imp: cost: Generate totally balanced conversion postings for amounts with costs.

Introduce --infer-equity option which will generate conversion postings.
--cost will override --infer-equity.

This means there will no longer be unbalanced transactions, but will be
offsetting conversion postings to balance things out. For example.

2000-01-01
  a   1 AAA @@ 2 BBB
  b  -2 BBB

When converting to cost, this is treated the same as before.
When used with --infer-equity, this is now treated as:

2000-01-01
  a                               1 AAA
  equity:conversion:AAA-BBB:AAA  -1 AAA
  equity:conversion:AAA-BBB:BBB   2 BBB
  b                              -2 BBB

There is a new account type, Conversion/V, which is a subtype of Equity/E.
The first account declared with this type, if any, is used as the base account
for inferred equity postings in conversion transactions, overriding the default
"equity:conversion".

API changes:

Costing has been changed to ConversionOp with three options:
NoConversionOp, ToCost, and InferEquity.
The first correspond to the previous NoCost and Cost options, while the
third corresponds to the --infer-equity flag.  This converts transactions with costs
(one or more transaction prices) to transactions with equity:conversion postings.
It is in ConversionOp because converting to cost with -B/--cost and inferring conversion
equity postings with --infer-equity are mutually exclusive.

Correspondingly, the cost_ record of ReportOpts has been changed to
conversionop_.

This also removes show_costs_ option in ReportOpts, as its functionality
has been replaced by the richer cost_ option.

hledger-lib/Hledger/Data/Amount.hs

@@ -80,6 +80,7 @@ module Hledger.Data.Amount (
   amountUnstyled,
   showAmountB,
   showAmount,
+  showAmountPrice,
   cshowAmount,
   showAmountWithZeroCommodity,
   showAmountDebug,

hledger-lib/Hledger/Data/Journal.hs

@@ -80,6 +80,7 @@ module Hledger.Data.Journal (
   journalLiabilityAccountQuery,
   journalEquityAccountQuery,
   journalCashAccountQuery,
+  journalConversionAccount,
   -- * Misc
   canonicalStyleFrom,
   nulljournal,
@@ -120,9 +121,10 @@ import Hledger.Utils
 import Hledger.Data.Types
 import Hledger.Data.AccountName
 import Hledger.Data.Amount
+import Hledger.Data.Posting
 import Hledger.Data.Transaction
 import Hledger.Data.TransactionModifier
-import Hledger.Data.Posting
+import Hledger.Data.Valuation
 import Hledger.Query
 
 
@@ -395,7 +397,8 @@ letterPairs _ = []
 -- queries for standard account types
 
 -- | Get a query for accounts of the specified types in this journal. 
--- Account types include Asset, Liability, Equity, Revenue, Expense, Cash.
+-- Account types include:
+-- Asset, Liability, Equity, Revenue, Expense, Cash, Conversion.
 -- For each type, if no accounts were declared with this type, the query 
 -- will instead match accounts with names matched by the case-insensitive 
 -- regular expression provided as a fallback.
@@ -506,6 +509,13 @@ journalProfitAndLossAccountQuery j = Or [journalRevenueAccountQuery j
                                         ,journalExpenseAccountQuery j
                                         ]
 
+-- | The 'AccountName' to use for automatically generated conversion postings.
+journalConversionAccount :: Journal -> AccountName
+journalConversionAccount =
+    headDef (T.pack "equity:conversion")
+    . M.findWithDefault [] Conversion
+    . jdeclaredaccounttypes
+
 -- Various kinds of filtering on journals. We do it differently depending
 -- on the command.
 
@@ -870,8 +880,9 @@ postingInferredmarketPrice p@Posting{pamount} =
 
 -- | Convert all this journal's amounts to cost using the transaction prices, if any.
 -- The journal's commodity styles are applied to the resulting amounts.
-journalToCost :: Journal -> Journal
+journalToCost :: ConversionOp -> Journal -> Journal
-journalToCost j@Journal{jtxns=ts} = j{jtxns=map (transactionToCost styles) ts}
+journalToCost cost j@Journal{jtxns=ts} =
+    j{jtxns=map (transactionToCost (journalConversionAccount j) styles cost) ts}
   where
     styles = journalCommodityStyles j
 

hledger-lib/Hledger/Data/Posting.hs

@@ -81,7 +81,7 @@ import Data.Foldable (asum)
 import qualified Data.Map as M
 import Data.Maybe (fromMaybe, isJust)
 import Data.MemoUgly (memo)
-import Data.List (foldl')
+import Data.List (foldl', sort)
 import qualified Data.Set as S
 import Data.Text (Text)
 import qualified Data.Text as T
@@ -480,9 +480,43 @@ postingApplyValuation :: PriceOracle -> M.Map CommoditySymbol AmountStyle -> Day
 postingApplyValuation priceoracle styles periodlast today v p =
     postingTransformAmount (mixedAmountApplyValuation priceoracle styles periodlast today (postingDate p) v) p
 
--- | Convert this posting's amount to cost, and apply the appropriate amount styles.
+-- | Maybe convert this 'Posting's amount to cost, and apply apply appropriate
-postingToCost :: M.Map CommoditySymbol AmountStyle -> Posting -> Posting
+-- amount styles; or, in --infer-equity mode, remove its cost price and add an
-postingToCost styles = postingTransformAmount (styleMixedAmount styles . mixedAmountCost)
+-- appropriate pair of equity postings.
+postingToCost :: Text -> M.Map CommoditySymbol AmountStyle -> ConversionOp -> Posting -> [Posting]
+postingToCost _          _      NoConversionOp p = [p]
+postingToCost _          styles ToCost         p = [postingTransformAmount (styleMixedAmount styles . mixedAmountCost) p]
+postingToCost equityAcct styles InferEquity    p = taggedPosting : concatMap conversionPostings priceAmounts
+  where
+    taggedPosting
+      | null priceAmounts = p
+      | otherwise         = p{ pcomment = pcomment p `commentAddTag` priceTag
+                             , ptags = priceTag : ptags p
+                             }
+    conversionPostings amt = case aprice amt of
+        Nothing -> []
+        Just _  -> [ cp{ paccount = accountPrefix <> amtCommodity
+                       , pamount = mixedAmount . negate $ amountStripPrices amt
+                       }
+                   , cp{ paccount = accountPrefix <> costCommodity
+                       , pamount = styleMixedAmount styles $ mixedAmount cost
+                       }
+                   ]
+      where
+        cost = amountCost amt
+        amtCommodity  = commodity amt
+        costCommodity = commodity cost
+        cp = p{ pcomment = pcomment p `commentAddTag` ("generated-posting","")
+              , ptags = [("generated-posting", ""), ("_generated-posting", "")]
+              , pbalanceassertion = Nothing
+              , poriginal = Nothing
+              }
+        accountPrefix = mconcat [ equityAcct, ":", T.intercalate "-" $ sort [amtCommodity, costCommodity], ":"]
+        -- Take the commodity of an amount and collapse consecutive spaces to a single space
+        commodity = T.unwords . filter (not . T.null) . T.words . acommodity
+
+    priceTag = ("cost", T.strip . wbToText $ foldMap showAmountPrice priceAmounts)
+    priceAmounts = filter (isJust . aprice) . amountsRaw $ pamount p
 
