Add a newypte wrapper that will call ppShow

Author: yav

Text/Show/Pretty.hs

@@ -36,6 +36,9 @@ module Text.Show.Pretty
     -- * Get location of data files
   , getDataDir
 
+    -- * PPShow newtype wrapper
+  , PPShow(..)
+
   , -- * Preprocessing of values
     PreProc(..), ppHide, ppHideNested, hideCon
 
@@ -63,6 +66,17 @@ import Prelude
 ppValue :: Value -> Doc
 ppValue = valToDoc
 
+{- | This is just a wrapper, so that calling `show` on a value will
+use `ppShow` on it instead.  Convenient for writing tests, so that
+you get a prettier message if the test fails -}
+newtype PPShow a = PPShow a
+  deriving (Eq,Ord)
+
+instance Show a => Show (PPShow a) where
+  show (PPShow a) = ppShow a
+
+
+
 reify :: Show a => a -> Maybe Value
 reify = parseValue . show
 

pretty-show.cabal

@@ -1,5 +1,5 @@
 name:           pretty-show
-version:        1.10
+version:        1.11
 category:       Text
 
 synopsis:       Tools for working with derived `Show` instances and generic
@@ -52,6 +52,8 @@ library
     pretty         >= 1    &&  < 2,
     text,
     filepath,
+    unordered-containers,
+    hashable,
     ghc-prim
   ghc-options: -Wall -O2
   if impl(ghc < 7.4)