From 9a650fbb51600c932ccf0c01e512a336369aa98b Mon Sep 17 00:00:00 2001
From: Rob Rix <rob.rix@me.com>
Date: Tue, 6 Jun 2017 09:45:23 -0400
Subject: [PATCH] showError returns a String.

---
 src/Data/Syntax/Assignment.hs | 4 +++-
 src/Parser.hs                 | 2 +-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/Data/Syntax/Assignment.hs b/src/Data/Syntax/Assignment.hs
index b68944390..0ae61e9c8 100644
--- a/src/Data/Syntax/Assignment.hs
+++ b/src/Data/Syntax/Assignment.hs
@@ -88,6 +88,7 @@ import qualified Data.IntMap.Lazy as IntMap
 import Data.Ix (inRange)
 import Data.List.NonEmpty (nonEmpty)
 import Data.Record
+import Data.String
 import GHC.Stack
 import qualified Info
 import Prologue hiding (Alt, get, Location, state)
@@ -168,12 +169,13 @@ data ErrorCause symbol
   deriving (Eq, Show)
 
 -- | Pretty-print an Error with reference to the source where it occurred.
-showError :: Show symbol => Source.Source -> Error symbol -> ShowS
+showError :: Show symbol => Source.Source -> Error symbol -> String
 showError source error@Error{..}
   = withSGRCode [SetConsoleIntensity BoldIntensity] (showSourcePos Nothing errorPos) . showString ": " . withSGRCode [SetColor Foreground Vivid Red] (showString "error") . showString ": " . showExpectation error . showChar '\n'
   . showString context -- actualLines results include line endings, so no newline here
   . showString (replicate (succ (Info.column errorPos + lineNumberDigits)) ' ') . withSGRCode [SetColor Foreground Vivid Green] (showChar '^') . showChar '\n'
   . showString (prettyCallStack callStack) . showChar '\n'
+  $ ""
   where context = maybe "\n" (toS . Source.sourceText . sconcat) (nonEmpty [ Source.Source (toS (showLineNumber i)) <> Source.Source ": " <> l | (i, l) <- zip [1..] (Source.actualLines source), inRange (Info.line errorPos - 2, Info.line errorPos) i ])
         showLineNumber n = let s = show n in replicate (lineNumberDigits - length s) ' ' <> s
         lineNumberDigits = succ (floor (logBase 10 (fromIntegral (Info.line errorPos) :: Double)))
diff --git a/src/Parser.hs b/src/Parser.hs
index cd290bd1d..bf152ead1 100644
--- a/src/Parser.hs
+++ b/src/Parser.hs
@@ -66,7 +66,7 @@ runParser parser = case parser of
     let Result err term = assign assignment source ast
     case term of
       Just term -> do
-        traverse_ (putStr . ($ "") . showError source) (toList err <> termErrors term)
+        traverse_ (putStr . showError source) (toList err <> termErrors term)
         pure term
       Nothing -> pure (errorTerm source err)
   TreeSitterParser language tslanguage -> treeSitterParser language tslanguage