diff --git a/hledger-lib/Hledger/Data/Amount.hs b/hledger-lib/Hledger/Data/Amount.hs
index d2b705c34..adcadc11d 100644
--- a/hledger-lib/Hledger/Data/Amount.hs
+++ b/hledger-lib/Hledger/Data/Amount.hs
@@ -466,6 +466,7 @@ instance Num MixedAmount where
     fromInteger i = Mixed [fromInteger i]
     negate (Mixed as) = Mixed $ map negate as
     (+) (Mixed as) (Mixed bs) = normaliseMixedAmount $ Mixed $ as ++ bs
+    -- PARTIAL:
     (*)    = error' "error, mixed amounts do not support multiplication"
     abs    = error' "error, mixed amounts do not support abs"
     signum = error' "error, mixed amounts do not support signum"
diff --git a/hledger-lib/Hledger/Data/Commodity.hs b/hledger-lib/Hledger/Data/Commodity.hs
index f01449bf5..2903694d4 100644
--- a/hledger-lib/Hledger/Data/Commodity.hs
+++ b/hledger-lib/Hledger/Data/Commodity.hs
@@ -59,7 +59,7 @@ commoditysymbols =
 -- | Look up one of the sample commodities' symbol by name.
 comm :: String -> CommoditySymbol
 comm name = snd $ fromMaybe
-              (error' "commodity lookup failed")
+              (error' "commodity lookup failed")  -- PARTIAL:
               (find (\n -> fst n == name) commoditysymbols)
 
 -- | Find the conversion rate between two commodities. Currently returns 1.
diff --git a/hledger-lib/Hledger/Data/Dates.hs b/hledger-lib/Hledger/Data/Dates.hs
index 517a06a30..28bfc58f9 100644
--- a/hledger-lib/Hledger/Data/Dates.hs
+++ b/hledger-lib/Hledger/Data/Dates.hs
@@ -241,7 +241,7 @@ splitspan start next span@(DateSpan (Just s) (Just e))
           | otherwise = DateSpan (Just subs) (Just sube) : splitspan' start next (DateSpan (Just sube) (Just e))
           where subs = start s
                 sube = next subs
-      splitspan' _ _ _ = error' "won't happen, avoids warnings"
+      splitspan' _ _ _ = error' "won't happen, avoids warnings"  -- PARTIAL:
 
 -- | Count the days in a DateSpan, or if it is open-ended return Nothing.
 daysInSpan :: DateSpan -> Maybe Integer
@@ -344,7 +344,7 @@ parsePeriodExpr refdate s = parsewith (periodexprp refdate <* eof) (T.toLower s)
 -- | Like parsePeriodExpr, but call error' on failure.
 parsePeriodExpr' :: Day -> Text -> (Interval, DateSpan)
 parsePeriodExpr' refdate s =
-  either (error' . ("failed to parse:" ++) . customErrorBundlePretty) id $
+  either (error' . ("failed to parse:" ++) . customErrorBundlePretty) id $  -- PARTIAL:
   parsePeriodExpr refdate s
 
 maybePeriod :: Day -> Text -> Maybe (Interval,DateSpan)
@@ -385,6 +385,7 @@ spanFromSmartDate refdate sdate = DateSpan (Just b) (Just e)
       span (SmartRel This Year)    = (thisyear refdate, nextyear refdate)
       span (SmartRel Last Year)    = (prevyear refdate, thisyear refdate)
       span (SmartRel Next Year)    = (nextyear refdate, startofyear $ addGregorianYearsClip 2 refdate)
+      -- PARTIAL:
       span s@(SmartYMD Nothing Nothing Nothing)   = error' $ "Ill-defined SmartDate " ++ show s
       span s@(SmartYMD (Just _) Nothing (Just _)) = error' $ "Ill-defined SmartDate " ++ show s
       span (SmartYMD y m (Just d)) = (day, nextday day) where day = fromGregorian (fromMaybe ry y) (fromMaybe rm m) d
@@ -398,7 +399,7 @@ spanFromSmartDate refdate sdate = DateSpan (Just b) (Just e)
 -- the provided reference date, or raise an error.
 fixSmartDateStr :: Day -> Text -> String
 fixSmartDateStr d s =
-  either (error' . printf "could not parse date %s %s" (show s) . show) id $
+  either (error' . printf "could not parse date %s %s" (show s) . show) id $  -- PARTIAL:
   (fixSmartDateStrEither d s :: Either (ParseErrorBundle Text CustomErr) String)
 
 -- | A safe version of fixSmartDateStr.
@@ -562,6 +563,7 @@ startofyear day = fromGregorian y 1 1 where (y,_,_) = toGregorian day
 -- 2017-01-01
 nthdayofyearcontaining :: Month -> MonthDay -> Day -> Day
 nthdayofyearcontaining m md date
+  -- PARTIAL:
   | not (validMonth m)  = error' $ "nthdayofyearcontaining: invalid month "++show m
   | not (validDay   md) = error' $ "nthdayofyearcontaining: invalid day "  ++show md
   | mmddOfSameYear <= date = mmddOfSameYear
@@ -590,6 +592,7 @@ nthdayofyearcontaining m md date
 -- 2017-10-30
 nthdayofmonthcontaining :: MonthDay -> Day -> Day
 nthdayofmonthcontaining md date
+  -- PARTIAL:
   | not (validDay md) = error' $ "nthdayofmonthcontaining: invalid day "  ++show md
   | nthOfSameMonth <= date = nthOfSameMonth
   | otherwise = nthOfPrevMonth
@@ -645,8 +648,10 @@ nthweekdayofmonthcontaining n wd d | nthWeekdaySameMonth <= d  = nthWeekdaySameM
           nthWeekdayPrevMonth = advancetonthweekday n wd $ prevmonth d
 
