add a Show instance for AmountDisplayOpts, WideBuilder

For debug logging.

hledger-lib/Hledger/Data/Amount.hs

@@ -878,7 +878,7 @@ data AmountDisplay = AmountDisplay
   { adBuilder :: !WideBuilder  -- ^ String representation of the Amount
   , adTotal   :: !Int            -- ^ Cumulative length of MixedAmount this Amount is part of,
                                 --   including separators
-  }
+  } deriving (Show)
 
 nullAmountDisplay :: AmountDisplay
 nullAmountDisplay = AmountDisplay mempty 0

hledger-lib/Text/WideString.hs

@@ -26,7 +26,7 @@ import qualified Data.Text.Lazy.Builder as TB
 data WideBuilder = WideBuilder
   { wbBuilder :: !TB.Builder
   , wbWidth   :: !Int
-  }
+  } deriving (Show)
 
 instance Semigroup WideBuilder where
   WideBuilder x i <> WideBuilder y j = WideBuilder (x <> y) (i + j)