Fix crash on negative integers

Resolves #85

Author: spencerjanssen

src/Data/Text/Format.hs

@@ -73,10 +73,9 @@ shortest = fromString . toShortest . realToFrac
   where
     toShortest :: Double -> String
     toShortest dbl =
-      -- `showFFloat (Just 0) "" 1.0` gives "1.", but we want "1"
-      let intPart = (floor dbl :: Int) in
-        if dbl == (fromIntegral intPart)
-          then showInt intPart ""
+      let intPart = fromIntegral (floor dbl :: Int) in
+        if dbl == intPart
+          then showFFloat (Just 0) intPart ""
           else showFFloat Nothing dbl ""
 #endif
 {-# INLINE shortest #-}

test/Spec.hs

@@ -49,6 +49,7 @@ spec = do
     it "Fixed"    $ format (fixed 4) (12.123456 :: Double) `shouldBe` "12.1235"
     it "Variable" $ format float     (12.123456 :: Double) `shouldBe` "12.123456"
     it "Shortest" $ format shortest  (12.0000 :: Double) `shouldBe` "12"
+    it "Negative" $ format float     (-1.0000 :: Double) `shouldBe` "-1"
 
   describe "Scientific" $ do
     it "sci" $ format sci (scientific 60221409 16) `shouldBe` "6.0221409e23"