 -- | Advance to nth weekday wd after given start day s
+-- Can call error.
 advancetonthweekday :: Int -> WeekDay -> Day -> Day
 advancetonthweekday n wd s =
+  -- PARTIAL:
   maybe err (addWeeks (n-1)) $ firstMatch (>=s) $ iterate (addWeeks 1) $ firstweekday s
   where
     err = error' "advancetonthweekday: should not happen"
@@ -694,7 +699,7 @@ parsedateM s = asum [
 -- >>> parsedate "2008/02/03"
 -- 2008-02-03
 parsedate :: String -> Day
-parsedate s =  fromMaybe (error' $ "could not parse date \"" ++ s ++ "\"")
+parsedate s =  fromMaybe (error' $ "could not parse date \"" ++ s ++ "\"")  -- PARTIAL:
                          (parsedateM s)
 -- doctests I haven't been able to make compatible with both GHC 7 and 8
 -- -- >>> parsedate "2008/02/03/"
diff --git a/hledger-lib/Hledger/Data/Journal.hs b/hledger-lib/Hledger/Data/Journal.hs
index 766af25e4..ac46f682a 100644
--- a/hledger-lib/Hledger/Data/Journal.hs
+++ b/hledger-lib/Hledger/Data/Journal.hs
@@ -311,7 +311,7 @@ journalCashAccountQuery  :: Journal -> Query
 journalCashAccountQuery j =
   case M.lookup Cash (jdeclaredaccounttypes j) of
     Just _  -> journalAccountTypeQuery [Cash] notused j
-      where notused = error' "journalCashAccountQuery: this should not have happened!" -- XXX ugly
+      where notused = error' "journalCashAccountQuery: this should not have happened!"  -- PARTIAL:
     Nothing -> And [journalAssetAccountQuery j
                    ,Not $ Acct "(investment|receivable|:A/R|:fixed)"
                    ]
diff --git a/hledger-lib/Hledger/Data/Json.hs b/hledger-lib/Hledger/Data/Json.hs
index b69b6acfa..551cb3964 100644
--- a/hledger-lib/Hledger/Data/Json.hs
+++ b/hledger-lib/Hledger/Data/Json.hs
@@ -242,6 +242,7 @@ writeJsonFile f = TL.writeFile f . toJsonText
 readJsonFile :: FromJSON a => FilePath -> IO a
 readJsonFile f = do
   bl <- BL.readFile f
+  -- PARTIAL:
   let v = fromMaybe (error $ "could not decode JSON in "++show f++" to target value")
           (decode bl :: Maybe Value)
   case fromJSON v :: FromJSON a => Result a of
diff --git a/hledger-lib/Hledger/Data/PeriodicTransaction.hs b/hledger-lib/Hledger/Data/PeriodicTransaction.hs
index e4420b281..7d18a4110 100644
--- a/hledger-lib/Hledger/Data/PeriodicTransaction.hs
+++ b/hledger-lib/Hledger/Data/PeriodicTransaction.hs
@@ -38,7 +38,7 @@ _ptgen str = do
     t = T.pack str
     (i,s) = parsePeriodExpr' nulldate t
   case checkPeriodicTransactionStartDate i s t of
-    Just e  -> error' e
+    Just e  -> error' e  -- PARTIAL:
     Nothing ->
       mapM_ (putStr . showTransaction) $
         runPeriodicTransaction
@@ -50,7 +50,7 @@ _ptgenspan str span = do
     t = T.pack str
     (i,s) = parsePeriodExpr' nulldate t
   case checkPeriodicTransactionStartDate i s t of
-    Just e  -> error' e
+    Just e  -> error' e  -- PARTIAL:
     Nothing ->
       mapM_ (putStr . showTransaction) $
         runPeriodicTransaction
diff --git a/hledger-lib/Hledger/Data/Timeclock.hs b/hledger-lib/Hledger/Data/Timeclock.hs
index 720199c9b..78ea2dd54 100644
--- a/hledger-lib/Hledger/Data/Timeclock.hs
+++ b/hledger-lib/Hledger/Data/Timeclock.hs
@@ -94,7 +94,7 @@ entryFromTimeclockInOut :: TimeclockEntry -> TimeclockEntry -> Transaction
 entryFromTimeclockInOut i o
     | otime >= itime = t
     | otherwise =
-        error' $ "clock-out time less than clock-in time in:\n" ++ showTransaction t
+        error' $ "clock-out time less than clock-in time in:\n" ++ showTransaction t  -- PARTIAL:
     where
       t = Transaction {
             tindex       = 0,
diff --git a/hledger-lib/Hledger/Data/Valuation.hs b/hledger-lib/Hledger/Data/Valuation.hs
index 956f313be..a6ba473b5 100644
--- a/hledger-lib/Hledger/Data/Valuation.hs
+++ b/hledger-lib/Hledger/Data/Valuation.hs
@@ -167,7 +167,7 @@ amountApplyValuation priceoracle styles periodlast mreportlast today ismultiperi
   case v of
     AtCost    Nothing            -> styleAmount styles $ amountCost a
     AtCost    mc                 -> amountValueAtDate priceoracle styles mc periodlast $ styleAmount styles $ amountCost a
-    AtThen    _mc                -> error' unsupportedValueThenError  -- TODO
+    AtThen    _mc                -> error' unsupportedValueThenError  -- PARTIAL:
                                  -- amountValueAtDate priceoracle styles mc periodlast a  -- posting date unknown, handle like AtEnd
     AtEnd     mc                 -> amountValueAtDate priceoracle styles mc periodlast a
     AtNow     mc                 -> amountValueAtDate priceoracle styles mc today a
@@ -402,7 +402,7 @@ node m = fst . fst . mkNode m
 -- lowest-sorting label is used.
 pathEdgeLabels :: (Show b, Ord b) => Gr a b -> [Node] -> [b]
 pathEdgeLabels g = map frommaybe . map (nodesEdgeLabel g) . pathEdges
-  where frommaybe = fromMaybe (error' "pathEdgeLabels: expected no Nothings here")
+  where frommaybe = fromMaybe (error' "pathEdgeLabels: expected no Nothings here")  -- PARTIAL:
 
 -- | Convert a path to node pairs representing the path's edges.
 pathEdges :: [Node] -> [(Node,Node)]
diff --git a/hledger-lib/Hledger/Query.hs b/hledger-lib/Hledger/Query.hs
index 27ffd58a7..5b08083e1 100644
--- a/hledger-lib/Hledger/Query.hs
+++ b/hledger-lib/Hledger/Query.hs
@@ -282,7 +282,7 @@ parseQueryTerm _ (T.stripPrefix "status:" -> Just s) =
         case parseStatus s of Left e   -> Left $ "\"status:"++T.unpack s++"\" gave a parse error: " ++ e
                               Right st -> Right $ Left $ StatusQ st
 parseQueryTerm _ (T.stripPrefix "real:" -> Just s) = Right $ Left $ Real $ parseBool s || T.null s
-parseQueryTerm _ (T.stripPrefix "amt:" -> Just s) = Right $ Left $ Amt ord q where (ord, q) = either error id $ parseAmountQueryTerm s
+parseQueryTerm _ (T.stripPrefix "amt:" -> Just s) = Right $ Left $ Amt ord q where (ord, q) = either error id $ parseAmountQueryTerm s  -- PARTIAL:
 parseQueryTerm _ (T.stripPrefix "empty:" -> Just s) = Right $ Left $ Empty $ parseBool s
 parseQueryTerm _ (T.stripPrefix "depth:" -> Just s)
   | n >= 0    = Right $ Left $ Depth n
diff --git a/hledger-lib/Hledger/Read.hs b/hledger-lib/Hledger/Read.hs
index ac05b59d0..805551306 100644
--- a/hledger-lib/Hledger/Read.hs
+++ b/hledger-lib/Hledger/Read.hs
@@ -90,7 +90,7 @@ journalDefaultFilename  = ".hledger.journal"
 -- | Read a Journal from the given text, assuming journal format; or
 -- throw an error.
 readJournal' :: Text -> IO Journal
-readJournal' t = readJournal def Nothing t >>= either error' return
+readJournal' t = readJournal def Nothing t >>= either error' return  -- PARTIAL:
 
 -- | @readJournal iopts mfile txt@
 --
@@ -116,7 +116,7 @@ readJournal iopts mpath txt = do
 
 -- | Read the default journal file specified by the environment, or raise an error.
 defaultJournal :: IO Journal
-defaultJournal = defaultJournalPath >>= readJournalFile def >>= either error' return
+defaultJournal = defaultJournalPath >>= readJournalFile def >>= either error' return  -- PARTIAL:
 
 -- | Get the default journal file path specified by the environment.
 -- Like ledger, we look first for the LEDGER_FILE environment
diff --git a/hledger-lib/Hledger/Read/Common.hs b/hledger-lib/Hledger/Read/Common.hs
index 02df5521a..7029f5e46 100644
--- a/hledger-lib/Hledger/Read/Common.hs
+++ b/hledger-lib/Hledger/Read/Common.hs
@@ -713,7 +713,7 @@ amountp' :: String -> Amount
 amountp' s =
   case runParser (evalStateT (amountp <* eof) nulljournal) "" (T.pack s) of
     Right amt -> amt
-    Left err  -> error' $ show err -- XXX should throwError
+    Left err  -> error' $ show err  -- PARTIAL: XXX should throwError
 
 -- | Parse a mixed amount from a string, or get an error.
 mamountp' :: String -> MixedAmount
diff --git a/hledger-lib/Hledger/Read/CsvReader.hs b/hledger-lib/Hledger/Read/CsvReader.hs
index b34034f5d..4b662cdbe 100644
--- a/hledger-lib/Hledger/Read/CsvReader.hs
+++ b/hledger-lib/Hledger/Read/CsvReader.hs
@@ -101,7 +101,7 @@ reader = Reader
   {rFormat     = "csv"
   ,rExtensions = ["csv","tsv","ssv"]
   ,rReadFn     = parse
-  ,rParser    = error' "sorry, CSV files can't be included yet"
+  ,rParser    = error' "sorry, CSV files can't be included yet"  -- PARTIAL:
   }
 
