;lib: refactor: change AmountPrice to a Maybe

I've wanted to do this for a long time; now that prices are in flux,
seems a good time.

hledger-lib/Hledger/Data/Amount.hs

@@ -165,7 +165,7 @@ instance Num Amount where
 
 -- | The empty simple amount.
 amount, nullamt :: Amount
-amount = Amount{acommodity="", aquantity=0, aprice=NoPrice, astyle=amountstyle, aismultiplier=False}
+amount = Amount{acommodity="", aquantity=0, aprice=Nothing, astyle=amountstyle, aismultiplier=False}
 nullamt = amount
 
 -- | A temporary value for parsed transactions which had no amount specified.
@@ -179,8 +179,8 @@ hrs n = amount{acommodity="h", aquantity=n,           astyle=amountstyle{aspreci
 usd n = amount{acommodity="$", aquantity=roundTo 2 n, astyle=amountstyle{asprecision=2}}
 eur n = amount{acommodity="€", aquantity=roundTo 2 n, astyle=amountstyle{asprecision=2}}
 gbp n = amount{acommodity="£", aquantity=roundTo 2 n, astyle=amountstyle{asprecision=2}}
-amt `at` priceamt = amt{aprice=UnitPrice priceamt}
+amt `at` priceamt = amt{aprice=Just $ UnitPrice priceamt}
-amt @@ priceamt = amt{aprice=TotalPrice priceamt}
+amt @@ priceamt = amt{aprice=Just $ TotalPrice priceamt}
 
 -- | Apply a binary arithmetic operator to two amounts, which should
 -- be in the same commodity if non-zero (warning, this is not checked).
@@ -200,7 +200,7 @@ similarAmountsOp op Amount{acommodity=_,  aquantity=q1, astyle=AmountStyle{aspre
 -- | Convert an amount to the specified commodity, ignoring and discarding
 -- any assigned prices and assuming an exchange rate of 1.
 amountWithCommodity :: CommoditySymbol -> Amount -> Amount
-amountWithCommodity c a = a{acommodity=c, aprice=NoPrice}
+amountWithCommodity c a = a{acommodity=c, aprice=Nothing}
 
 -- | Convert an amount to the commodity of its assigned price, if any.  Notes:
 --
@@ -208,11 +208,11 @@ amountWithCommodity c a = a{acommodity=c, aprice=NoPrice}
 --
 -- - price amounts should be positive, though this is not currently enforced
 costOfAmount :: Amount -> Amount
-costOfAmount a@Amount{aquantity=q, aprice=price} =
+costOfAmount a@Amount{aquantity=q, aprice=mp} =
-    case price of
+    case mp of
-      NoPrice -> a
+      Nothing                                  -> a
-      UnitPrice  p@Amount{aquantity=pq} -> p{aquantity=pq * q}
+      Just (UnitPrice  p@Amount{aquantity=pq}) -> p{aquantity=pq * q}
-      TotalPrice p@Amount{aquantity=pq} -> p{aquantity=pq * signum q}
+      Just (TotalPrice p@Amount{aquantity=pq}) -> p{aquantity=pq * signum q}
 
 -- | Convert this amount to cost, and apply the appropriate amount style.
 amountToCost :: M.Map CommoditySymbol AmountStyle -> Amount -> Amount
@@ -225,8 +225,8 @@ amountToCost styles = styleAmount styles . costOfAmount
 -- Does Decimal division, might be some rounding/irrational number issues.
 amountTotalPriceToUnitPrice :: Amount -> Amount
 amountTotalPriceToUnitPrice 
-  a@Amount{aquantity=q, aprice=TotalPrice pa@Amount{aquantity=pq, astyle=ps@AmountStyle{asprecision=pp}}}
+  a@Amount{aquantity=q, aprice=Just (TotalPrice pa@Amount{aquantity=pq, astyle=ps@AmountStyle{asprecision=pp}})}
-  = a{aprice = UnitPrice pa{aquantity=abs (pq/q), astyle=ps{asprecision=pp+1}}}
+  = a{aprice = Just $ UnitPrice pa{aquantity=abs (pq/q), astyle=ps{asprecision=pp+1}}}
 amountTotalPriceToUnitPrice a = a
 