 -- | Apply a transform function to this posting's amount.
 postingTransformAmount :: (MixedAmount -> MixedAmount) -> Posting -> Posting

hledger-lib/Hledger/Data/Transaction.hs

@@ -202,9 +202,11 @@ transactionApplyValuation :: PriceOracle -> M.Map CommoditySymbol AmountStyle ->
 transactionApplyValuation priceoracle styles periodlast today v =
   transactionTransformPostings (postingApplyValuation priceoracle styles periodlast today v)
 
--- | Convert this transaction's amounts to cost, and apply the appropriate amount styles.
+-- | Maybe convert this 'Transaction's amounts to cost and apply the
-transactionToCost :: M.Map CommoditySymbol AmountStyle -> Transaction -> Transaction
+-- appropriate amount styles; or in --infer-equity mode, replace any
-transactionToCost styles = transactionTransformPostings (postingToCost styles)
+-- transaction prices by a pair of equity postings.
+transactionToCost :: Text -> M.Map CommoditySymbol AmountStyle -> ConversionOp -> Transaction -> Transaction
+transactionToCost equityAcct styles cost t = t{tpostings=concatMap (postingToCost equityAcct styles cost) $ tpostings t}
 
 -- | Apply some account aliases to all posting account names in the transaction, as described by accountNameApplyAliases.
 -- This can fail due to a bad replacement pattern in a regular expression alias.

hledger-lib/Hledger/Data/Types.hs

@@ -151,6 +151,7 @@ data AccountType =
   | Revenue
   | Expense
   | Cash  -- ^ a subtype of Asset - liquid assets to show in cashflow report
+  | Conversion -- ^ a subtype of Equity - account in which to generate conversion postings for transaction prices
   deriving (Show,Eq,Ord,Generic)
 
 -- not worth the trouble, letters defined in accountdirectivep for now

hledger-lib/Hledger/Data/Valuation.hs

@@ -13,7 +13,7 @@ looking up historical market prices (exchange rates) between commodities.
 {-# LANGUAGE DeriveGeneric #-}
 
 module Hledger.Data.Valuation (
-   Costing(..)
+   ConversionOp(..)
   ,ValuationType(..)
   ,PriceOracle
   ,journalPriceOracle
@@ -51,8 +51,8 @@ import Text.Printf (printf)
 ------------------------------------------------------------------------------
 -- Types
 
--- | Whether to convert amounts to cost.
+-- | Which operation to perform on conversion transactions.
-data Costing = Cost | NoCost
+data ConversionOp = NoConversionOp | InferEquity | ToCost
   deriving (Show,Eq)
 
 -- | What kind of value conversion should be done on amounts ?
@@ -98,8 +98,8 @@ priceDirectiveToMarketPrice PriceDirective{..} =
 -- Converting things to value
 
 -- | Convert all component amounts to cost/selling price if requested, and style them.
-mixedAmountToCost :: Costing -> M.Map CommoditySymbol AmountStyle -> MixedAmount -> MixedAmount
+mixedAmountToCost :: M.Map CommoditySymbol AmountStyle -> ConversionOp -> MixedAmount -> MixedAmount
-mixedAmountToCost cost styles = mapMixedAmount (amountToCost cost styles)
+mixedAmountToCost styles cost = mapMixedAmount (amountToCost styles cost)
 
 -- | Apply a specified valuation to this mixed amount, using the
 -- provided price oracle, commodity styles, and reference dates.
@@ -109,9 +109,10 @@ mixedAmountApplyValuation priceoracle styles periodlast today postingdate v =
   mapMixedAmount (amountApplyValuation priceoracle styles periodlast today postingdate v)
 
 -- | Convert an Amount to its cost if requested, and style it appropriately.
-amountToCost :: Costing -> M.Map CommoditySymbol AmountStyle -> Amount -> Amount
+amountToCost :: M.Map CommoditySymbol AmountStyle -> ConversionOp -> Amount -> Amount
-amountToCost NoCost _      = id
+amountToCost styles ToCost         = styleAmount styles . amountCost
-amountToCost Cost   styles = styleAmount styles . amountCost
+amountToCost _      InferEquity    = amountStripPrices
+amountToCost _      NoConversionOp = id
 
 -- | Apply a specified valuation to this amount, using the provided
 -- price oracle, and reference dates. Also fix up its display style

hledger-lib/Hledger/Read/JournalReader.hs

@@ -351,7 +351,7 @@ accountdirectivep = do
   -- XXX added in 1.11, deprecated in 1.13, remove in 1.14
   mtypecode :: Maybe Char <- lift $ optional $ try $ do
     skipNonNewlineSpaces1 -- at least one more space in addition to the one consumed by modifiedaccountp
-    choice $ map char "ALERX"
+    choice $ map char "ALERXV"
 
   -- maybe a comment, on this and/or following lines
   (cmt, tags) <- lift transactioncommentp
@@ -390,10 +390,12 @@ parseAccountTypeCode s =
     "x"          -> Right Expense
     "cash"       -> Right Cash
     "c"          -> Right Cash
+    "conversion" -> Right Conversion
+    "v"          -> Right Conversion
     _            -> Left err
   where
     err = T.unpack $ "invalid account type code "<>s<>", should be one of " <>
-            T.intercalate ", " ["A","L","E","R","X","C","Asset","Liability","Equity","Revenue","Expense","Cash"]
+            T.intercalate ", " ["A","L","E","R","X","C","V","Asset","Liability","Equity","Revenue","Expense","Cash","Conversion"]
 