 -- | Parse and post-process a "Journal" from CSV data, or give an error.
@@ -908,6 +908,7 @@ transactionFromCsvRecord sourcepos rules record = t
 
     mdateformat = rule "date-format"
     date        = fromMaybe "" $ fieldval "date"
+    -- PARTIAL:
     date'       = fromMaybe (error' $ mkdateerror "date" date mdateformat) $ parsedate' date
     mdate2      = fieldval "date2"
     mdate2'     = maybe Nothing (maybe (error' $ mkdateerror "date2" (fromMaybe "" mdate2) mdateformat) Just . parsedate') mdate2
@@ -1010,7 +1011,7 @@ getAmount rules record currency p1IsVirtual n =
       [] -> Nothing
       [(f,a)] | "-out" `isSuffixOf` f -> Just (-a)  -- for -out fields, flip the sign
       [(_,a)] -> Just a
-      fs      -> error' $ unlines $ [
+      fs      -> error' $ unlines $ [  -- PARTIAL:
          "multiple non-zero amounts or multiple zero amounts assigned,"
         ,"please ensure just one. (https://hledger.org/csv.html#amount)"
         ,"  " ++ showRecord record
@@ -1028,7 +1029,7 @@ getAmount rules record currency p1IsVirtual n =
     -- The CSV rules and record are provided for the error message.
     parseAmount :: CsvRules -> CsvRecord -> String -> String -> MixedAmount
     parseAmount rules record currency amountstr =
-      either mkerror (Mixed . (:[])) $
+      either mkerror (Mixed . (:[])) $  -- PARTIAL:
       runParser (evalStateT (amountp <* eof) nulljournal) "" $
       T.pack $ (currency++) $ simplifySign amountstr
       where
@@ -1086,7 +1087,7 @@ mkBalanceAssertion rules record (amt, pos) = assrt{baamount=amt, baposition=pos}
         Just "=="  -> nullassertion{batotal=True}
         Just "=*"  -> nullassertion{bainclusive=True}
         Just "==*" -> nullassertion{batotal=True, bainclusive=True}
-        Just x     -> error' $ unlines
+        Just x     -> error' $ unlines  -- PARTIAL:
           [ "balance-type \"" ++ x ++"\" is invalid. Use =, ==, =* or ==*."
           , showRecord record
           , showRules rules record
diff --git a/hledger-lib/Hledger/Reports/AccountTransactionsReport.hs b/hledger-lib/Hledger/Reports/AccountTransactionsReport.hs
index d820ffb4b..461db5919 100644
--- a/hledger-lib/Hledger/Reports/AccountTransactionsReport.hs
+++ b/hledger-lib/Hledger/Reports/AccountTransactionsReport.hs
@@ -110,13 +110,14 @@ accountTransactionsReport ropts j reportq thisacctq = (label, items)
       filter (matchesTransaction thisacctq . filterTransactionPostings (And [realq, statusq])) ts2
 
     -- maybe convert these transactions to cost or value
+    -- PARTIAL:
     prices = journalPriceOracle (infer_value_ ropts) j
     styles = journalCommodityStyles j
     periodlast =
       fromMaybe (error' "journalApplyValuation: expected a non-empty journal") $ -- XXX shouldn't happen
       reportPeriodOrJournalLastDay ropts j
     mreportlast = reportPeriodLastDay ropts
-    today = fromMaybe (error' "journalApplyValuation: could not pick a valuation date, ReportOpts today_ is unset") $ today_ ropts
+    today = fromMaybe (error' "journalApplyValuation: could not pick a valuation date, ReportOpts today_ is unset") $ today_ ropts -- XXX shouldn't happen
     multiperiod = interval_ ropts /= NoInterval
     tval = case value_ ropts of
              Just v  -> \t -> transactionApplyValuation prices styles periodlast mreportlast today multiperiod t v
diff --git a/hledger-lib/Hledger/Reports/BudgetReport.hs b/hledger-lib/Hledger/Reports/BudgetReport.hs
index 9422e0c02..7f3669ffd 100644
--- a/hledger-lib/Hledger/Reports/BudgetReport.hs
+++ b/hledger-lib/Hledger/Reports/BudgetReport.hs
@@ -101,7 +101,7 @@ budgetReport ropts' assrt reportspan d j = dbg1 "sortedbudgetreport" budgetrepor
 -- their purpose is to set goal amounts (of change) per account and period.
 budgetJournal :: Bool -> ReportOpts -> DateSpan -> Journal -> Journal
 budgetJournal assrt _ropts reportspan j =
-  either error' id $ journalBalanceTransactions assrt j{ jtxns = budgetts }
+  either error' id $ journalBalanceTransactions assrt j{ jtxns = budgetts }  -- PARTIAL:
   where
     budgetspan = dbg2 "budgetspan" $ reportspan
     budgetts =
@@ -218,7 +218,7 @@ budgetReportAsText ropts@ReportOpts{..} budgetr =
       (showDateSpan $ periodicReportSpan budgetr)
       (case value_ of
         Just (AtCost _mc)   -> ", valued at cost"
-        Just (AtThen _mc)   -> error' unsupportedValueThenError  -- TODO
+        Just (AtThen _mc)   -> error' unsupportedValueThenError  -- PARTIAL:
         Just (AtEnd _mc)    -> ", valued at period ends"
         Just (AtNow _mc)    -> ", current value"
         -- XXX duplicates the above
diff --git a/hledger-lib/Hledger/Reports/EntriesReport.hs b/hledger-lib/Hledger/Reports/EntriesReport.hs
index 4872dab01..bb5f60f5f 100644
--- a/hledger-lib/Hledger/Reports/EntriesReport.hs
+++ b/hledger-lib/Hledger/Reports/EntriesReport.hs
@@ -45,7 +45,7 @@ entriesReport ropts@ReportOpts{..} q j@Journal{..} =
           where
             periodlast  = fromMaybe today $ reportPeriodOrJournalLastDay ropts j
             mreportlast = reportPeriodLastDay ropts
-            today       = fromMaybe (error' "erValue: could not pick a valuation date, ReportOpts today_ is unset") today_  -- should not happen
+            today       = fromMaybe (error' "erValue: could not pick a valuation date, ReportOpts today_ is unset") today_  -- PARTIAL: should not happen
 
 tests_EntriesReport = tests "EntriesReport" [
   tests "entriesReport" [
diff --git a/hledger-lib/Hledger/Reports/MultiBalanceReport.hs b/hledger-lib/Hledger/Reports/MultiBalanceReport.hs
index d3cbda6fb..edb409480 100644
--- a/hledger-lib/Hledger/Reports/MultiBalanceReport.hs
+++ b/hledger-lib/Hledger/Reports/MultiBalanceReport.hs
@@ -318,7 +318,7 @@ accumValueAmounts :: ReportOpts -> Journal -> PriceOracle -> [DateSpan]
                   -> HashMap ClippedAccountName Account
                   -> HashMap ClippedAccountName (Map DateSpan Account)
                   -> HashMap ClippedAccountName (Map DateSpan Account)
-accumValueAmounts ropts j priceoracle colspans startbals acctchanges =
+accumValueAmounts ropts j priceoracle colspans startbals acctchanges =  -- PARTIAL:
     HM.mapWithKey processRow $ acctchanges <> (mempty <$ startbals)
   where
     -- Must accumulate before valuing, since valuation can change without any
@@ -565,10 +565,13 @@ subaccountTallies as = foldr incrementParent mempty allaccts
     allaccts = expandAccountNames as
     incrementParent a = HM.insertWith (+) (parentAccountName a) 1
 
--- | Helper to calculate the percentage from two mixed. Keeps the sign of the first argument.
+-- | A helper: what percentage is the second mixed amount of the first ?
+-- Keeps the sign of the first amount.
 -- Uses unifyMixedAmount to unify each argument and then divides them.
+-- Both amounts should be in the same, single commodity.
+-- This can call error if the arguments are not right.
 perdivide :: MixedAmount -> MixedAmount -> MixedAmount
-perdivide a b = fromMaybe (error' errmsg) $ do
+perdivide a b = fromMaybe (error' errmsg) $ do  -- PARTIAL:
     a' <- unifyMixedAmount a
     b' <- unifyMixedAmount b
     guard $ amountIsZero a' || amountIsZero b' || acommodity a' == acommodity b'
diff --git a/hledger-lib/Hledger/Reports/PostingsReport.hs b/hledger-lib/Hledger/Reports/PostingsReport.hs
index d79deddd5..3024b9877 100644
--- a/hledger-lib/Hledger/Reports/PostingsReport.hs
+++ b/hledger-lib/Hledger/Reports/PostingsReport.hs
@@ -76,7 +76,7 @@ postingsReport ropts@ReportOpts{..} q j =
       styles      = journalCommodityStyles j
       priceoracle = journalPriceOracle infer_value_ j
       multiperiod = interval_ /= NoInterval
-      today       = fromMaybe (error' "postingsReport: could not pick a valuation date, ReportOpts today_ is unset") today_
+      today       = fromMaybe (error' "postingsReport: could not pick a valuation date, ReportOpts today_ is unset") today_  -- PARTIAL:
 
