lib, web: tweaks to keep building with GHC 7

hledger-lib/Hledger/Data/Journal.hs

@@ -732,7 +732,6 @@ addOrAssignAmountAndCheckAssertionB p@Posting{paccount=acc, pamount=amt, pbalanc
       newbal <- addAmountB acc amt 
       whenM (R.reader bsAssrt) $ checkBalanceAssertionB p newbal
       return p
-  | Nothing <- mba = return p
   | Just BalanceAssertion{baamount,batotal} <- mba = do
       (diff,newbal) <- case batotal of
         True  -> do
@@ -750,6 +749,8 @@ addOrAssignAmountAndCheckAssertionB p@Posting{paccount=acc, pamount=amt, pbalanc
       let p' = p{pamount=diff, poriginal=Just $ originalPosting p}
       whenM (R.reader bsAssrt) $ checkBalanceAssertionB p' newbal
       return p'
+  -- no amount, no balance assertion (GHC 7 doesn't like Nothing <- mba here)
+  | otherwise = return p
 
 -- | Add the posting's amount to its account's running balance, and
 -- optionally check the posting's balance assertion if any.

hledger-web/Hledger/Web/Json.hs

@@ -120,7 +120,7 @@ instance FromJSON Account
 -- https://github.com/PaulJohnson/Haskell-Decimal/issues/6
 --deriving instance Generic Decimal
 --instance FromJSON Decimal
-deriving instance Generic (DecimalRaw Integer)
+deriving instance Generic (DecimalRaw a)
 instance FromJSON (DecimalRaw Integer)
 --
 -- @simonmichael, I think the code in your first comment should work if it compiles—though “work” doesn’t mean you can parse a JSON number directly into a `Decimal` using the generic instance, as you’ve discovered.