 -- Add an account declaration to the journal, auto-numbering it.
 addAccountDeclaration :: (AccountName,Text,[Tag]) -> JournalParser m ()

hledger-lib/Hledger/Reports/BalanceReport.hs

@@ -313,7 +313,7 @@ tests_BalanceReport = testGroup "BalanceReport" [
                 ,"  a:b          10h @ $50"
                 ,"  c:d                   "
                 ]) >>= either error' return
-         let j' = journalCanonicaliseAmounts $ journalToCost j -- enable cost basis adjustment
+         let j' = journalCanonicaliseAmounts $ journalToCost ToCost j -- enable cost basis adjustment
          balanceReportAsText defreportopts (balanceReport defreportopts Any j') `is`
            ["                $500  a:b"
            ,"               $-500  c:d"

hledger-lib/Hledger/Reports/BudgetReport.hs

@@ -218,9 +218,9 @@ budgetReportAsText ropts@ReportOpts{..} budgetr = TB.toLazyText $
       balanceReportTableAsText ropts (budgetReportAsTable ropts budgetr)
   where
     title = "Budget performance in " <> showDateSpan (periodicReportSpan budgetr)
-           <> (case cost_ of
+           <> (case conversionop_ of
-                 Cost   -> ", converted to cost"
+                 Just ToCost -> ", converted to cost"
-                 NoCost -> "")
+                 _           -> "")
            <> (case value_ of
                  Just (AtThen _mc)   -> ", valued at posting date"
                  Just (AtEnd _mc)    -> ", valued at period ends"
@@ -386,9 +386,9 @@ budgetReportAsTable
         _   -> -- trace (pshow $ (maybecost actual, maybecost budget))  -- debug missing percentage
                Nothing
       where
-        costedAmounts = case cost_ of
+        costedAmounts = case conversionop_ of
-            Cost   -> amounts . mixedAmountCost
+            Just ToCost -> amounts . mixedAmountCost
-            NoCost -> amounts
+            _           -> amounts
 
     -- | Calculate the percentage of actual change to budget goal for a particular commodity
     percentage' :: Change -> BudgetGoal -> CommoditySymbol -> Maybe Percentage

hledger-lib/Hledger/Reports/EntriesReport.hs

@@ -36,7 +36,7 @@ type EntriesReportItem = Transaction
 entriesReport :: ReportSpec -> Journal -> EntriesReport
 entriesReport rspec@ReportSpec{_rsReportOpts=ropts} =
     sortBy (comparing $ transactionDateFn ropts) . jtxns
-    . journalApplyValuationFromOpts rspec{_rsReportOpts=ropts{show_costs_=True}}
+    . journalApplyValuationFromOpts (setDefaultConversionOp NoConversionOp rspec)
     . filterJournalTransactions (_rsQuery rspec)
 
 tests_EntriesReport = testGroup "EntriesReport" [

hledger-lib/Hledger/Reports/MultiBalanceReport.hs

@@ -257,7 +257,7 @@ getPostings rspec@ReportSpec{_rsQuery=query, _rsReportOpts=ropts} j priceoracle
   where
     rspec' = rspec{_rsQuery=depthless, _rsReportOpts = ropts'}
     ropts' = if isJust (valuationAfterSum ropts)
-        then ropts{value_=Nothing, cost_=NoCost}  -- If we're valuing after the sum, don't do it now
+        then ropts{value_=Nothing, conversionop_=Just NoConversionOp}  -- If we're valuing after the sum, don't do it now
         else ropts
 
     -- The user's query with no depth limit, and expanded to the report span
@@ -432,7 +432,7 @@ displayedAccounts ReportSpec{_rsQuery=query,_rsReportOpts=ropts} valuedaccts
         balance = maybeStripPrices . case accountlistmode_ ropts of
             ALTree | d == depth -> aibalance
             _                   -> aebalance
-          where maybeStripPrices = if show_costs_ ropts then id else mixedAmountStripPrices
+          where maybeStripPrices = if conversionop_ ropts == Just NoConversionOp then id else mixedAmountStripPrices
 
     -- Accounts interesting because they are a fork for interesting subaccounts
     interestingParents = dbg5 "interestingParents" $ case accountlistmode_ ropts of

hledger-lib/Hledger/Reports/ReportOptions.hs

@@ -30,6 +30,7 @@ module Hledger.Reports.ReportOptions (
   defreportopts,
   rawOptsToReportOpts,
   defreportspec,
+  setDefaultConversionOp,
   reportOptsToSpec,
   updateReportSpec,
   updateReportSpecWith,
@@ -69,7 +70,7 @@ import Data.Either (fromRight)
 import Data.Either.Extra (eitherToMaybe)
 import Data.Functor.Identity (Identity(..))
 import Data.List.Extra (find, isPrefixOf, nubSort)
-import Data.Maybe (fromMaybe, mapMaybe)
+import Data.Maybe (fromMaybe, isJust)
 import qualified Data.Text as T
 import Data.Time.Calendar (Day, addDays)
 import Data.Default (Default(..))
@@ -124,7 +125,7 @@ data ReportOpts = ReportOpts {
      period_           :: Period
     ,interval_         :: Interval
     ,statuses_         :: [Status]  -- ^ Zero, one, or two statuses to be matched
-    ,cost_             :: Costing  -- ^ Should we convert amounts to cost, when present?
+    ,conversionop_     :: Maybe ConversionOp  -- ^ Which operation should we apply to conversion transactions?
     ,value_            :: Maybe ValuationType  -- ^ What value should amounts be converted to ?
     ,infer_prices_     :: Bool      -- ^ Infer market prices from transactions ?
     ,depth_            :: Maybe Int
@@ -180,7 +181,7 @@ defreportopts = ReportOpts
     { period_           = PeriodAll
     , interval_         = NoInterval
     , statuses_         = []
-    , cost_             = NoCost
+    , conversionop_     = Nothing
     , value_            = Nothing
     , infer_prices_     = False
     , depth_            = Nothing
@@ -223,7 +224,6 @@ rawOptsToReportOpts d rawopts =
 
     let formatstring = T.pack <$> maybestringopt "format" rawopts
         querystring  = map T.pack $ listofstringopt "args" rawopts  -- doesn't handle an arg like "" right
-        (costing, valuation) = valuationTypeFromRawOpts rawopts
         pretty = fromMaybe False $ alwaysneveropt "pretty" rawopts
 
         format = case parseStringFormat <$> formatstring of
@@ -235,8 +235,8 @@ rawOptsToReportOpts d rawopts =
           {period_           = periodFromRawOpts d rawopts
           ,interval_         = intervalFromRawOpts rawopts
           ,statuses_         = statusesFromRawOpts rawopts
-          ,cost_             = costing
+          ,conversionop_     = conversionOpFromRawOpts rawopts
-          ,value_            = valuation
+          ,value_            = valuationTypeFromRawOpts rawopts
           ,infer_prices_     = boolopt "infer-market-prices" rawopts
           ,depth_            = maybeposintopt "depth" rawopts
           ,date2_            = boolopt "date2" rawopts
@@ -290,6 +290,11 @@ defreportspec = ReportSpec
     , _rsQueryOpts  = []
     }
 