       -- postings to be included in the report, and similarly-matched postings before the report start date
       (precedingps, reportps) = matchedPostingsBeforeAndDuring ropts q j reportspan
@@ -95,7 +95,7 @@ postingsReport ropts@ReportOpts{..} q j =
             where
               mreportlast = reportPeriodLastDay ropts
           reportorjournallast =
-            fromMaybe (error' "postingsReport: expected a non-empty journal") $ -- XXX shouldn't happen
+            fromMaybe (error' "postingsReport: expected a non-empty journal") $  -- PARTIAL: shouldn't happen
             reportPeriodOrJournalLastDay ropts j
 
       -- Posting report items ready for display.
@@ -118,7 +118,7 @@ postingsReport ropts@ReportOpts{..} q j =
                   -- XXX constrain valuation type to AtDate daybeforereportstart here ?
                 where
                   daybeforereportstart =
-                    maybe (error' "postingsReport: expected a non-empty journal") -- XXX shouldn't happen
+                    maybe (error' "postingsReport: expected a non-empty journal")  -- PARTIAL: shouldn't happen
                     (addDays (-1))
                     $ reportPeriodOrJournalStart ropts j
 
diff --git a/hledger-lib/Hledger/Reports/ReportOptions.hs b/hledger-lib/Hledger/Reports/ReportOptions.hs
index dc2069e5e..2ac7c611f 100644
--- a/hledger-lib/Hledger/Reports/ReportOptions.hs
+++ b/hledger-lib/Hledger/Reports/ReportOptions.hs
@@ -327,7 +327,7 @@ intervalFromRawOpts = lastDef NoInterval . collectopts intervalfromrawopt
             (\e -> usageError $ "could not parse period option: "++customErrorBundlePretty e)
             extractIntervalOrNothing $
             parsePeriodExpr
-              (error' "intervalFromRawOpts: did not expect to need today's date here") -- should not happen; we are just getting the interval, which does not use the reference date
+              (error' "intervalFromRawOpts: did not expect to need today's date here")  -- PARTIAL: should not happen; we are just getting the interval, which does not use the reference date
               (stripquotes $ T.pack v)
       | n == "daily"     = Just $ Days 1
       | n == "weekly"    = Just $ Weeks 1
@@ -466,7 +466,7 @@ queryFromOpts :: Day -> ReportOpts -> Query
 queryFromOpts d ropts = simplifyQuery . And $ [flagsq, argsq]
   where
     flagsq = queryFromOptsOnly d ropts
-    argsq = fst $ either error' id $ parseQuery d (T.pack $ query_ ropts)  -- TODO:
+    argsq = fst $ either error' id $ parseQuery d (T.pack $ query_ ropts)  -- PARTIAL:
 
 -- | Convert report options to a query, ignoring any non-flag command line arguments.
 queryFromOptsOnly :: Day -> ReportOpts -> Query
@@ -484,7 +484,7 @@ queryFromOptsOnly _d ReportOpts{..} = simplifyQuery $ And flagsq
 -- | Convert report options and arguments to query options.
 -- If there is a parsing problem, this function calls error.
 queryOptsFromOpts :: Day -> ReportOpts -> [QueryOpt]
-queryOptsFromOpts d = snd . either error' id . parseQuery d . T.pack . query_
+queryOptsFromOpts d = snd . either error' id . parseQuery d . T.pack . query_  -- PARTIAL:
 
 -- Report dates.
 
diff --git a/hledger-lib/Hledger/Utils.hs b/hledger-lib/Hledger/Utils.hs
index fb0c172b4..ab80eef87 100644
--- a/hledger-lib/Hledger/Utils.hs
+++ b/hledger-lib/Hledger/Utils.hs
@@ -162,7 +162,8 @@ applyN n f | n < 1     = id
 expandPath :: FilePath -> FilePath -> IO FilePath -- general type sig for use in reader parsers
 expandPath _ "-" = return "-"
 expandPath curdir p = (if isRelative p then (curdir </>) else id) `liftM` expandHomePath p
-
+-- PARTIAL:
+  
 -- | Expand user home path indicated by tilde prefix
 expandHomePath :: FilePath -> IO FilePath
 expandHomePath = \case
diff --git a/hledger-lib/Hledger/Utils/Parse.hs b/hledger-lib/Hledger/Utils/Parse.hs
index 4854caf7d..82c62195a 100644
--- a/hledger-lib/Hledger/Utils/Parse.hs
+++ b/hledger-lib/Hledger/Utils/Parse.hs
@@ -108,7 +108,7 @@ fromparse
 fromparse = either parseerror id
 
 parseerror :: (Show t, Show (Token t), Show e) => ParseErrorBundle t e -> a
-parseerror e = error' $ showParseError e
+parseerror e = error' $ showParseError e  -- PARTIAL:
 
 showParseError
   :: (Show t, Show (Token t), Show e)
diff --git a/hledger-lib/Hledger/Utils/Regex.hs b/hledger-lib/Hledger/Utils/Regex.hs
index e7c7e850d..d613f3a5d 100644
--- a/hledger-lib/Hledger/Utils/Regex.hs
+++ b/hledger-lib/Hledger/Utils/Regex.hs
@@ -130,6 +130,7 @@ replaceMatch replpat s matchgroups = pre ++ repl ++ post
 replaceBackReference :: MatchText String -> String -> String
 replaceBackReference grps ('\\':s@(_:_)) | all isDigit s =
   case read s of n | n `elem` indices grps -> fst (grps ! n)
+  -- PARTIAL:D
                  _                         -> error' $ "no match group exists for backreference \"\\"++s++"\""
 replaceBackReference _ s = error' $ "replaceBackReference called on non-numeric-backreference \""++s++"\", shouldn't happen"
 
diff --git a/hledger-ui/Hledger/UI/AccountsScreen.hs b/hledger-ui/Hledger/UI/AccountsScreen.hs
index c8f6e1a11..05c5e0b5a 100644
--- a/hledger-ui/Hledger/UI/AccountsScreen.hs
+++ b/hledger-ui/Hledger/UI/AccountsScreen.hs
@@ -116,7 +116,7 @@ asInit d reset ui@UIState{
                         }
 
 
-asInit _ _ _ = error "init function called with wrong screen type, should not happen"
+asInit _ _ _ = error "init function called with wrong screen type, should not happen"  -- PARTIAL:
 
 asDraw :: UIState -> [Widget Name]
 asDraw UIState{aopts=_uopts@UIOpts{cliopts_=copts@CliOpts{reportopts_=ropts}}
@@ -222,7 +222,7 @@ asDraw UIState{aopts=_uopts@UIOpts{cliopts_=copts@CliOpts{reportopts_=ropts}}
               ,("q", str "quit")
               ]
 
-asDraw _ = error "draw function called with wrong screen type, should not happen"
+asDraw _ = error "draw function called with wrong screen type, should not happen"  -- PARTIAL:
 
 asDrawItem :: (Int,Int) -> Bool -> AccountsScreenItem -> Widget Name
 asDrawItem (acctwidth, balwidth) selected AccountsScreenItem{..} =
@@ -393,7 +393,7 @@ asHandle ui0@UIState{
   where
     journalspan = journalDateSpan False j
 
