{"children":[{"children":[{"children":{"\"a\"":{"children":[{"children":[{"categories":["StringLiteral"],"range":[14,15]},{"categories":["StringLiteral"],"range":[15,16]},{"categories":["StringLiteral"],"range":[16,17]}],"categories":["StringLiteral"],"range":[14,17]},{"categories":["number"],"range":[19,20]}],"categories":["Pair"],"range":[14,20]}},"categories":["DictionaryLiteral"],"range":[12,21]}],"categories":["expression_statement"],"range":[12,21]}],"categories":["program"],"range":[12,21]}],"hasChanges":false,"range":[12,21],"number":3}],[{"terms":[{"children":[{"children":[{"children":{},"categories":["DictionaryLiteral"],"range":[21,22]}],"categories":["expression_statement"],"range":[21,23]}],"categories":["program"],"range":[21,23]}],"hasChanges":false,"range":[21,23],"number":4},{"terms":[{"children":[{"children":[{"children":{},"categories":["DictionaryLiteral"],"range":[21,22]}],"categories":["expression_statement"],"range":[21,23]}],"categories":["program"],"range":[21,23]}],"hasChanges":false,"range":[21,23],"number":4}],[{"terms":[{"children":[{"children":[],"categories":["expression_statement"],"range":[23,23]}],"categories":["program"],"range":[23,23]}],"hasChanges":false,"range":[23,23],"number":5},{"terms":[{"children":[{"children":[],"categories":["expression_statement"],"range":[23,23]}],"categories":["program"],"range":[23,23]}],"hasChanges":false,"range":[23,23],"number":5}]],"paths":["test/diffs/dictionary.A.js","test/diffs/dictionary.B.js"],"oids":["",""]}
\ No newline at end of file

From ba8fef376ae37491a7ee732193c63bb01fa8cc81 Mon Sep 17 00:00:00 2001
From: joshvera <vera@github.com>
Date: Sat, 2 Apr 2016 13:28:17 -0400
Subject: [PATCH 08/13] move to where clause

---
 test/CorpusSpec.hs | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/test/CorpusSpec.hs b/test/CorpusSpec.hs
index 7dcf0a298..cd1bb688f 100644
--- a/test/CorpusSpec.hs
+++ b/test/CorpusSpec.hs
@@ -79,12 +79,16 @@ normalizeName path = addExtension (dropExtension $ dropExtension path) (takeExte
 -- | is true, but the diff will still be calculated.
 testDiff :: Renderer T.Text String -> Both FilePath -> Maybe FilePath -> (String -> String -> Expectation) -> Expectation
 testDiff renderer paths diff matcher = do
-  let parser = parserForFilepath (fst paths)
   sources <- sequence $ readAndTranscodeFile <$> paths
-  let sourceBlobs = Both (S.SourceBlob, S.SourceBlob) <*> sources <*> pure mempty <*> paths <*> pure (Just S.defaultPlainBlob)
   actual <- diffFiles parser renderer sourceBlobs
   case diff of
     Nothing -> matcher actual actual
     Just file -> do
       expected <- readFile file
       matcher actual expected
+  where parser = parserForFilepath (fst paths)
+        sourceBlobs = Both (S.SourceBlob, S.SourceBlob) <*>
+          sources <*>
+          pure mempty <*>
+          paths <*>
+          pure (Just S.defaultPlainBlob)

From 506abacbc68e2e25f9eca62e80433b17be0101a7 Mon Sep 17 00:00:00 2001
From: joshvera <vera@github.com>
Date: Mon, 4 Apr 2016 17:03:35 -0400
Subject: [PATCH 09/13] Document use of strictness in diffFiles

---
 src/Diffing.hs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/Diffing.hs b/src/Diffing.hs
index 619a94fcd..6e9fd0e69 100644
--- a/src/Diffing.hs
+++ b/src/Diffing.hs
@@ -70,6 +70,8 @@ readAndTranscodeFile path = do
 
 -- | Given a parser and renderer, diff two sources and return the rendered
 -- | result.
+-- | Returns the rendered result strictly, so it's always fully evaluated
+-- | with respect to other IO actions.
 diffFiles :: Parser -> Renderer T.Text b -> Both SourceBlob -> IO b
 diffFiles parser renderer sourceBlobs = do
   let sources = source <$> sourceBlobs

From 90013b1235fc6361b11c1951fe443f604f665de2 Mon Sep 17 00:00:00 2001
From: joshvera <vera@github.com>
Date: Mon, 4 Apr 2016 17:08:29 -0400
Subject: [PATCH 10/13] Rename printDiff to textDiff and printDiff' to
 printDiff