+-- | Set the default ConversionOp.
+setDefaultConversionOp :: ConversionOp -> ReportSpec -> ReportSpec
+setDefaultConversionOp def rspec@ReportSpec{_rsReportOpts=ropts} =
+    rspec{_rsReportOpts=ropts{conversionop_=conversionop_ ropts <|> Just def}}
+
 accountlistmodeopt :: RawOpts -> AccountListMode
 accountlistmodeopt =
   fromMaybe ALFlat . choiceopt parse where
@@ -469,39 +474,32 @@ reportOptsToggleStatus s ropts@ReportOpts{statuses_=ss}
   | s `elem` ss = ropts{statuses_=filter (/= s) ss}
   | otherwise   = ropts{statuses_=simplifyStatuses (s:ss)}
 
--- | Parse the type of valuation and costing to be performed, if any,
+-- | Parse the type of valuation to be performed, if any, specified by -V,
--- specified by -B/--cost, -V, -X/--exchange, or --value flags. It is
+-- -X/--exchange, or --value flags. If there's more than one valuation type,
--- allowed to combine -B/--cost with any other valuation type. If
+-- the rightmost flag wins. This will fail with a usage error if an invalid
--- there's more than one valuation type, the rightmost flag wins.
+-- argument is passed to --value, or if --valuechange is called with a
--- This will fail with a usage error if an invalid argument is passed
+-- valuation type other than -V/--value=end.
--- to --value, or if --valuechange is called with a valuation type
+valuationTypeFromRawOpts :: RawOpts -> Maybe ValuationType
--- other than -V/--value=end.
+valuationTypeFromRawOpts rawopts = case (balancecalcopt rawopts, directval) of
-valuationTypeFromRawOpts :: RawOpts -> (Costing, Maybe ValuationType)
+    (CalcValueChange, Nothing       ) -> Just $ AtEnd Nothing  -- If no valuation requested for valuechange, use AtEnd
-valuationTypeFromRawOpts rawopts = case (balancecalcopt rawopts, directcost, directval) of
+    (CalcValueChange, Just (AtEnd _)) -> directval             -- If AtEnd valuation requested, use it
-    (CalcValueChange, _,      Nothing       ) -> (directcost, Just $ AtEnd Nothing)  -- If no valuation requested for valuechange, use AtEnd
+    (CalcValueChange, _             ) -> usageError "--valuechange only produces sensible results with --value=end"
-    (CalcValueChange, _,      Just (AtEnd _)) -> (directcost, directval)             -- If AtEnd valuation requested, use it
+    (CalcGain,        Nothing       ) -> Just $ AtEnd Nothing  -- If no valuation requested for gain, use AtEnd
-    (CalcValueChange, _,      _             ) -> usageError "--valuechange only produces sensible results with --value=end"
+    (_,               _             ) -> directval             -- Otherwise, use requested valuation
-    (CalcGain,        Cost,   _             ) -> usageError "--gain cannot be combined with --cost"
-    (CalcGain,        NoCost, Nothing       ) -> (directcost, Just $ AtEnd Nothing)  -- If no valuation requested for gain, use AtEnd
-    (_,               _,      _             ) -> (directcost, directval)             -- Otherwise, use requested valuation
   where
-    directcost = if Cost `elem` map fst valuationopts then Cost else NoCost
+    directval = lastMay $ collectopts valuationfromrawopt rawopts
-    directval  = lastMay $ mapMaybe snd valuationopts
-
-    valuationopts = collectopts valuationfromrawopt rawopts
     valuationfromrawopt (n,v)  -- option name, value
-      | n == "B"     = Just (Cost,   Nothing)  -- keep supporting --value=cost for now
+      | n == "V"     = Just $ AtEnd Nothing
-      | n == "V"     = Just (NoCost, Just $ AtEnd Nothing)
+      | n == "X"     = Just $ AtEnd (Just $ T.pack v)
-      | n == "X"     = Just (NoCost, Just $ AtEnd (Just $ T.pack v))
+      | n == "value" = valueopt v
-      | n == "value" = Just $ valueopt v
       | otherwise    = Nothing
     valueopt v
-      | t `elem` ["cost","c"]  = (Cost,   AtEnd . Just <$> mc)  -- keep supporting --value=cost,COMM for now
+      | t `elem` ["cost","c"]  = AtEnd . Just <$> mc  -- keep supporting --value=cost,COMM for now
-      | t `elem` ["then" ,"t"] = (NoCost, Just $ AtThen mc)
+      | t `elem` ["then" ,"t"] = Just $ AtThen mc
-      | t `elem` ["end" ,"e"]  = (NoCost, Just $ AtEnd  mc)
+      | t `elem` ["end" ,"e"]  = Just $ AtEnd  mc
-      | t `elem` ["now" ,"n"]  = (NoCost, Just $ AtNow  mc)
+      | t `elem` ["now" ,"n"]  = Just $ AtNow  mc
       | otherwise = case parsedateM t of
-            Just d  -> (NoCost, Just $ AtDate d mc)
+            Just d  -> Just $ AtDate d mc
             Nothing -> usageError $ "could not parse \""++t++"\" as valuation type, should be: then|end|now|t|e|n|YYYY-MM-DD"
       where
         -- parse --value's value: TYPE[,COMM]
@@ -510,6 +508,22 @@ valuationTypeFromRawOpts rawopts = case (balancecalcopt rawopts, directcost, dir
                    "" -> Nothing
                    c  -> Just $ T.pack c
 