-asHandle _ _ = error "event handler called with wrong screen type, should not happen"
+asHandle _ _ = error "event handler called with wrong screen type, should not happen"  -- PARTIAL:
 
 asSetSelectedAccount a s@AccountsScreen{} = s & asSelectedAccount .~ a
 asSetSelectedAccount _ s = s
diff --git a/hledger-ui/Hledger/UI/ErrorScreen.hs b/hledger-ui/Hledger/UI/ErrorScreen.hs
index f8921bf17..da15b4881 100644
--- a/hledger-ui/Hledger/UI/ErrorScreen.hs
+++ b/hledger-ui/Hledger/UI/ErrorScreen.hs
@@ -41,7 +41,7 @@ errorScreen = ErrorScreen{
 
 esInit :: Day -> Bool -> UIState -> UIState
 esInit _ _ ui@UIState{aScreen=ErrorScreen{}} = ui
-esInit _ _ _ = error "init function called with wrong screen type, should not happen"
+esInit _ _ _ = error "init function called with wrong screen type, should not happen"  -- PARTIAL:
 
 esDraw :: UIState -> [Widget Name]
 esDraw UIState{aopts=UIOpts{cliopts_=copts@CliOpts{}}
@@ -72,7 +72,7 @@ esDraw UIState{aopts=UIOpts{cliopts_=copts@CliOpts{}}
               ,("q", "quit")
               ]
 
-esDraw _ = error "draw function called with wrong screen type, should not happen"
+esDraw _ = error "draw function called with wrong screen type, should not happen"  -- PARTIAL:
 
 esHandle :: UIState -> BrickEvent Name AppEvent -> EventM Name (Next UIState)
 esHandle ui@UIState{aScreen=ErrorScreen{..}
@@ -111,7 +111,7 @@ esHandle ui@UIState{aScreen=ErrorScreen{..}
         VtyEvent (EvKey (KChar 'z') [MCtrl]) -> suspend ui
         _ -> continue ui
 
-esHandle _ _ = error "event handler called with wrong screen type, should not happen"
+esHandle _ _ = error "event handler called with wrong screen type, should not happen"  -- PARTIAL:
 
 -- | Parse the file name, line and column number from a hledger parse error message, if possible.
 -- Temporary, we should keep the original parse error location. XXX
diff --git a/hledger-ui/Hledger/UI/Main.hs b/hledger-ui/Hledger/UI/Main.hs
index f95de60e0..25fe32bb3 100644
--- a/hledger-ui/Hledger/UI/Main.hs
+++ b/hledger-ui/Hledger/UI/Main.hs
@@ -108,7 +108,7 @@ runBrickUi uopts@UIOpts{cliopts_=copts@CliOpts{inputopts_=_iopts,reportopts_=rop
       where
         q = queryFromOpts d ropts
         datespanfromargs = queryDateSpan (date2_ ropts) $ fst $
-                           either error' id $ parseQuery d (T.pack $ query_ ropts)
+                           either error' id $ parseQuery d (T.pack $ query_ ropts)  -- PARTIAL:
         periodfromoptsandargs =
           dateSpanAsPeriod $ spansIntersect [periodAsDateSpan $ period_ ropts, datespanfromargs]
         filteredQueryArg = \case
@@ -130,7 +130,7 @@ runBrickUi uopts@UIOpts{cliopts_=copts@CliOpts{inputopts_=_iopts,reportopts_=rop
       Just apat -> (rsSetAccount acct False registerScreen, [ascr'])
         where
           acct = headDef
-                 (error' $ "--register "++apat++" did not match any account")
+                 (error' $ "--register "++apat++" did not match any account")  -- PARTIAL:
                  $ filter (regexMatches apat . T.unpack) $ journalAccountNames j
           -- Initialising the accounts screen is awkward, requiring
           -- another temporary UIState value..
diff --git a/hledger-ui/Hledger/UI/RegisterScreen.hs b/hledger-ui/Hledger/UI/RegisterScreen.hs
index c4805256a..8a474cb96 100644
--- a/hledger-ui/Hledger/UI/RegisterScreen.hs
+++ b/hledger-ui/Hledger/UI/RegisterScreen.hs
@@ -135,7 +135,7 @@ rsInit d reset ui@UIState{aopts=_uopts@UIOpts{cliopts_=CliOpts{reportopts_=ropts
                 ts = map rsItemTransaction displayitems
         endidx = length displayitems - 1
 
-rsInit _ _ _ = error "init function called with wrong screen type, should not happen"
+rsInit _ _ _ = error "init function called with wrong screen type, should not happen"  -- PARTIAL:
 
 rsDraw :: UIState -> [Widget Name]
 rsDraw UIState{aopts=_uopts@UIOpts{cliopts_=copts@CliOpts{reportopts_=ropts}}
@@ -248,7 +248,7 @@ rsDraw UIState{aopts=_uopts@UIOpts{cliopts_=copts@CliOpts{reportopts_=ropts}}
 --               ,("q", "quit")
               ]
 
-rsDraw _ = error "draw function called with wrong screen type, should not happen"
+rsDraw _ = error "draw function called with wrong screen type, should not happen"  -- PARTIAL:
 
 rsDrawItem :: (Int,Int,Int,Int,Int) -> Bool -> RegisterScreenItem -> Widget Name
 rsDrawItem (datewidth,descwidth,acctswidth,changewidth,balwidth) selected RegisterScreenItem{..} =
@@ -396,7 +396,7 @@ rsHandle ui@UIState{
         MouseDown _ _ _ _ -> continue ui
         MouseUp _ _ _     -> continue ui
 
-rsHandle _ _ = error "event handler called with wrong screen type, should not happen"
+rsHandle _ _ = error "event handler called with wrong screen type, should not happen"  -- PARTIAL:
 
 isBlankElement mel = ((rsItemDate . snd) <$> mel) == Just ""
 
diff --git a/hledger-ui/Hledger/UI/TransactionScreen.hs b/hledger-ui/Hledger/UI/TransactionScreen.hs
index 28ca4de64..ed305b657 100644
--- a/hledger-ui/Hledger/UI/TransactionScreen.hs
+++ b/hledger-ui/Hledger/UI/TransactionScreen.hs
@@ -55,7 +55,7 @@ tsInit _d _reset ui@UIState{aopts=UIOpts{cliopts_=CliOpts{reportopts_=_ropts}}
   --       (acommodity$head$amounts$pamount$head$tpostings$snd$tsTransaction)
   --      `seq`
   ui
-tsInit _ _ _ = error "init function called with wrong screen type, should not happen"
+tsInit _ _ _ = error "init function called with wrong screen type, should not happen"  -- PARTIAL:
 
 tsDraw :: UIState -> [Widget Name]
 tsDraw UIState{aopts=UIOpts{cliopts_=copts@CliOpts{reportopts_=ropts}}
@@ -76,10 +76,10 @@ tsDraw UIState{aopts=UIOpts{cliopts_=copts@CliOpts{reportopts_=ropts}}
         prices = journalPriceOracle (infer_value_ ropts) j
         styles = journalCommodityStyles j
         periodlast =
-          fromMaybe (error' "TransactionScreen: expected a non-empty journal") $ -- XXX shouldn't happen
+          fromMaybe (error' "TransactionScreen: expected a non-empty journal") $  -- PARTIAL: shouldn't happen
           reportPeriodOrJournalLastDay ropts j
         mreportlast = reportPeriodLastDay ropts
-        today = fromMaybe (error' "TransactionScreen: could not pick a valuation date, ReportOpts today_ is unset") $ today_ ropts
+        today = fromMaybe (error' "TransactionScreen: could not pick a valuation date, ReportOpts today_ is unset") $ today_ ropts  -- PARTIAL:
         multiperiod = interval_ ropts /= NoInterval
 
       render $ defaultLayout toplabel bottomlabel $ str $
@@ -126,7 +126,7 @@ tsDraw UIState{aopts=UIOpts{cliopts_=copts@CliOpts{reportopts_=ropts}}
               ,("q", "quit")
               ]
 
-tsDraw _ = error "draw function called with wrong screen type, should not happen"
+tsDraw _ = error "draw function called with wrong screen type, should not happen"  -- PARTIAL:
 
 tsHandle :: UIState -> BrickEvent Name AppEvent -> EventM Name (Next UIState)
 tsHandle ui@UIState{aScreen=s@TransactionScreen{tsTransaction=(i,t)
@@ -204,7 +204,7 @@ tsHandle ui@UIState{aScreen=s@TransactionScreen{tsTransaction=(i,t)
         VtyEvent (EvKey (KChar 'z') [MCtrl]) -> suspend ui
         _ -> continue ui
 
