fromJSON tests are now working. Yeah!

src/Nix/Pretty.hs

@@ -13,6 +13,7 @@
 
 module Nix.Pretty where
 
+import           Control.Applicative ((<|>))
 import           Control.Monad
 import           Control.Monad.Free
 import           Data.Fix
@@ -39,6 +40,7 @@ import           Nix.Utils hiding ((<$>))
 #endif
 import           Nix.Value
 import           Prelude hiding ((<$>))
+import           Text.Read (readMaybe)
 
 -- | This type represents a pretty printed nix expression
 -- together with some information about the expression.
@@ -296,8 +298,15 @@ printNix = iter phi . check
     phi (NVStrF ns) = show $ hackyStringIgnoreContext ns
     phi (NVListF l) = "[ " ++ unwords l ++ " ]"
     phi (NVSetF s _) =
-        "{ " ++ concat [ unpack k ++ " = " ++ v ++ "; "
+        "{ " ++ concat [ check (unpack k) ++ " = " ++ v ++ "; "
                        | (k, v) <- sort $ toList s ] ++ "}"
+      where
+        check v =
+            fromMaybe v
+            ((fmap (surround . show) (readMaybe v :: Maybe Int))
+             <|> (fmap (surround . show) (readMaybe v :: Maybe Float)))
+          where
+            surround s = "\"" ++ s ++ "\""
     phi NVClosureF {} = "<<lambda>>"
     phi (NVPathF fp) = fp
     phi (NVBuiltinF name _) = "<<builtin " ++ name ++ ">>"

tests/eval-compare/builtins.fromJSON-01.nix

@@ -2,7 +2,6 @@ with builtins;
 
 let simpleJSON = "{\"foo\": \"39\", \"bar\": 472}";
     screwyJSON = "{\"4275\": \"Please do not fail.\"}";
-      # crazyJSON should be tested once screwyJSON works!
     crazyJSON = "     {
     \"response\": {
         \"success\": 1,
@@ -61,4 +60,4 @@ let simpleJSON = "{\"foo\": \"39\", \"bar\": 472}";
         }
     }
 }";
-in [(fromJSON simpleJSON) (fromJSON screwyJSON)]
+in [(fromJSON simpleJSON) (fromJSON screwyJSON) (fromJSON crazyJSON)]