+-- | Parse the type of costing to be performed, if any, specified by -B/--cost
+-- or --value flags. If there's more than one costing type, the rightmost flag
+-- wins. This will fail with a usage error if an invalid argument is passed to
+-- --cost or if a costing type is requested with --gain.
+conversionOpFromRawOpts :: RawOpts -> Maybe ConversionOp
+conversionOpFromRawOpts rawopts
+    | isJust costFlag && balancecalcopt rawopts == CalcGain = usageError "--gain cannot be combined with --cost"
+    | boolopt "infer-equity" rawopts = costFlag <|> Just InferEquity
+    | otherwise = costFlag
+  where
+    costFlag = lastMay $ collectopts conversionopfromrawopt rawopts
+    conversionopfromrawopt (n,v)  -- option name, value
+      | n == "B"                                    = Just ToCost
+      | n == "value", takeWhile (/=',') v `elem` ["cost", "c"] = Just ToCost  -- keep supporting --value=cost for now
+      | otherwise                                   = Nothing
+
 -- | Select the Transaction date accessor based on --date2.
 transactionDateFn :: ReportOpts -> (Transaction -> Day)
 transactionDateFn ReportOpts{..} = if date2_ then transactionDate2 else tdate
@@ -578,9 +592,7 @@ journalApplyValuationFromOptsWith rspec@ReportSpec{_rsReportOpts=ropts} j priceo
   where
     valuation p = maybe id (mixedAmountApplyValuation priceoracle styles (periodEnd p) (_rsDay rspec) (postingDate p)) (value_ ropts)
     gain      p = maybe id (mixedAmountApplyGain      priceoracle styles (periodEnd p) (_rsDay rspec) (postingDate p)) (value_ ropts)
-    costing = case cost_ ropts of
+    costing     = journalToCost (fromMaybe NoConversionOp $ conversionop_ ropts)
-        Cost   -> journalToCost
-        NoCost -> id
 
     -- Find the end of the period containing this posting
     periodEnd  = addDays (-1) . fromMaybe err . mPeriodEnd . postingDate
@@ -605,9 +617,10 @@ mixedAmountApplyValuationAfterSumFromOptsWith ropts j priceoracle =
   where
     valuation mc span = mixedAmountValueAtDate priceoracle styles mc (maybe err (addDays (-1)) $ spanEnd span)
     gain mc span = mixedAmountGainAtDate priceoracle styles mc (maybe err (addDays (-1)) $ spanEnd span)
-    costing = case cost_ ropts of
+    costing = case fromMaybe NoConversionOp $ conversionop_ ropts of
-        Cost   -> styleMixedAmount styles . mixedAmountCost
+        NoConversionOp -> id
-        NoCost -> id
+        InferEquity    -> mixedAmountStripPrices
+        ToCost         -> styleMixedAmount styles . mixedAmountCost
     styles = journalCommodityStyles j
     err = error "mixedAmountApplyValuationAfterSumFromOptsWith: expected all spans to have an end date"
 

hledger-ui/Hledger/UI/AccountsScreen.hs

@@ -285,7 +285,7 @@ asHandle ui0@UIState{
         VtyEvent (EvKey (KChar 'a') []) -> suspendAndResume $ clearScreen >> setCursorPosition 0 0 >> add copts j >> uiReloadJournalIfChanged copts d j ui
         VtyEvent (EvKey (KChar 'A') []) -> suspendAndResume $ void (runIadd (journalFilePath j)) >> uiReloadJournalIfChanged copts d j ui
         VtyEvent (EvKey (KChar 'E') []) -> suspendAndResume $ void (runEditor endPosition (journalFilePath j)) >> uiReloadJournalIfChanged copts d j ui
-        VtyEvent (EvKey (KChar 'B') []) -> continue $ regenerateScreens j d $ toggleCost ui
+        VtyEvent (EvKey (KChar 'B') []) -> continue $ regenerateScreens j d $ toggleConversionOp ui
         VtyEvent (EvKey (KChar 'V') []) -> continue $ regenerateScreens j d $ toggleValue ui
         VtyEvent (EvKey (KChar '0') []) -> continue $ regenerateScreens j d $ setDepth (Just 0) ui
         VtyEvent (EvKey (KChar '1') []) -> continue $ regenerateScreens j d $ setDepth (Just 1) ui

hledger-ui/Hledger/UI/RegisterScreen.hs

@@ -335,7 +335,7 @@ rsHandle ui@UIState{
                           rsItemTransaction=Transaction{tsourcepos=(SourcePos f l c,_)}}) -> (Just (unPos l, Just $ unPos c),f)
 
         -- display mode/query toggles
-        VtyEvent (EvKey (KChar 'B') []) -> rsCenterAndContinue $ regenerateScreens j d $ toggleCost ui
+        VtyEvent (EvKey (KChar 'B') []) -> rsCenterAndContinue $ regenerateScreens j d $ toggleConversionOp ui
         VtyEvent (EvKey (KChar 'V') []) -> rsCenterAndContinue $ regenerateScreens j d $ toggleValue ui
         VtyEvent (EvKey (KChar 'H') []) -> rsCenterAndContinue $ regenerateScreens j d $ toggleHistorical ui
         VtyEvent (EvKey (KChar 't') []) -> rsCenterAndContinue $ regenerateScreens j d $ toggleTree ui

hledger-ui/Hledger/UI/TransactionScreen.hs

@@ -65,9 +65,7 @@ showTxn :: ReportOpts -> ReportSpec -> Journal -> Transaction -> T.Text
 showTxn ropts rspec j t =
       showTransactionOneLineAmounts
     $ maybe id (transactionApplyValuation prices styles periodlast (_rsDay rspec)) (value_ ropts)
-  $ case cost_ ropts of
+    $ maybe id (transactionToCost (journalConversionAccount j) styles) (conversionop_ ropts) t
-        Cost   -> transactionToCost styles t
-        NoCost -> t
     -- (if real_ ropts then filterTransactionPostings (Real True) else id) -- filter postings by --real
   where
     prices = journalPriceOracle (infer_prices_ ropts) j
@@ -187,7 +185,7 @@ tsHandle ui@UIState{aScreen=TransactionScreen{tsTransaction=(i,t), tsTransaction
         -- EvKey (KChar 'E') [] -> continue $ regenerateScreens j d $ stToggleEmpty ui
         -- EvKey (KChar 'C') [] -> continue $ regenerateScreens j d $ stToggleCleared ui
         -- EvKey (KChar 'R') [] -> continue $ regenerateScreens j d $ stToggleReal ui
-        VtyEvent (EvKey (KChar 'B') []) -> continue . regenerateScreens j d $ toggleCost ui
+        VtyEvent (EvKey (KChar 'B') []) -> continue . regenerateScreens j d $ toggleConversionOp ui
         VtyEvent (EvKey (KChar 'V') []) -> continue . regenerateScreens j d $ toggleValue ui
 