-tsHandle _ _ = error "event handler called with wrong screen type, should not happen"
+tsHandle _ _ = error "event handler called with wrong screen type, should not happen"  -- PARTIAL:
 
 -- Got to redo the register screen's transactions report, to get the latest transactions list for this screen.
 -- XXX Duplicates rsInit. Why do we have to do this as well as regenerateScreens ?
diff --git a/hledger-web/Hledger/Web/Handler/RegisterR.hs b/hledger-web/Hledger/Web/Handler/RegisterR.hs
index 17c8d52a3..d4cca4028 100644
--- a/hledger-web/Hledger/Web/Handler/RegisterR.hs
+++ b/hledger-web/Hledger/Web/Handler/RegisterR.hs
@@ -86,7 +86,7 @@ undecorateLinks xs0@(x:_) =
             let (link, xs1) = span (isJust . fst) xs0
                 (comma, xs2) = span (isNothing . fst) xs1
             in (acct, (map snd link, map snd comma)) : undecorateLinks xs2
-        _ -> error "link name not decorated with account"
+        _ -> error "link name not decorated with account"  -- PARTIAL:
 
 decorateLinks :: [(acct, ([char], [char]))] -> [(Maybe acct, char)]
 decorateLinks =
diff --git a/hledger-web/Hledger/Web/WebOptions.hs b/hledger-web/Hledger/Web/WebOptions.hs
index 649044242..b700778a0 100644
--- a/hledger-web/Hledger/Web/WebOptions.hs
+++ b/hledger-web/Hledger/Web/WebOptions.hs
@@ -134,7 +134,7 @@ rawOptsToWebOpts rawopts =
           maybestringopt "base-url" rawopts
         caps' = join $ T.splitOn "," . T.pack <$> listofstringopt "capabilities" rawopts
         caps = case traverse capabilityFromText caps' of
-          Left e -> error' ("Unknown capability: " ++ T.unpack e)
+          Left e -> error' ("Unknown capability: " ++ T.unpack e)  -- PARTIAL:
           Right [] -> [CapView, CapAdd]
           Right xs -> xs
         sock = stripTrailingSlash <$> maybestringopt "socket" rawopts
diff --git a/hledger-web/Hledger/Web/Widget/AddForm.hs b/hledger-web/Hledger/Web/Widget/AddForm.hs
index fc60b9c06..7119aaec0 100644
--- a/hledger-web/Hledger/Web/Widget/AddForm.hs
+++ b/hledger-web/Hledger/Web/Widget/AddForm.hs
@@ -91,7 +91,7 @@ addForm j today = identifyForm "add" $ \extra -> do
 
     listField = Field
       { fieldParse = const . pure . Right . Just . dropWhileEnd T.null
-      , fieldView = error "Don't render using this!"
+      , fieldView = error "Don't render using this!"  -- PARTIAL:
       , fieldEnctype = UrlEncoded
       }
 
diff --git a/hledger/Hledger/Cli/CliOptions.hs b/hledger/Hledger/Cli/CliOptions.hs
index 8916342fb..8e4ebfc22 100644
--- a/hledger/Hledger/Cli/CliOptions.hs
+++ b/hledger/Hledger/Cli/CliOptions.hs
@@ -323,7 +323,7 @@ hledgerCommandMode :: CommandDoc -> [Flag RawOpts] -> [(String, [Flag RawOpts])]
   -> [Flag RawOpts] -> ([Arg RawOpts], Maybe (Arg RawOpts)) -> Mode RawOpts
 hledgerCommandMode doc unnamedflaggroup namedflaggroups hiddenflaggroup argsdescr =
   case parseCommandDoc doc of
-    Nothing -> error' $ "Could not parse command doc:\n"++doc++"\n"
+    Nothing -> error' $ "Could not parse command doc:\n"++doc++"\n"  -- PARTIAL:
     Just (names, shorthelp, longhelplines) ->
       (defCommandMode names) {
          modeHelp        = shorthelp
diff --git a/hledger/Hledger/Cli/Commands.hs b/hledger/Hledger/Cli/Commands.hs
index d9d3ba858..e3ba51d8d 100644
--- a/hledger/Hledger/Cli/Commands.hs
+++ b/hledger/Hledger/Cli/Commands.hs
@@ -304,7 +304,7 @@ tests_Commands = tests "Commands" [
         let
           ignoresourcepos j = j{jtxns=map (\t -> t{tsourcepos=nullsourcepos}) (jtxns j)}
           sameParse str1 str2 = do
-            j1 <- readJournal def Nothing str1 >>= either error' (return . ignoresourcepos)
+            j1 <- readJournal def Nothing str1 >>= either error' (return . ignoresourcepos)  -- PARTIAL:
             j2 <- readJournal def Nothing str2 >>= either error' (return . ignoresourcepos)
             j1 @?= j2{jlastreadtime=jlastreadtime j1, jfiles=jfiles j1} --, jparsestate=jparsestate j1}
         sameParse
@@ -322,19 +322,19 @@ tests_Commands = tests "Commands" [
            )
 
     ,test "preserves \"virtual\" posting type" $ do
-      j <- readJournal def Nothing "apply account test\n2008/12/07 One\n  (from)  $-1\n  (to)  $1\n" >>= either error' return
+      j <- readJournal def Nothing "apply account test\n2008/12/07 One\n  (from)  $-1\n  (to)  $1\n" >>= either error' return  -- PARTIAL:
       let p = head $ tpostings $ head $ jtxns j
       paccount p @?= "test:from"
       ptype p @?= VirtualPosting
     ]
 
   ,test "alias directive" $ do
-    j <- readJournal def Nothing "!alias expenses = equity:draw:personal\n1/1\n (expenses:food)  1\n" >>= either error' return
+    j <- readJournal def Nothing "!alias expenses = equity:draw:personal\n1/1\n (expenses:food)  1\n" >>= either error' return  -- PARTIAL:
     let p = head $ tpostings $ head $ jtxns j
     paccount p @?= "equity:draw:personal:food"
 
   ,test "Y default year directive" $ do
-    j <- readJournal def Nothing defaultyear_journal_txt >>= either error' return
+    j <- readJournal def Nothing defaultyear_journal_txt >>= either error' return  -- PARTIAL:
     tdate (head $ jtxns j) @?= fromGregorian 2009 1 1
 
   ,test "ledgerAccountNames" $
diff --git a/hledger/Hledger/Cli/Commands/Add.hs b/hledger/Hledger/Cli/Commands/Add.hs
index 22e3057ad..ca190b90b 100644
--- a/hledger/Hledger/Cli/Commands/Add.hs
+++ b/hledger/Hledger/Cli/Commands/Add.hs
@@ -121,7 +121,7 @@ getAndAddTransactions es@EntryState{..} = (do
   let defaultPrevInput = PrevInput{prevDateAndCode=Nothing, prevDescAndCmnt=Nothing, prevAccount=[], prevAmountAndCmnt=[]}
   mt <- runInputT (setComplete noCompletion defaultSettings) (System.Console.Wizard.run $ haskeline $ confirmedTransactionWizard defaultPrevInput es [])
   case mt of
-    Nothing -> error "Could not interpret the input, restarting"  -- caught below causing a restart, I believe
+    Nothing -> error "Could not interpret the input, restarting"  -- caught below causing a restart, I believe  -- PARTIAL:
     Just t -> do
       j <- if debug_ esOpts > 0
            then do hPrintf stderr "Skipping journal add due to debug mode.\n"
diff --git a/hledger/Hledger/Cli/Commands/Aregister.hs b/hledger/Hledger/Cli/Commands/Aregister.hs
index 3d9757d6a..cd84899c4 100644
--- a/hledger/Hledger/Cli/Commands/Aregister.hs
+++ b/hledger/Hledger/Cli/Commands/Aregister.hs
@@ -74,10 +74,10 @@ aregister opts@CliOpts{rawopts_=rawopts,reportopts_=ropts} j = do
   d <- getCurrentDay
   -- the first argument specifies the account, any remaining arguments are a filter query
   let args' = listofstringopt "args" rawopts
-  when (null args') $ error' "aregister needs an account, please provide an account name or pattern"
+  when (null args') $ error' "aregister needs an account, please provide an account name or pattern"  -- PARTIAL:
   let
     (apat:queryargs) = args'
-    acct = headDef (error' $ show apat++" did not match any account") $
+    acct = headDef (error' $ show apat++" did not match any account") $  -- PARTIAL:
            filter (regexMatches apat . T.unpack) $ journalAccountNames j
     -- gather report options
     inclusive = True  -- tree_ ropts
@@ -108,7 +108,7 @@ aregister opts@CliOpts{rawopts_=rawopts,reportopts_=ropts} j = do
     render | fmt=="json" = (++"\n") . T.unpack . TL.toStrict . encodeToLazyText . toJSON
            | fmt=="csv"  = (++"\n") . printCSV . accountTransactionsReportAsCsv reportq thisacctq
            | fmt=="txt"  = accountTransactionsReportAsText opts reportq thisacctq
-           | otherwise   = const $ error' $ unsupportedOutputFormatError fmt
+           | otherwise   = const $ error' $ unsupportedOutputFormatError fmt  -- PARTIAL:
       where
         fmt = outputFormatFromOpts opts
 