 -- | Divide an amount's quantity by a constant.
@@ -240,7 +240,7 @@ multiplyAmount n a@Amount{aquantity=q} = a{aquantity=q*n}
 -- | Divide an amount's quantity (and its total price, if it has one) by a constant.
 -- The total price will be kept positive regardless of the multiplier's sign.
 divideAmountAndPrice :: Quantity -> Amount -> Amount
-divideAmountAndPrice n a@Amount{aquantity=q,aprice=p} = a{aquantity=q/n, aprice=f p}
+divideAmountAndPrice n a@Amount{aquantity=q,aprice=p} = a{aquantity=q/n, aprice=f <$> p}
   where
     f (TotalPrice a) = TotalPrice $ abs $ n `divideAmount` a
     f p = p
@@ -248,7 +248,7 @@ divideAmountAndPrice n a@Amount{aquantity=q,aprice=p} = a{aquantity=q/n, aprice=
 -- | Multiply an amount's quantity (and its total price, if it has one) by a constant.
 -- The total price will be kept positive regardless of the multiplier's sign.
 multiplyAmountAndPrice :: Quantity -> Amount -> Amount
-multiplyAmountAndPrice n a@Amount{aquantity=q,aprice=p} = a{aquantity=q*n, aprice=f p}
+multiplyAmountAndPrice n a@Amount{aquantity=q,aprice=p} = a{aquantity=q*n, aprice=f <$> p}
   where
     f (TotalPrice a) = TotalPrice $ abs $ n `multiplyAmount` a
     f p = p
@@ -306,7 +306,7 @@ showAmountDebug Amount{..} = printf "Amount {acommodity=%s, aquantity=%s, aprice
 
 -- | Get the string representation of an amount, without any \@ price.
 showAmountWithoutPrice :: Amount -> String
-showAmountWithoutPrice a = showAmount a{aprice=NoPrice}
+showAmountWithoutPrice a = showAmount a{aprice=Nothing}
 
 -- | Set an amount's internal precision, ie rounds the Decimal representing 
 -- the amount's quantity to some number of decimal places.
@@ -335,21 +335,21 @@ withDecimalPoint = flip setAmountDecimalPoint
 
 -- | Colour version.
 cshowAmountWithoutPrice :: Amount -> String
-cshowAmountWithoutPrice a = cshowAmount a{aprice=NoPrice}
+cshowAmountWithoutPrice a = cshowAmount a{aprice=Nothing}
 
 -- | Get the string representation of an amount, without any price or commodity symbol.
 showAmountWithoutPriceOrCommodity :: Amount -> String
-showAmountWithoutPriceOrCommodity a = showAmount a{acommodity="", aprice=NoPrice}
+showAmountWithoutPriceOrCommodity a = showAmount a{acommodity="", aprice=Nothing}
 
-showAmountPrice :: AmountPrice -> String
+showAmountPrice :: Maybe AmountPrice -> String
-showAmountPrice NoPrice         = ""
+showAmountPrice Nothing                = ""
-showAmountPrice (UnitPrice pa)  = " @ "  ++ showAmount pa
+showAmountPrice (Just (UnitPrice pa))  = " @ "  ++ showAmount pa
-showAmountPrice (TotalPrice pa) = " @@ " ++ showAmount pa
+showAmountPrice (Just (TotalPrice pa)) = " @@ " ++ showAmount pa
 
-showAmountPriceDebug :: AmountPrice -> String
+showAmountPriceDebug :: Maybe AmountPrice -> String
-showAmountPriceDebug NoPrice         = ""
+showAmountPriceDebug Nothing                = ""
-showAmountPriceDebug (UnitPrice pa)  = " @ "  ++ showAmountDebug pa
+showAmountPriceDebug (Just (UnitPrice pa))  = " @ "  ++ showAmountDebug pa
-showAmountPriceDebug (TotalPrice pa) = " @@ " ++ showAmountDebug pa
+showAmountPriceDebug (Just (TotalPrice pa)) = " @@ " ++ showAmountDebug pa
 