---
 src/DiffOutput.hs | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/DiffOutput.hs b/src/DiffOutput.hs
index 3d0a8fc93..cd6f09acb 100644
--- a/src/DiffOutput.hs
+++ b/src/DiffOutput.hs
@@ -16,8 +16,8 @@ import Data.String
 import Data.Text hiding (split)
 
 -- | Return a renderer from the command-line arguments that will print the diff.
-printDiff :: Parser -> DiffArguments -> Both SourceBlob -> IO Text
-printDiff parser arguments sources = case format arguments of
+textDiff :: Parser -> DiffArguments -> Both SourceBlob -> IO Text
+textDiff parser arguments sources = case format arguments of
   Split -> diffFiles parser split sources
   Patch -> diffFiles parser P.patch sources
   JSON -> diffFiles parser J.json sources
@@ -28,8 +28,8 @@ truncatedDiff arguments sources = case format arguments of
   Patch -> return $ P.truncatePatch arguments sources
   JSON -> return "{}"
 
-printDiff' :: Parser -> DiffArguments -> Both SourceBlob -> IO ()
-printDiff' parser arguments sources = case format arguments of
+printDiff :: Parser -> DiffArguments -> Both SourceBlob -> IO ()
+printDiff parser arguments sources = case format arguments of
   Split -> put (output arguments) =<< diffFiles parser split sources
     where
       put Nothing rendered = TextIO.putStr rendered

From 3b752b834cdcaa435cfdadcf390a172ba8df9fef Mon Sep 17 00:00:00 2001
From: joshvera <vera@github.com>
Date: Mon, 4 Apr 2016 17:12:02 -0400
Subject: [PATCH 11/13] docs

---
 src/DiffOutput.hs     | 4 +++-
 src/Renderer/Patch.hs | 1 +
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/DiffOutput.hs b/src/DiffOutput.hs
index cd6f09acb..8516a0ee9 100644
--- a/src/DiffOutput.hs
+++ b/src/DiffOutput.hs
@@ -15,19 +15,21 @@ import qualified System.IO as IO
 import Data.String
 import Data.Text hiding (split)
 
--- | Return a renderer from the command-line arguments that will print the diff.
+-- | Returns a rendered diff given a parser, diff arguments and two source blobs.
 textDiff :: Parser -> DiffArguments -> Both SourceBlob -> IO Text
 textDiff parser arguments sources = case format arguments of
   Split -> diffFiles parser split sources
   Patch -> diffFiles parser P.patch sources
   JSON -> diffFiles parser J.json sources
 
+-- | Returns a truncated diff given diff arguments and two source blobs.
 truncatedDiff :: DiffArguments -> Both SourceBlob -> IO Text
 truncatedDiff arguments sources = case format arguments of
   Split -> return ""
   Patch -> return $ P.truncatePatch arguments sources
   JSON -> return "{}"
 
+-- | Prints a rendered diff to stdio or a filepath given a parser, diff arguments and two source blobs.
 printDiff :: Parser -> DiffArguments -> Both SourceBlob -> IO ()
 printDiff parser arguments sources = case format arguments of
   Split -> put (output arguments) =<< diffFiles parser split sources
diff --git a/src/Renderer/Patch.hs b/src/Renderer/Patch.hs
index 6cba19849..44a7ebc7d 100644
--- a/src/Renderer/Patch.hs
+++ b/src/Renderer/Patch.hs
@@ -113,6 +113,7 @@ header blobs = intercalate "\n" [filepathHeader, fileModeHeader, beforeFilepath,
         (oidA, oidB) = runBoth $ oid <$> blobs
         (modeA, modeB) = runBoth $ blobKind <$> blobs
 
+-- | A hunk representing no changes.
 emptyHunk :: Hunk (SplitDiff a Info)
 emptyHunk = Hunk { offset = mempty, changes = [], trailingContext = [] }
 

From a5537091125ba408d2d6d908d33e9d84aafff1f6 Mon Sep 17 00:00:00 2001
From: joshvera <vera@github.com>
Date: Mon, 4 Apr 2016 17:20:26 -0400
Subject: [PATCH 12/13] Specialize Renderer to Text

---
 src/Diffing.hs        |  2 +-
 src/Renderer.hs       |  3 ++-
 src/Renderer/JSON.hs  |  2 +-
 src/Renderer/Patch.hs |  4 ++--
 src/Renderer/Split.hs |  2 +-
 test/CorpusSpec.hs    | 30 +++++++++++++-----------------
 6 files changed, 20 insertions(+), 23 deletions(-)

diff --git a/src/Diffing.hs b/src/Diffing.hs
index 6e9fd0e69..a3440dbd6 100644
--- a/src/Diffing.hs
+++ b/src/Diffing.hs
@@ -72,7 +72,7 @@ readAndTranscodeFile path = do
 -- | result.
 -- | Returns the rendered result strictly, so it's always fully evaluated
 -- | with respect to other IO actions.
-diffFiles :: Parser -> Renderer T.Text b -> Both SourceBlob -> IO b
+diffFiles :: Parser -> Renderer T.Text -> Both SourceBlob -> IO T.Text
 diffFiles parser renderer sourceBlobs = do
   let sources = source <$> sourceBlobs
   terms <- sequence $ parser <$> sources
diff --git a/src/Renderer.hs b/src/Renderer.hs
index 35f1f5f43..740e1a236 100644
--- a/src/Renderer.hs
+++ b/src/Renderer.hs
@@ -4,9 +4,10 @@ import Data.Functor.Both
 import Diff
 import Info
 import Source
+import Data.Text
 