diff --git a/hledger/Hledger/Cli/Commands/Balance.hs b/hledger/Hledger/Cli/Commands/Balance.hs
index 881c4ede2..843197185 100644
--- a/hledger/Hledger/Cli/Commands/Balance.hs
+++ b/hledger/Hledger/Cli/Commands/Balance.hs
@@ -304,6 +304,7 @@ balancemode = hledgerCommandMode
 -- | The balance command, prints a balance report.
 balance :: CliOpts -> Journal -> IO ()
 balance opts@CliOpts{rawopts_=rawopts,reportopts_=ropts@ReportOpts{..}} j = do
+  -- PARTIAL:
   d <- getCurrentDay
   case lineFormatFromOpts ropts of
     Left err -> error' $ unlines [err]
@@ -494,7 +495,7 @@ multiBalanceReportAsHtml ropts mbr =
 multiBalanceReportHtmlRows :: ReportOpts -> MultiBalanceReport -> (Html (), [Html ()], Maybe (Html ()))
 multiBalanceReportHtmlRows ropts mbr =
   let
-    headingsrow:rest | transpose_ ropts = error' "Sorry, --transpose is not supported with HTML output yet"
+    headingsrow:rest | transpose_ ropts = error' "Sorry, --transpose is not supported with HTML output yet"  -- PARTIAL:
                      | otherwise = multiBalanceReportAsCsv ropts mbr
     (bodyrows, mtotalsrow) | no_total_ ropts = (rest,      Nothing)
                            | otherwise       = (init rest, Just $ last rest)
@@ -581,7 +582,7 @@ multiBalanceReportAsText ropts@ReportOpts{..} r =
       (showDateSpan $ periodicReportSpan r)
       (case value_ of
         Just (AtCost _mc)   -> ", valued at cost"
-        Just (AtThen _mc)   -> error' unsupportedValueThenError  -- TODO -- ", valued at period ends"  -- handled like AtEnd for now
+        Just (AtThen _mc)   -> error' unsupportedValueThenError  -- TODO -- ", valued at period ends"  -- handled like AtEnd for now  -- PARTIAL:
         Just (AtEnd _mc)    -> ", valued at period ends"
         Just (AtNow _mc)    -> ", current value"
         -- XXX duplicates the above
diff --git a/hledger/Hledger/Cli/Commands/Diff.hs b/hledger/Hledger/Cli/Commands/Diff.hs
index 8750e4071..aa5bfb64f 100644
--- a/hledger/Hledger/Cli/Commands/Diff.hs
+++ b/hledger/Hledger/Cli/Commands/Diff.hs
@@ -87,7 +87,7 @@ matching ppl ppr = do
 
 readJournalFile' :: FilePath -> IO Journal
 readJournalFile' fn =
-    readJournalFile definputopts {ignore_assertions_ = True} fn >>= either error' return
+    readJournalFile definputopts {ignore_assertions_ = True} fn >>= either error' return  -- PARTIAL:
 
 matchingPostings :: AccountName -> Journal -> [PostingWithPath]
 matchingPostings acct j = filter ((== acct) . paccount . ppposting) $ allPostingsWithPath j
diff --git a/hledger/Hledger/Cli/Commands/Import.hs b/hledger/Hledger/Cli/Commands/Import.hs
index b83704ef2..9598b3725 100755
--- a/hledger/Hledger/Cli/Commands/Import.hs
+++ b/hledger/Hledger/Cli/Commands/Import.hs
@@ -34,7 +34,7 @@ importcmd opts@CliOpts{rawopts_=rawopts,inputopts_=iopts} j = do
     dryrun = boolopt "dry-run" rawopts
     iopts' = iopts{new_=True, new_save_=not dryrun}
   case inputfiles of
-    [] -> error' "please provide one or more input files as arguments"
+    [] -> error' "please provide one or more input files as arguments"  -- PARTIAL:
     fs -> do
       enewj <- readJournalFiles iopts' fs
       case enewj of
diff --git a/hledger/Hledger/Cli/Commands/Print.hs b/hledger/Hledger/Cli/Commands/Print.hs
index 4317192f2..aa5272091 100644
--- a/hledger/Hledger/Cli/Commands/Print.hs
+++ b/hledger/Hledger/Cli/Commands/Print.hs
@@ -62,7 +62,7 @@ printEntries opts@CliOpts{reportopts_=ropts} j = do
         "csv"  -> (++"\n") . printCSV . entriesReportAsCsv
         "json" -> (++"\n") . TL.unpack . toJsonText
         "sql"  -> entriesReportAsSql
-        _      -> const $ error' $ unsupportedOutputFormatError fmt
+        _      -> const $ error' $ unsupportedOutputFormatError fmt  -- PARTIAL:
   writeOutput opts $ render $ entriesReport ropts q j
 
 entriesReportAsText :: CliOpts -> EntriesReport -> String
diff --git a/hledger/Hledger/Cli/Commands/Register.hs b/hledger/Hledger/Cli/Commands/Register.hs
index 5f3233dd7..eed3be41d 100644
--- a/hledger/Hledger/Cli/Commands/Register.hs
+++ b/hledger/Hledger/Cli/Commands/Register.hs
@@ -64,7 +64,7 @@ register opts@CliOpts{reportopts_=ropts} j = do
       render | fmt=="txt"  = postingsReportAsText
              | fmt=="csv"  = const ((++"\n") . printCSV . postingsReportAsCsv)
              | fmt=="json" = const ((++"\n") . TL.unpack . toJsonText)
-             | otherwise   = const $ error' $ unsupportedOutputFormatError fmt
+             | otherwise   = const $ error' $ unsupportedOutputFormatError fmt  -- PARTIAL:
   writeOutput opts $ render opts $ postingsReport ropts (queryFromOpts d ropts) j
 
 postingsReportAsCsv :: PostingsReport -> CSV
diff --git a/hledger/Hledger/Cli/Commands/Rewrite.hs b/hledger/Hledger/Cli/Commands/Rewrite.hs
index 56d7f9a88..7c481fb12 100755
--- a/hledger/Hledger/Cli/Commands/Rewrite.hs
+++ b/hledger/Hledger/Cli/Commands/Rewrite.hs
@@ -40,7 +40,7 @@ rewrite opts@CliOpts{rawopts_=rawopts,reportopts_=ropts} j@Journal{jtxns=ts} = d
   -- rewrite matched transactions
   d <- getCurrentDay
   let modifiers = transactionModifierFromOpts opts : jtxnmodifiers j
-  let j' = j{jtxns=either error' id $ modifyTransactions d modifiers ts}
+  let j' = j{jtxns=either error' id $ modifyTransactions d modifiers ts}  -- PARTIAL:
   -- run the print command, showing all transactions, or show diffs
   printOrDiff rawopts opts{reportopts_=ropts{query_=""}} j j'
 