 -- | Given a map of standard amount display styles, apply the appropriate one to this amount.
 -- If there's no standard style for this amount's commodity, return the amount unchanged.
@@ -375,7 +375,7 @@ cshowAmount a =
 
 showAmountHelper :: Bool -> Amount -> String
 showAmountHelper _ Amount{acommodity="AUTO"} = ""
-showAmountHelper showzerocommodity a@Amount{acommodity=c, aprice=p, astyle=AmountStyle{..}} =
+showAmountHelper showzerocommodity a@Amount{acommodity=c, aprice=mp, astyle=AmountStyle{..}} =
     case ascommodityside of
       L -> printf "%s%s%s%s" (T.unpack c') space quantity' price
       R -> printf "%s%s%s%s" quantity' space (T.unpack c') price
@@ -385,7 +385,7 @@ showAmountHelper showzerocommodity a@Amount{acommodity=c, aprice=p, astyle=Amoun
       (quantity',c') | displayingzero && not showzerocommodity = ("0","")
                      | otherwise = (quantity, quoteCommoditySymbolIfNeeded c)
       space = if not (T.null c') && ascommodityspaced then " " else "" :: String
-      price = showAmountPrice p
+      price = showAmountPrice mp
 
 -- | Like showAmount, but show a zero amount's commodity if it has one.
 showAmountWithZeroCommodity :: Amount -> String
@@ -503,8 +503,8 @@ normaliseHelper squashprices (Mixed as)
     groupfn | squashprices = (==) `on` acommodity
             | otherwise    = \a1 a2 -> acommodity a1 == acommodity a2 && combinableprices a1 a2
 
-    combinableprices Amount{aprice=NoPrice} Amount{aprice=NoPrice} = True
+    combinableprices Amount{aprice=Nothing} Amount{aprice=Nothing} = True
-    combinableprices Amount{aprice=UnitPrice p1} Amount{aprice=UnitPrice p2} = p1 == p2
+    combinableprices Amount{aprice=Just (UnitPrice p1)} Amount{aprice=Just (UnitPrice p2)} = p1 == p2
     combinableprices _ _ = False
 
 -- | Like normaliseMixedAmount, but combine each commodity's amounts
@@ -682,7 +682,7 @@ cshowMixedAmountWithoutPrice m = intercalate "\n" $ map showamt as
         width = maximumDef 0 $ map (length . showAmount) as
 
 mixedAmountStripPrices :: MixedAmount -> MixedAmount
-mixedAmountStripPrices (Mixed as) = Mixed $ map (\a -> a{aprice=NoPrice}) as
+mixedAmountStripPrices (Mixed as) = Mixed $ map (\a -> a{aprice=Nothing}) as
 
 -- | Get the one-line string representation of a mixed amount, but without
 -- any \@ prices.
@@ -690,14 +690,14 @@ showMixedAmountOneLineWithoutPrice :: MixedAmount -> String
 showMixedAmountOneLineWithoutPrice m = intercalate ", " $ map showAmountWithoutPrice as
     where
       (Mixed as) = normaliseMixedAmountSquashPricesForDisplay $ stripPrices m
-      stripPrices (Mixed as) = Mixed $ map stripprice as where stripprice a = a{aprice=NoPrice}
+      stripPrices (Mixed as) = Mixed $ map stripprice as where stripprice a = a{aprice=Nothing}
 
 -- | Colour version.
 cshowMixedAmountOneLineWithoutPrice :: MixedAmount -> String
 cshowMixedAmountOneLineWithoutPrice m = intercalate ", " $ map cshowAmountWithoutPrice as
     where
       (Mixed as) = normaliseMixedAmountSquashPricesForDisplay $ stripPrices m
-      stripPrices (Mixed as) = Mixed $ map stripprice as where stripprice a = a{aprice=NoPrice}
+      stripPrices (Mixed as) = Mixed $ map stripprice as where stripprice a = a{aprice=Nothing}
 
 -- | Canonicalise a mixed amount's display styles using the provided commodity style map.
 canonicaliseMixedAmount :: M.Map CommoditySymbol AmountStyle -> MixedAmount -> MixedAmount
@@ -718,9 +718,9 @@ tests_Amount = tests "Amount" [
 
      tests "costOfAmount" [
        costOfAmount (eur 1) `is` eur 1
-      ,costOfAmount (eur 2){aprice=UnitPrice $ usd 2} `is` usd 4
+      ,costOfAmount (eur 2){aprice=Just $ UnitPrice $ usd 2} `is` usd 4
-      ,costOfAmount (eur 1){aprice=TotalPrice $ usd 2} `is` usd 2
+      ,costOfAmount (eur 1){aprice=Just $ TotalPrice $ usd 2} `is` usd 2
-      ,costOfAmount (eur (-1)){aprice=TotalPrice $ usd 2} `is` usd (-2)
+      ,costOfAmount (eur (-1)){aprice=Just $ TotalPrice $ usd 2} `is` usd (-2)
     ]
   