         VtyEvent e | e `elem` moveUpEvents   -> continue $ tsSelect iprev tprev ui

hledger-ui/Hledger/UI/UIState.hs

@@ -97,11 +97,13 @@ toggleEmpty :: UIState -> UIState
 toggleEmpty = over empty__ not
 
 -- | Toggle between showing the primary amounts or costs.
-toggleCost :: UIState -> UIState
+toggleConversionOp :: UIState -> UIState
-toggleCost = over cost toggleCostMode
+toggleConversionOp = over conversionop toggleCostMode
   where
-    toggleCostMode Cost   = NoCost
+    toggleCostMode Nothing               = Just ToCost
-    toggleCostMode NoCost = Cost
+    toggleCostMode (Just NoConversionOp) = Just ToCost
+    toggleCostMode (Just InferEquity)    = Just ToCost
+    toggleCostMode (Just ToCost)         = Just NoConversionOp
 
 -- | Toggle between showing primary amounts or default valuation.
 toggleValue :: UIState -> UIState

hledger/Hledger/Cli/CliOptions.hs

@@ -181,6 +181,8 @@ reportflags = [
      ,"'now':  convert to current market value, in default valuation commodity or COMM"
      ,"YYYY-MM-DD: convert to market value on the given date, in default valuation commodity or COMM"
      ])
+  ,flagNone ["infer-equity"] (setboolopt "infer-equity")
+    "in conversion transactions, replace costs (transaction prices) with equity postings, to keep the transactions balanced"
   
   -- history of this flag so far, lest we be confused:
   --  originally --infer-value

hledger/Hledger/Cli/Commands/Balance.hs

@@ -652,9 +652,9 @@ multiBalanceReportAsText ropts@ReportOpts{..} r = TB.toLazyText $
         (_,               Cumulative ) -> "Ending balances (cumulative)"
         (_,               Historical)  -> "Ending balances (historical)"
     valuationdesc =
-        (case cost_ of
+        (case conversionop_ of
-            Cost   -> ", converted to cost"
+            Just ToCost -> ", converted to cost"
-            NoCost -> "")
+            _           -> "")
         <> (case value_ of
             Just (AtThen _mc)    -> ", valued at posting date"
             Just (AtEnd _mc) | changingValuation -> ""

hledger/Hledger/Cli/Commands/Close.hs

@@ -48,9 +48,8 @@ closemode = hledgerCommandMode
 
 -- debugger, beware: close is incredibly devious. simple rules combine to make a horrid maze.
 -- tests are in hledger/test/close.test.
-close CliOpts{rawopts_=rawopts, reportspec_=rspec} j = do
+close CliOpts{rawopts_=rawopts, reportspec_=rspec'} j = do
   let
-    today = _rsDay rspec
     -- show opening entry, closing entry, or (default) both ?
     (opening, closing) =
       case (boolopt "open" rawopts, boolopt "close" rawopts) of
@@ -72,6 +71,9 @@ close CliOpts{rawopts_=rawopts, reportspec_=rspec} j = do
         (Nothing, Just o)  -> (o, o)
         (Nothing, Nothing) -> (T.pack defclosingacct, T.pack defopeningacct)
 
+    ropts = (_rsReportOpts rspec'){balanceaccum_=Historical, accountlistmode_=ALFlat}
+    rspec = setDefaultConversionOp (if show_costs then NoConversionOp else InferEquity) rspec'{_rsReportOpts=ropts}
+
     -- dates of the closing and opening transactions
     --
     -- Close.md:
@@ -90,7 +92,7 @@ close CliOpts{rawopts_=rawopts, reportspec_=rspec} j = do
     -- - `-e 2021`"
     --
     q = _rsQuery rspec
-    yesterday = addDays (-1) today
+    yesterday = addDays (-1) $ _rsDay rspec
     yesterdayorjournalend = case journalLastDay False j of
       Just journalend -> max yesterday journalend
       Nothing         -> yesterday
@@ -100,12 +102,11 @@ close CliOpts{rawopts_=rawopts, reportspec_=rspec} j = do
 
     -- should we show the amount(s) on the equity posting(s) ?
     explicit = boolopt "explicit" rawopts
+    show_costs = boolopt "show-costs" rawopts
 
     -- the balances to close
-    ropts = (_rsReportOpts rspec){balanceaccum_=Historical, accountlistmode_=ALFlat}
+    (acctbals',_) = balanceReport rspec j
-    rspec_ = rspec{_rsReportOpts=ropts}
+    acctbals = map (\(a,_,_,b) -> (a, if show_costs then b else mixedAmountStripPrices b)) acctbals'
-    (acctbals',_) = balanceReport rspec_ j
-    acctbals = map (\(a,_,_,b) -> (a, if show_costs_ ropts then b else mixedAmountStripPrices b)) acctbals'
     totalamt = maSum $ map snd acctbals
 
     -- since balance assertion amounts are required to be exact, the

hledger/Hledger/Cli/Commands/Print.hs

@@ -21,7 +21,7 @@ import qualified Data.Text as T
 import qualified Data.Text.IO as T
 import qualified Data.Text.Lazy as TL
 import qualified Data.Text.Lazy.Builder as TB
-import Lens.Micro (_Just, has)
+import Lens.Micro ((^.), _Just, has)
 import System.Console.CmdArgs.Explicit
 
 import Hledger
@@ -37,6 +37,8 @@ printmode = hledgerCommandMode
     ("show the transaction whose description is most similar to "++arg++", and is most recent")
   ,flagNone ["explicit","x"] (setboolopt "explicit")
     "show all amounts explicitly"
+  ,flagNone ["show-costs"] (setboolopt "show-costs")
+    "show transaction prices even with conversion postings"
   ,flagNone ["new"] (setboolopt "new")
     "show only newer-dated transactions added in each file since last run"
   ,outputFormatFlag ["txt","csv","json","sql"]
@@ -72,7 +74,8 @@ printEntries opts@CliOpts{reportspec_=rspec} j =
            | otherwise   = error' $ unsupportedOutputFormatError fmt  -- PARTIAL:
 
 entriesReportAsText :: CliOpts -> EntriesReport -> TL.Text
-entriesReportAsText opts = TB.toLazyText . foldMap (TB.fromText . showTransaction . whichtxn)
+entriesReportAsText opts =
+    TB.toLazyText . foldMap (TB.fromText . showTransaction . maybeStripPrices . whichtxn)
   where
     whichtxn
       -- With -x, use the fully-inferred txn with all amounts & txn prices explicit.
@@ -84,6 +87,11 @@ entriesReportAsText opts = TB.toLazyText . foldMap (TB.fromText . showTransactio
       | has (value . _Just) opts = id
       -- By default, use the original as-written-in-the-journal txn.
       | otherwise = originalTransaction
+    maybeStripPrices
+      -- Strip prices when inferring equity, unless the show-costs option is set
+      | opts ^. conversionop == Just InferEquity && not (boolopt "show-costs" $ rawopts_ opts) =
+          transactionTransformPostings postingStripPrices
+      | otherwise = id
 