 -- | A function that will render a diff, given the two source files.
-type Renderer a b = Diff a Info -> Both SourceBlob -> b
+type Renderer a = Diff a Info -> Both SourceBlob -> Text
 
 data DiffArguments = DiffArguments { format :: Format, output :: Maybe FilePath, outputPath :: FilePath }
 
diff --git a/src/Renderer/JSON.hs b/src/Renderer/JSON.hs
index 42500aec6..1cf8ca78f 100644
--- a/src/Renderer/JSON.hs
+++ b/src/Renderer/JSON.hs
@@ -28,7 +28,7 @@ import Syntax
 import Term
 
 -- | Render a diff to a string representing its JSON.
-json :: Renderer a Text
+json :: Renderer a
 json diff sources = toStrict . toLazyText . encodeToTextBuilder $ object ["rows" .= annotateRows (splitDiffByLines (source <$> sources) diff), "oids" .= (oid <$> sources), "paths" .= (path <$> sources)]
   where annotateRows = fmap (fmap NumberedLine) . numberedRows
 
diff --git a/src/Renderer/Patch.hs b/src/Renderer/Patch.hs
index 44a7ebc7d..972bfe557 100644
--- a/src/Renderer/Patch.hs
+++ b/src/Renderer/Patch.hs
@@ -28,7 +28,7 @@ truncatePatch :: DiffArguments -> Both SourceBlob -> Text
 truncatePatch arguments blobs = pack $ header blobs ++ "#timed_out\nTruncating diff: timeout reached.\n"
 
 -- | Render a diff in the traditional patch format.
-patch :: Renderer a Text
+patch :: Renderer a
 patch diff blobs = pack $ case getLast (foldMap (Last . Just) string) of
   Just c | c /= '\n' -> string ++ "\n\\ No newline at end of file\n"
   _ -> string
@@ -118,7 +118,7 @@ emptyHunk :: Hunk (SplitDiff a Info)
 emptyHunk = Hunk { offset = mempty, changes = [], trailingContext = [] }
 
 -- | Render a diff as a series of hunks.
-hunks :: Renderer a [Hunk (SplitDiff a Info)]
+hunks :: Diff a Info -> Both SourceBlob -> [Hunk (SplitDiff a Info)]
 hunks _ blobs | sources <- source <$> blobs
               , sourcesEqual <- runBothWith (==) sources
               , sourcesNull <- runBothWith (&&) (null <$> sources)
diff --git a/src/Renderer/Split.hs b/src/Renderer/Split.hs
index b98934a3a..d9a9ae7cb 100644
--- a/src/Renderer/Split.hs
+++ b/src/Renderer/Split.hs
@@ -53,7 +53,7 @@ splitPatchToClassName patch = stringValue $ "patch " ++ case patch of
   SplitReplace _ -> "replace"
 
 -- | Render a diff as an HTML split diff.
-split :: Renderer leaf T.Text
+split :: Renderer leaf
 split diff blobs = TL.toStrict . renderHtml
   . docTypeHtml
     . ((head $ link ! A.rel "stylesheet" ! A.href "style.css") <>)
diff --git a/test/CorpusSpec.hs b/test/CorpusSpec.hs
index cd1bb688f..f201ce097 100644
--- a/test/CorpusSpec.hs
+++ b/test/CorpusSpec.hs
@@ -34,23 +34,23 @@ spec = parallel $ do
     examples "test/diffs/" `shouldNotReturn` []
 
   where
-    runTestsIn :: String -> (String -> String -> Expectation) -> SpecWith ()
+    runTestsIn :: String -> (T.Text -> T.Text -> Expectation) -> SpecWith ()
     runTestsIn directory matcher = do
       paths <- runIO $ examples directory
       let tests = correctTests =<< paths
       mapM_ (\ (formatName, renderer, paths, output) -> it (normalizeName (fst paths) ++ " (" ++ formatName ++ ")") $ testDiff renderer paths output matcher) tests
 