     ,tests "isZeroAmount" [
@@ -730,7 +730,7 @@ tests_Amount = tests "Amount" [
   
     ,tests "negating amounts" [
        negate (usd 1) `is` (usd 1){aquantity= -1}
-      ,let b = (usd 1){aprice=UnitPrice $ eur 2} in negate b `is` b{aquantity= -1}
+      ,let b = (usd 1){aprice=Just $ UnitPrice $ eur 2} in negate b `is` b{aquantity= -1}
     ]
   
     ,tests "adding amounts without prices" [

hledger-lib/Hledger/Data/Posting.hs

@@ -200,7 +200,7 @@ sumPostings = sumStrict . map pamount
 -- | Remove all prices of a posting
 removePrices :: Posting -> Posting
 removePrices p = p{ pamount = Mixed $ remove <$> amounts (pamount p) }
-  where remove a = a { aprice = NoPrice }
+  where remove a = a { aprice = Nothing }
 
 -- | Get a posting's (primary) date - it's own primary date if specified,
 -- otherwise the parent transaction's primary date, or the null date if

hledger-lib/Hledger/Data/Transaction.hs

@@ -493,12 +493,12 @@ priceInferrerFor t pt = inferprice
     pcommodities   = map acommodity pamounts
     sumamounts     = amounts $ sumStrict pmixedamounts -- sum normalises to one amount per commodity & price
     sumcommodities = map acommodity sumamounts
-    sumprices      = filter (/=NoPrice) $ map aprice sumamounts
+    sumprices      = filter (/=Nothing) $ map aprice sumamounts
     caninferprices = length sumcommodities == 2 && null sumprices
 
     inferprice p@Posting{pamount=Mixed [a]}
       | caninferprices && ptype p == pt && acommodity a == fromcommodity
-        = p{pamount=Mixed [a{aprice=conversionprice}], poriginal=Just $ originalPosting p}
+        = p{pamount=Mixed [a{aprice=Just conversionprice}], poriginal=Just $ originalPosting p}
       where
         fromcommodity = head $ filter (`elem` sumcommodities) pcommodities -- these heads are ugly but should be safe
         conversionprice

hledger-lib/Hledger/Data/Types.hs

@@ -157,7 +157,7 @@ instance ToMarkup Quantity
 -- | An amount's per-unit or total cost/selling price in another
 -- commodity, as recorded in the journal entry eg with @ or @@.
 -- Docs call this "transaction price". The amount is always positive.
-data AmountPrice = NoPrice | UnitPrice Amount | TotalPrice Amount 
+data AmountPrice = UnitPrice Amount | TotalPrice Amount 
   deriving (Eq,Ord,Typeable,Data,Generic,Show)
 
 instance NFData AmountPrice
@@ -208,7 +208,7 @@ data Amount = Amount {
       aismultiplier :: Bool,            -- ^ kludge: a flag marking this amount and posting as a multiplier
                                         --   in a TMPostingRule. In a regular Posting, should always be false.
       astyle      :: AmountStyle,
-      aprice      :: AmountPrice            -- ^ the (fixed, transaction-specific) price for this amount, if any
+      aprice      :: Maybe AmountPrice  -- ^ the (fixed, transaction-specific) price for this amount, if any
     } deriving (Eq,Ord,Typeable,Data,Generic,Show)
 
 instance NFData Amount

hledger-lib/Hledger/Read/Common.hs

@@ -606,8 +606,8 @@ amountp :: JournalParser m Amount
 amountp = label "amount" $ do
   amount <- amountwithoutpricep
   lift $ skipMany spacenonewline
-  price <- priceamountp
+  mprice <- priceamountp
-  pure $ amount { aprice = price }
+  pure $ amount { aprice = mprice }
 
 amountwithoutpricep :: JournalParser m Amount
 amountwithoutpricep = do
@@ -629,7 +629,7 @@ amountwithoutpricep = do
     let numRegion = (offBeforeNum, offAfterNum)
     (q,prec,mdec,mgrps) <- lift $ interpretNumber numRegion suggestedStyle ambiguousRawNum mExponent
     let s = amountstyle{ascommodityside=L, ascommodityspaced=commodityspaced, asprecision=prec, asdecimalpoint=mdec, asdigitgroups=mgrps}
-    return $ nullamt{acommodity=c, aquantity=sign (sign2 q), aismultiplier=mult, astyle=s, aprice=NoPrice}
+    return $ nullamt{acommodity=c, aquantity=sign (sign2 q), aismultiplier=mult, astyle=s, aprice=Nothing}
 