 -- Replace this transaction's postings with the original postings if any, but keep the
 -- current possibly rewritten account names, and the inferred values of any auto postings

hledger/Hledger/Cli/Commands/Roi.hs

@@ -66,7 +66,7 @@ roi CliOpts{rawopts_=rawopts, reportspec_=rspec@ReportSpec{_rsReportOpts=ReportO
     styles = journalCommodityStyles j
     mixedAmountValue periodlast date =
         maybe id (mixedAmountApplyValuation priceOracle styles periodlast today date) value_
-        . mixedAmountToCost cost_ styles
+      . maybe id (mixedAmountToCost styles) conversionop_
 
   let
     ropts = _rsReportOpts rspec

hledger/Hledger/Cli/CompoundBalanceCommand.hs

@@ -152,9 +152,9 @@ compoundBalanceCommand CompoundBalanceCommandSpec{..} opts@CliOpts{reportspec_=r
             _                                              -> Nothing
 
         valuationdesc =
-          (case cost_ of
+          (case conversionop_ of
-               Cost   -> ", converted to cost"
+               Just ToCost -> ", converted to cost"
-               NoCost -> "")
+               _           -> "")
           <> (case value_ of
                Just (AtThen _mc)       -> ", valued at posting date"
                Just (AtEnd _mc) | changingValuation -> ""

hledger/hledger.m4.md

@@ -917,15 +917,22 @@ see the discussion at [#1625](https://github.com/simonmichael/hledger/issues/162
 
 # COSTING
 
-The `-B/--cost` flag converts amounts to their cost or sale amount at transaction time,
+The `-B/--cost` flag converts amounts to their cost or sale amount at
-if they have a [transaction price](#transaction-prices) specified.
+transaction time, if they have a [transaction price](#transaction-prices)
-If this flag is supplied, hledger will perform cost conversion first, and will apply
+specified.
-any market price valuations (if requested) afterwards.
+
+The `--infer-equity` flag generates conversion postings within equity to
+balance any transaction prices.
+The account used is "equity:conversion" by default, but this can be customised
+with an account declaration: `account <conversion_account>  Conversion`.
+
+If either of these flags are supplied, hledger will perform cost conversion
+first, and will apply any market price valuations (if requested) afterwards.
+
 
 # VALUATION
 
-Instead of reporting amounts in their original commodity,
+Instead of reporting amounts in their original commodity, hledger can convert them to
-hledger can convert them to
 cost/sale amount (using the conversion rate recorded in the transaction),
 and/or to market value (using some market price on a certain date).
 This is controlled by the `--value=TYPE[,COMMODITY]` option, which will be described below.
@@ -2914,8 +2921,8 @@ account ACCTNAME  [ACCTTYPE] [;COMMENT]
 
 By adding a `type` tag to the [account directive],
 with value
-`A`, `L`, `E`, `R`, `X`, `C`
+`A`, `L`, `E`, `R`, `X`, `C`, `V`
-(or if you prefer: `Asset`, `Liability`, `Equity`, `Revenue`, `Expense`, `Cash`),
+(or if you prefer: `Asset`, `Liability`, `Equity`, `Revenue`, `Expense`, `Cash`, `Conversion`),
 you can declare hledger accounts to be of a certain type:
 
 - **asset**, 
@@ -2928,6 +2935,9 @@ you can declare hledger accounts to be of a certain type:
 - **cash**\
   a subtype of asset, used for [liquid assets][CCE].
 
+- **conversion**\
+  a subtype of equity, used for [conversion postings](#costing)
+
 Declaring account types is a good idea, since it helps enable the easy 
 [balancesheet], [balancesheetequity], [incomestatement] and [cashflow] reports, 
 and probably other things in future. 

hledger/test/journal/transaction-prices.test

@@ -25,7 +25,50 @@ hledger -f- print --explicit --cost
 
 >>>=0
 
-# 3. print a transaction with a total price
+# 3. --infer-equity generates conversion postings
+hledger -f- print --infer-equity
+<<<
+2011/01/01
+    expenses:foreign currency       €100 @ $1.35
+    assets
+>>>
+2011-01-01
+    expenses:foreign currency            €100  ; cost: @ $1.35
+    equity:conversion:$-€:€             €-100  ; generated-posting:
+    equity:conversion:$-€:$           $135.00  ; generated-posting:
+    assets
+
+>>>=0
+
+# 4. With --infer-equity and --show-costs, the cost is still shown
+hledger -f- print --infer-equity --show-costs
+<<<
+2011/01/01
+    expenses:foreign currency       €100 @ $1.35
+    assets
+>>>
+2011-01-01
+    expenses:foreign currency    €100 @ $1.35  ; cost: @ $1.35
+    equity:conversion:$-€:€             €-100  ; generated-posting:
+    equity:conversion:$-€:$           $135.00  ; generated-posting:
+    assets
+
+>>>=0
+
+# 5. With --cost, --infer-equity is ignored
+hledger -f- print --explicit --cost --infer-equity
+<<<
+2011/01/01
+    expenses:foreign currency       €100 @ $1.35
+    assets
+>>>
+2011-01-01
+    expenses:foreign currency         $135.00
+    assets                           $-135.00
+
+>>>=0
+
+# 6. print a transaction with a total price
 hledger -f - print --explicit
 <<<
 2011/01/01
@@ -38,7 +81,7 @@ hledger -f - print --explicit
 
 >>>=0
 
-# 4. when the balance has exactly two commodities, both unpriced, infer an
+# 7. when the balance has exactly two commodities, both unpriced, infer an
 # implicit conversion price for the first one in terms of the second.
 hledger -f - print --explicit
 <<<
@@ -60,7 +103,7 @@ hledger -f - print --explicit
 