-    correctTests :: (Both FilePath, Maybe FilePath, Maybe FilePath, Maybe FilePath) -> [(String, Renderer a String, Both FilePath, Maybe FilePath)]
+    correctTests :: (Both FilePath, Maybe FilePath, Maybe FilePath, Maybe FilePath) -> [(String, Renderer a, Both FilePath, Maybe FilePath)]
     correctTests paths@(_, Nothing, Nothing, Nothing) = testsForPaths paths
     correctTests paths = List.filter (\(_, _, _, output) -> isJust output) $ testsForPaths paths
-    testsForPaths :: (Both FilePath, Maybe FilePath, Maybe FilePath, Maybe FilePath) -> [(String, Renderer a String, Both FilePath, Maybe FilePath)]
+    testsForPaths :: (Both FilePath, Maybe FilePath, Maybe FilePath, Maybe FilePath) -> [(String, Renderer a, Both FilePath, Maybe FilePath)]
     testsForPaths (paths, json, patch, split) = [ ("json", testJSON, paths, json), ("patch", testPatch, paths, patch), ("split", testSplit, paths, split) ]
-    testPatch :: Renderer a String
-    testPatch diff sources = T.unpack $ P.patch diff sources
-    testSplit :: Renderer a String
-    testSplit diff sources = T.unpack $ Split.split diff sources
-    testJSON :: Renderer a String
-    testJSON diff sources = T.unpack $ J.json diff sources
+    testPatch :: Renderer a
+    testPatch diff sources = P.patch diff sources
+    testSplit :: Renderer a
+    testSplit diff sources = Split.split diff sources
+    testJSON :: Renderer a
+    testJSON diff sources = J.json diff sources
 
 
 -- | Return all the examples from the given directory. Examples are expected to
@@ -77,18 +77,14 @@ normalizeName path = addExtension (dropExtension $ dropExtension path) (takeExte
 -- | Given file paths for A, B, and, optionally, a diff, return whether diffing
 -- | the files will produce the diff. If no diff is provided, then the result
 -- | is true, but the diff will still be calculated.
-testDiff :: Renderer T.Text String -> Both FilePath -> Maybe FilePath -> (String -> String -> Expectation) -> Expectation
+testDiff :: Renderer T.Text -> Both FilePath -> Maybe FilePath -> (T.Text -> T.Text -> Expectation) -> Expectation
 testDiff renderer paths diff matcher = do
   sources <- sequence $ readAndTranscodeFile <$> paths
-  actual <- diffFiles parser renderer sourceBlobs
+  actual <- diffFiles parser renderer (sourceBlobs sources)
   case diff of
     Nothing -> matcher actual actual
     Just file -> do
-      expected <- readFile file
+      expected <- T.pack <$> readFile file
       matcher actual expected
   where parser = parserForFilepath (fst paths)
-        sourceBlobs = Both (S.SourceBlob, S.SourceBlob) <*>
-          sources <*>
-          pure mempty <*>
-          paths <*>
-          pure (Just S.defaultPlainBlob)
+        sourceBlobs sources = Both (S.SourceBlob, S.SourceBlob) <*> sources <*> pure mempty <*> paths <*> pure (Just S.defaultPlainBlob)

From 928087e1f5341df9a7fe228afe20c3a95efdc4a6 Mon Sep 17 00:00:00 2001
From: joshvera <vera@github.com>
Date: Mon, 4 Apr 2016 17:38:41 -0400
Subject: [PATCH 13/13] :fire:

---
 test/CorpusSpec.hs | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/test/CorpusSpec.hs b/test/CorpusSpec.hs
index f201ce097..2ddc22a61 100644
--- a/test/CorpusSpec.hs
+++ b/test/CorpusSpec.hs
@@ -44,14 +44,7 @@ spec = parallel $ do
     correctTests paths@(_, Nothing, Nothing, Nothing) = testsForPaths paths
     correctTests paths = List.filter (\(_, _, _, output) -> isJust output) $ testsForPaths paths
     testsForPaths :: (Both FilePath, Maybe FilePath, Maybe FilePath, Maybe FilePath) -> [(String, Renderer a, Both FilePath, Maybe FilePath)]
-    testsForPaths (paths, json, patch, split) = [ ("json", testJSON, paths, json), ("patch", testPatch, paths, patch), ("split", testSplit, paths, split) ]
-    testPatch :: Renderer a
-    testPatch diff sources = P.patch diff sources
-    testSplit :: Renderer a
-    testSplit diff sources = Split.split diff sources
-    testJSON :: Renderer a
-    testJSON diff sources = J.json diff sources
-
+    testsForPaths (paths, json, patch, split) = [ ("json", J.json, paths, json), ("patch", P.patch, paths, patch), ("split", Split.split, paths, split) ]
 
 -- | Return all the examples from the given directory. Examples are expected to
 -- | have the form "foo.A.js", "foo.B.js", "foo.patch.js". Diffs are not