   rightornosymbolamountp :: Bool -> (Decimal -> Decimal) -> JournalParser m Amount
   rightornosymbolamountp mult sign = label "amount" $ do
@@ -645,7 +645,7 @@ amountwithoutpricep = do
         suggestedStyle <- getAmountStyle c
         (q,prec,mdec,mgrps) <- lift $ interpretNumber numRegion suggestedStyle ambiguousRawNum mExponent
         let s = amountstyle{ascommodityside=R, ascommodityspaced=commodityspaced, asprecision=prec, asdecimalpoint=mdec, asdigitgroups=mgrps}
-        return $ nullamt{acommodity=c, aquantity=sign q, aismultiplier=mult, astyle=s, aprice=NoPrice}
+        return $ nullamt{acommodity=c, aquantity=sign q, aismultiplier=mult, astyle=s, aprice=Nothing}
       -- no symbol amount
       Nothing -> do
         suggestedStyle <- getDefaultAmountStyle
@@ -656,7 +656,7 @@ amountwithoutpricep = do
         let (c,s) = case (mult, defcs) of
               (False, Just (defc,defs)) -> (defc, defs{asprecision=max (asprecision defs) prec})
               _ -> ("", amountstyle{asprecision=prec, asdecimalpoint=mdec, asdigitgroups=mgrps})
-        return $ nullamt{acommodity=c, aquantity=sign q, aismultiplier=mult, astyle=s, aprice=NoPrice}
+        return $ nullamt{acommodity=c, aquantity=sign q, aismultiplier=mult, astyle=s, aprice=Nothing}
 
   -- For reducing code duplication. Doesn't parse anything. Has the type
   -- of a parser only in order to throw parse errors (for convenience).
@@ -714,15 +714,15 @@ quotedcommoditysymbolp =
 simplecommoditysymbolp :: TextParser m CommoditySymbol
 simplecommoditysymbolp = takeWhile1P Nothing (not . isNonsimpleCommodityChar)
 
-priceamountp :: JournalParser m AmountPrice
+priceamountp :: JournalParser m (Maybe AmountPrice)
-priceamountp = option NoPrice $ do
+priceamountp = option Nothing $ do
   char '@'
   priceConstructor <- char '@' *> pure TotalPrice <|> pure UnitPrice
 
   lift (skipMany spacenonewline)
   priceAmount <- amountwithoutpricep <?> "unpriced amount (specifying a price)"
 
-  pure $ priceConstructor priceAmount
+  pure $ Just $ priceConstructor priceAmount
 
 balanceassertionp :: JournalParser m BalanceAssertion
 balanceassertionp = do
@@ -1313,7 +1313,7 @@ tests_Common = tests "Common" [
          acommodity="$"
         ,aquantity=10 -- need to test internal precision with roundTo ? I think not 
         ,astyle=amountstyle{asprecision=0, asdecimalpoint=Nothing}
-        ,aprice=UnitPrice $
+        ,aprice=Just $ UnitPrice $
           amount{
              acommodity="€"
             ,aquantity=0.5
@@ -1325,7 +1325,7 @@ tests_Common = tests "Common" [
          acommodity="$"
         ,aquantity=10 
         ,astyle=amountstyle{asprecision=0, asdecimalpoint=Nothing}
-        ,aprice=TotalPrice $
+        ,aprice=Just $ TotalPrice $
           amount{
              acommodity="€"
             ,aquantity=5

hledger-lib/Hledger/Reports/MultiBalanceReports.hs

@@ -406,7 +406,7 @@ tests_MultiBalanceReports = tests "MultiBalanceReports" [
       (map showw aitems) `is` (map showw eitems)
       ((\(_, b, _) -> showMixedAmountDebug b) atotal) `is` (showMixedAmountDebug etotal) -- we only check the sum of the totals
     usd0 = usd 0
-    amount0 = Amount {acommodity="$", aquantity=0, aprice=NoPrice, astyle=AmountStyle {ascommodityside = L, ascommodityspaced = False, asprecision = 2, asdecimalpoint = Just '.', asdigitgroups = Nothing}, aismultiplier=False}
+    amount0 = Amount {acommodity="$", aquantity=0, aprice=Nothing, astyle=AmountStyle {ascommodityside = L, ascommodityspaced = False, asprecision = 2, asdecimalpoint = Just '.', asdigitgroups = Nothing}, aismultiplier=False}
   in 
    tests "multiBalanceReport" [
       test "null journal"  $