@@ -52,7 +52,7 @@ transactionModifierFromOpts CliOpts{rawopts_=rawopts,reportopts_=ropts} =
   where
     q = T.pack $ query_ ropts
     ps = map (parseposting . T.pack) $ listofstringopt "add-posting" rawopts
-    parseposting t = either (error' . errorBundlePretty) id ep
+    parseposting t = either (error' . errorBundlePretty) id ep  -- PARTIAL:
       where
         ep = runIdentity (runJournalParser (postingp Nothing <* eof) t')
         t' = " " <> t <> "\n" -- inject space and newline for proper parsing
diff --git a/hledger/Hledger/Cli/Commands/Roi.hs b/hledger/Hledger/Cli/Commands/Roi.hs
index fd56ea43c..2da60360b 100644
--- a/hledger/Hledger/Cli/Commands/Roi.hs
+++ b/hledger/Hledger/Cli/Commands/Roi.hs
@@ -214,7 +214,7 @@ internalRateOfReturn showCashFlow prettyTables (OneSpan spanBegin spanEnd valueB
 #endif
         (0.000000000001,10000) (interestSum spanEnd totalCF) of
         Root rate -> return ((rate-1)*100)
-        NotBracketed -> error' "Error: No solution -- not bracketed."
+        NotBracketed -> error' "Error: No solution -- not bracketed."  -- PARTIAL:
         SearchFailed -> error' "Error: Failed to find solution."
 
 type CashFlow = [(Day, Quantity)]
@@ -236,5 +236,5 @@ unMix :: MixedAmount -> Quantity
 unMix a =
   case (normaliseMixedAmount $ mixedAmountCost a) of
     (Mixed [a]) -> aquantity a
-    _ -> error' "MixedAmount failed to normalize"
+    _ -> error' "MixedAmount failed to normalize"  -- PARTIAL:
 
diff --git a/hledger/Hledger/Cli/Commands/Stats.hs b/hledger/Hledger/Cli/Commands/Stats.hs
index b4c16c187..88d7fb333 100644
--- a/hledger/Hledger/Cli/Commands/Stats.hs
+++ b/hledger/Hledger/Cli/Commands/Stats.hs
@@ -82,7 +82,7 @@ showLedgerStats l today span =
              path = journalFilePath j
              ts = sortOn tdate $ filter (spanContainsDate span . tdate) $ jtxns j
              as = nub $ map paccount $ concatMap tpostings ts
-             cs = either error' Map.keys $ commodityStylesFromAmounts $ concatMap (amounts . pamount) $ concatMap tpostings ts
+             cs = either error' Map.keys $ commodityStylesFromAmounts $ concatMap (amounts . pamount) $ concatMap tpostings ts  -- PARTIAL:
              lastdate | null ts = Nothing
                       | otherwise = Just $ tdate $ last ts
              lastelapsed = fmap (diffDays today) lastdate
diff --git a/hledger/Hledger/Cli/Main.hs b/hledger/Hledger/Cli/Main.hs
index 80e74e36b..e7203a0ed 100644
--- a/hledger/Hledger/Cli/Main.hs
+++ b/hledger/Hledger/Cli/Main.hs
@@ -140,7 +140,7 @@ main = do
     hasVersion           = ("--version" `elem`)
     hasDetailedVersion   = ("--version+" `elem`)
     printUsage           = putStr $ showModeUsage $ mainmode addons
-    badCommandError      = error' ("command "++rawcmd++" is not recognized, run with no command to see a list") >> exitFailure
+    badCommandError      = error' ("command "++rawcmd++" is not recognized, run with no command to see a list") >> exitFailure  -- PARTIAL:
     hasHelpFlag args     = any (`elem` args) ["-h","--help"]
     f `orShowHelp` mode
       | hasHelpFlag args = putStr $ showModeUsage mode
diff --git a/hledger/Hledger/Cli/Utils.hs b/hledger/Hledger/Cli/Utils.hs
index b38681f0c..8261cba2e 100644
--- a/hledger/Hledger/Cli/Utils.hs
+++ b/hledger/Hledger/Cli/Utils.hs
@@ -73,7 +73,7 @@ withJournalDo opts cmd = do
   journalpaths <- journalFilePathFromOpts opts
   readJournalFiles (inputopts_ opts) journalpaths
   >>= mapM (journalTransform opts)
-  >>= either error' cmd
+  >>= either error' cmd  -- PARTIAL:
 
 -- | Apply some extra post-parse transformations to the journal, if
 -- specified by options. These happen after journal validation, but
@@ -139,7 +139,7 @@ journalAddForecast CliOpts{inputopts_=iopts, reportopts_=ropts} j = do
                        ]
       -- With --auto enabled, transaction modifiers are also applied to forecast txns
       forecasttxns' =
-        (if auto_ iopts then either error' id . modifyTransactions today (jtxnmodifiers j) else id)
+        (if auto_ iopts then either error' id . modifyTransactions today (jtxnmodifiers j) else id)  -- PARTIAL:
         forecasttxns
 
   return $
@@ -150,7 +150,7 @@ journalAddForecast CliOpts{inputopts_=iopts, reportopts_=ropts} j = do
     journalBalanceTransactions' iopts j =
       let assrt = not . ignore_assertions_ $ iopts
       in
-       either error' id $ journalBalanceTransactions assrt j
+       either error' id $ journalBalanceTransactions assrt j  -- PARTIAL:
 
 -- | Write some output to stdout or to a file selected by --output-file.
 -- If the file exists it will be overwritten.
diff --git a/hledger/Hledger/Cli/Version.hs b/hledger/Hledger/Cli/Version.hs
index 2e73f28a7..b762690b3 100644
--- a/hledger/Hledger/Cli/Version.hs
+++ b/hledger/Hledger/Cli/Version.hs
@@ -63,5 +63,5 @@ binaryfilename progname = prettify $ splitAtElement '.' buildversion
                   prettify (major:minor:bugfix:[]) = prettify [major,minor,bugfix,"0"]
                   prettify (major:minor:[])        = prettify [major,minor,"0","0"]
                   prettify (major:[])              = prettify [major,"0","0","0"]
-                  prettify []                      = error' "VERSION is empty, please fix"
+                  prettify []                      = error' "VERSION is empty, please fix"  -- PARTIAL:
                   prettify _                       = error' "VERSION has too many components, please fix"
diff --git a/hledger/bench/bench.hs b/hledger/bench/bench.hs
index 3df512aac..e63914b45 100644
--- a/hledger/bench/bench.hs
+++ b/hledger/bench/bench.hs
@@ -34,7 +34,7 @@ main = do
 benchWithTimeit = do
   getCurrentDirectory >>= printf "Benchmarking hledger in %s with timeit\n"
   let opts = defcliopts{output_file_=Just outputfile}
-  (t0,j) <- timeit ("read "++inputfile) $ either error id <$> readJournalFile def inputfile
+  (t0,j) <- timeit ("read "++inputfile) $ either error id <$> readJournalFile def inputfile  -- PARTIAL:
   (t1,_) <- timeit ("print") $ print' opts j
   (t2,_) <- timeit ("register") $ register opts j
   (t3,_) <- timeit ("balance") $ balance  opts j
@@ -50,9 +50,9 @@ timeit name action = do
 benchWithCriterion = do
   getCurrentDirectory >>= printf "Benchmarking hledger in %s with criterion\n"
   let opts = defcliopts{output_file_=Just "/dev/null"}
-  j <- either error id <$> readJournalFile def inputfile
+  j <- either error id <$> readJournalFile def inputfile  -- PARTIAL:
   Criterion.Main.defaultMainWith defaultConfig $ [
-    bench ("read "++inputfile) $ nfIO $ (either error const <$> readJournalFile def inputfile),
+    bench ("read "++inputfile) $ nfIO $ (either error const <$> readJournalFile def inputfile),  -- PARTIAL:
     bench ("print")            $ nfIO $ print'   opts j,
     bench ("register")         $ nfIO $ register opts j,
     bench ("balance")          $ nfIO $ balance  opts j,