ADD negative amount lookup

dhall/Types.dhall

@@ -404,7 +404,7 @@ let EntryNumGetter =
     ConstN: a constant value
     AmountN: the value of the 'Amount' column
     -}
-      < LookupN : Text | ConstN : Double | AmountN >
+      < LookupN : Text | ConstN : Double | AmountN | NegAmountN >
 
 let EntryTextGetter =
     {-

lib/Internal/Utils.hs

@@ -343,11 +343,13 @@ collectErrorsIO :: MonadUnliftIO m => [m a] -> m [a]
 collectErrorsIO = mapErrorsIO id
 
 resolveValue :: TxRecord -> EntryNumGetter -> InsertExcept Double
-resolveValue r s = case s of
-  (LookupN t) -> readDouble =<< lookupErr SplitValField t (trOther r)
+resolveValue TxRecord {trOther, trAmount} s = case s of
+  (LookupN t) -> readDouble =<< lookupErr SplitValField t trOther
   (ConstN c) -> return c
-  -- TODO don't coerce to rational in trAmount
-  AmountN -> return $ fromRational $ trAmount r
+  AmountN -> return a
+  NegAmountN -> return $ negate a
+  where
+    a = fromRational trAmount
 
 resolveAcnt :: TxRecord -> SplitAcnt -> InsertExcept T.Text
 resolveAcnt = resolveSplitField AcntField