hledger-ui/Hledger/UI/AccountsScreen.hs

@@ -109,7 +109,7 @@ asInit d reset ui@UIState{
                         }
       where
         Mixed amts = normaliseMixedAmountSquashPricesForDisplay $ stripPrices bal
-        stripPrices (Mixed as) = Mixed $ map stripprice as where stripprice a = a{aprice=NoPrice}
+        stripPrices (Mixed as) = Mixed $ map stripprice as where stripprice a = a{aprice=Nothing}
     displayitems = map displayitem items
     -- blanks added for scrolling control, cf RegisterScreen 
     blankitems = replicate 100

hledger/Hledger/Cli/Commands/Close.hs

@@ -45,7 +45,7 @@ close CliOpts{rawopts_=rawopts, reportopts_=ropts} j = do
       -- balance assertion amounts will be unpriced, cf #824
       closingps = [posting{paccount=a
                           ,pamount=mixed [setprec $ negate b]
-                          ,pbalanceassertion=Just assertion{baamount=setprec b{aquantity=0, aprice=NoPrice}}
+                          ,pbalanceassertion=Just assertion{baamount=setprec b{aquantity=0, aprice=Nothing}}
                           }
                   | (a,_,_,mb) <- acctbals
                   , b <- amounts $ normaliseMixedAmountSquashPricesForDisplay mb
@@ -54,7 +54,7 @@ close CliOpts{rawopts_=rawopts, reportopts_=ropts} j = do
 
       openingps = [posting{paccount=a
                           ,pamount=mixed [setprec b]
-                          ,pbalanceassertion=Just assertion{baamount=setprec b{aprice=NoPrice}}
+                          ,pbalanceassertion=Just assertion{baamount=setprec b{aprice=Nothing}}
                           }
                   | (a,_,_,mb) <- acctbals
                   , b <- amounts $ normaliseMixedAmountSquashPricesForDisplay mb

hledger/Hledger/Cli/Commands/Prices.hs

@@ -56,22 +56,22 @@ divideAmount' n a = a' where
 invertPrice :: Amount -> Amount
 invertPrice a =
     case aprice a of
-        NoPrice -> a
+        Nothing -> a
-        UnitPrice pa -> invertPrice
+        Just (UnitPrice pa) -> invertPrice
             -- normalize to TotalPrice
-            a { aprice = TotalPrice pa' } where
+            a { aprice = Just $ TotalPrice pa' } where
-                pa' = ((1 / aquantity a) `divideAmount` pa) { aprice = NoPrice }
+                pa' = ((1 / aquantity a) `divideAmount` pa) { aprice = Nothing }
-        TotalPrice pa ->
+        Just (TotalPrice pa) ->
-            a { aquantity = aquantity pa * signum (aquantity a), acommodity = acommodity pa, aprice = TotalPrice pa' } where
+            a { aquantity = aquantity pa * signum (aquantity a), acommodity = acommodity pa, aprice = Just $ TotalPrice pa' } where
-                pa' = pa { aquantity = abs $ aquantity a, acommodity = acommodity a, aprice = NoPrice, astyle = astyle a }
+                pa' = pa { aquantity = abs $ aquantity a, acommodity = acommodity a, aprice = Nothing, astyle = astyle a }
 
 amountCost :: Day -> Amount -> Maybe PriceDirective
 amountCost d a =
     case aprice a of
-        NoPrice -> Nothing
+        Nothing -> Nothing
-        UnitPrice pa -> Just
+        Just (UnitPrice pa) -> Just
             PriceDirective { pddate = d, pdcommodity = acommodity a, pdamount = pa }
-        TotalPrice pa -> Just
+        Just (TotalPrice pa) -> Just
             PriceDirective { pddate = d, pdcommodity = acommodity a, pdamount = abs (aquantity a) `divideAmount'` pa }
 
 postingCosts :: Posting -> [PriceDirective]