 >>>=0
 
-## 5. another, from ledger tests. Just one posting to price so uses @@.
+# 8. another, from ledger tests. Just one posting to price so uses @@.
 hledger -f - print --explicit
 <<<
 2002/09/30 * 1a1a6305d06ce4b284dba0d267c23f69d70c20be
@@ -73,7 +116,7 @@ hledger -f - print --explicit
 
 >>>=0
 
-# 6. when the balance has more than two commodities, don't bother
+# 9. when the balance has more than two commodities, don't bother
 hledger -f - print
 <<<
 2011/01/01
@@ -82,7 +125,7 @@ hledger -f - print
     expenses:other                    £200
 >>>= !0
 
-# 7. another
+# 10. another
 hledger -f - balance -B
 <<<
 2011/01/01
@@ -97,7 +140,7 @@ hledger -f - balance -B
                    0  
 >>>=0
 
-# 8. transaction in two commodities should balance out properly
+# 11. transaction in two commodities should balance out properly
 hledger -f - balance --cost
 <<<
 2011/01/01 x
@@ -110,10 +153,52 @@ hledger -f - balance --cost
                    0  
 >>>=0
 
-# 9. When commodity price is specified implicitly, transaction should
+# 12. --value=cost,XXX is deprecated, but should still work (for now)
+hledger -f - balance --value=cost,XXX
+<<<
+2011/01/01 x
+  a  10£ @@ 16$
+  b
+>>>
+                 16$  a
+                -16$  b
+--------------------
+                   0  
+>>>=0
+
+# 13. conversion postings should be generated when called --infer-equity
+hledger -f - balance --infer-equity
+<<<
+2011/01/01 x
+  a  10£ @@ 16$
+  b
+>>>
+                 10£  a
+                -16$  b
+                 16$  equity:conversion:$-£:$
+                -10£  equity:conversion:$-£:£
+--------------------
+                   0  
+>>>=0
+
+# 14. transaction should be left unbalanced when called without --cost or --infer-equity
+hledger -f - balance
+<<<
+2011/01/01 x
+  a  10£ @@ 16$
+  b
+>>>
+                 10£  a
+                -16$  b
+--------------------
+                -16$
+                 10£  
+>>>=0
+
+# 15. When commodity price is specified implicitly, transaction should
 #     be considered balanced out even when first amount is negative
 #     (that is, price for it should be determined properly, with proper sign)
-hledger -f - balance
+hledger -f - balance -N
 <<<
 2011/01/01 x
   a  -10£
@@ -121,12 +206,9 @@ hledger -f - balance
 >>>
                 -10£  a
                  16$  b
---------------------
-                 16$
-                -10£  
 >>>=0
 
-# 10. Should not infer prices when --strict is specified
+# 16. Should not infer prices when --strict is specified
 hledger -f - balance --strict
 <<<
 2011/01/01 x
@@ -135,7 +217,7 @@ hledger -f - balance --strict
 >>>
 >>>=1
 
-# 11. When commodity price is specified implicitly, transaction should
+# 17. When commodity price is specified implicitly, transaction should
 #     NOT be considered balanced out when BOTH amounts are negative
 hledger -f - balance
 <<<
@@ -145,7 +227,7 @@ hledger -f - balance
 >>>
 >>>=1
 
-# 12. Differently-priced lots of a commodity should be merged in balance report
+# 18. Differently-priced lots of a commodity should be merged in balance report
 hledger -f - balance
 <<<
 2011/1/1
@@ -159,7 +241,7 @@ hledger -f - balance
                   £2  
 >>>=0
 
-# 13. this should balance
+# 19. this should balance
 hledger -f - balance
 <<<
 2011/1/1
@@ -168,7 +250,7 @@ hledger -f - balance
     c  $-30
 >>>= 0
 
-# 14. these balance because of the unit prices, and should parse successfully
+# 20. these balance because of the unit prices, and should parse successfully
 hledger -f - balance --no-total
 <<<
 1/1
@@ -178,7 +260,7 @@ hledger -f - balance --no-total
                  -1X  a
 >>>= 0
 
-# 15.
+# 21.
 hledger -f - balance --no-total -B
 <<<
 1/1
@@ -187,7 +269,7 @@ hledger -f - balance --no-total -B
 >>>
 >>>= 0
 
-# 16. likewise with total prices. Note how the primary amount's sign is used.
+# 22. likewise with total prices. Note how the primary amount's sign is used.
 hledger -f - balance --no-total
 <<<
 1/1
@@ -197,7 +279,7 @@ hledger -f - balance --no-total
                  -1X  a
 >>>= 0
 
-# 17.
+# 23.
 hledger -f - balance --no-total -B
 <<<
 1/1
@@ -206,7 +288,7 @@ hledger -f - balance --no-total -B
 >>>
 >>>= 0
 
-# 18. here, a's primary amount is 0, and its cost is 1Y; b is the assigned auto-balancing amount of -1Y (per issue 69)
+# 24. here, a's primary amount is 0, and its cost is 1Y; b is the assigned auto-balancing amount of -1Y (per issue 69)
 hledger -f - balance --no-total -E
 <<<
 1/1
@@ -219,7 +301,7 @@ hledger -f - balance --no-total -E
                  -1Y  b
 >>>= 0
 
-# 19. Without -E, a should be hidden because its balance is zero, even though it has a non-zero cost.
+# 25. Without -E, a should be hidden because its balance is zero, even though it has a non-zero cost.
 hledger -f - balance --no-total
 <<<
 1/1
@@ -231,7 +313,7 @@ hledger -f - balance --no-total
                  -1Y  b
 >>>= 0
 
-# 20. the above with -B
+# 26. the above with -B
 hledger -f - balance --no-total -E -B
 <<<
 1/1
@@ -244,6 +326,23 @@ hledger -f - balance --no-total -E -B
                  -1Y  b
 >>>= 0
 
+# 27. The equity account used by --infer-equity can be customised
+hledger -f- print --infer-equity
+<<<
+account  equity:trades   V
+
+2011/01/01
+    expenses:foreign currency       €100 @ $1.35
+    assets
+>>>
+2011-01-01
+    expenses:foreign currency            €100  ; cost: @ $1.35
+    equity:trades:$-€:€                 €-100  ; generated-posting:
+    equity:trades:$-€:$               $135.00  ; generated-posting:
+    assets
+
+>>>=0
+
 # # when the *cost-basis* balance has exactly two commodities, both
 # # unpriced, infer an implicit conversion price for the first one in terms
 # # of the second.