300 lines
11 KiB
Haskell
300 lines
11 KiB
Haskell
{-# LANGUAGE StandaloneDeriving #-}
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{-|
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An 'Amount' is some quantity of money, shares, or anything else.
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A simple amount is a 'Commodity', quantity pair:
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@
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$1
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£-50
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EUR 3.44
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GOOG 500
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1.5h
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90 apples
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0
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@
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An amount may also have a per-unit price, or conversion rate, in terms
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of some other commodity. If present, this is displayed after \@:
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@
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EUR 3 \@ $1.35
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@
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A 'MixedAmount' is zero or more simple amounts. Mixed amounts are
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usually normalised so that there is no more than one amount in each
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commodity, and no zero amounts (or, there is just a single zero amount
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and no others.):
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@
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$50 + EUR 3
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16h + $13.55 + AAPL 500 + 6 oranges
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0
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@
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We can do limited arithmetic with simple or mixed amounts: either
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price-preserving arithmetic with similarly-priced amounts, or
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price-discarding arithmetic which ignores and discards prices.
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-}
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module Ledger.Amount
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where
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import Ledger.Utils
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import Ledger.Types
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import Ledger.Commodity
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instance Show Amount where show = showAmount
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instance Show MixedAmount where show = showMixedAmount
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deriving instance Show HistoricalPrice
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instance Num Amount where
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abs (Amount c q p) = Amount c (abs q) p
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signum (Amount c q p) = Amount c (signum q) p
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fromInteger i = Amount (comm "") (fromInteger i) Nothing
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(+) = amountop (+)
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(-) = amountop (-)
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(*) = amountop (*)
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instance Ord Amount where
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compare (Amount ac aq ap) (Amount bc bq bp) = compare (ac,aq,ap) (bc,bq,bp)
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instance Num MixedAmount where
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fromInteger i = Mixed [Amount (comm "") (fromInteger i) Nothing]
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negate (Mixed as) = Mixed $ map negateAmountPreservingPrice as
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(+) (Mixed as) (Mixed bs) = normaliseMixedAmount $ Mixed $ as ++ bs
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(*) = error "programming error, mixed amounts do not support multiplication"
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abs = error "programming error, mixed amounts do not support abs"
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signum = error "programming error, mixed amounts do not support signum"
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instance Ord MixedAmount where
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compare (Mixed as) (Mixed bs) = compare as bs
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negateAmountPreservingPrice a = (-a){price=price a}
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-- | Apply a binary arithmetic operator to two amounts, converting to the
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-- second one's commodity (and display precision), discarding any price
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-- information. (Using the second commodity is best since sum and other
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-- folds start with a no-commodity amount.)
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amountop :: (Double -> Double -> Double) -> Amount -> Amount -> Amount
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amountop op a@(Amount _ _ _) (Amount bc bq _) =
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Amount bc (quantity (convertAmountTo bc a) `op` bq) Nothing
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-- | Convert an amount to the specified commodity using the appropriate
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-- exchange rate (which is currently always 1).
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convertAmountTo :: Commodity -> Amount -> Amount
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convertAmountTo c2 (Amount c1 q _) = Amount c2 (q * conversionRate c1 c2) Nothing
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-- | Convert mixed amount to the specified commodity
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convertMixedAmountTo :: Commodity -> MixedAmount -> Amount
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convertMixedAmountTo c2 (Mixed ams) = Amount c2 total Nothing
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where
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total = sum . map (quantity . convertAmountTo c2) $ ams
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-- | Convert an amount to the commodity of its saved price, if any.
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costOfAmount :: Amount -> Amount
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costOfAmount a@(Amount _ _ Nothing) = a
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costOfAmount (Amount _ q (Just price))
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| isZeroMixedAmount price = nullamt
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| otherwise = Amount pc (pq*q) Nothing
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where (Amount pc pq _) = head $ amounts price
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-- | Get the string representation of an amount, based on its commodity's
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-- display settings.
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showAmount :: Amount -> String
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showAmount (Amount (Commodity {symbol="AUTO"}) _ _) = "" -- can appear in an error message
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showAmount a@(Amount (Commodity {symbol=sym,side=side,spaced=spaced}) _ pri) =
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case side of
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L -> printf "%s%s%s%s" sym space quantity price
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R -> printf "%s%s%s%s" quantity space sym price
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where
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space = if spaced then " " else ""
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quantity = showAmount' a
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price = case pri of (Just pamt) -> " @ " ++ showMixedAmount pamt
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Nothing -> ""
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-- XXX refactor
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-- | Get the unambiguous string representation of an amount, for debugging.
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showAmountDebug :: Amount -> String
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showAmountDebug (Amount c q pri) = printf "Amount {commodity = %s, quantity = %s, price = %s}"
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(show c) (show q) (maybe "" showMixedAmountDebug pri)
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-- | Get the string representation of an amount, without any \@ price.
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showAmountWithoutPrice :: Amount -> String
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showAmountWithoutPrice a = showAmount a{price=Nothing}
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-- | Get the string representation (of the number part of) of an amount
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showAmount' :: Amount -> String
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showAmount' (Amount (Commodity {comma=comma,precision=p}) q _) = quantity
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where
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quantity = commad $ printf ("%."++show p++"f") q
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commad = if comma then punctuatethousands else id
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-- | Add thousands-separating commas to a decimal number string
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punctuatethousands :: String -> String
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punctuatethousands s =
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sign ++ addcommas int ++ frac
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where
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(sign,num) = break isDigit s
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(int,frac) = break (=='.') num
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addcommas = reverse . concat . intersperse "," . triples . reverse
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triples [] = []
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triples l = take 3 l : triples (drop 3 l)
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-- | Does this amount appear to be zero when displayed with its given precision ?
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isZeroAmount :: Amount -> Bool
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isZeroAmount = null . filter (`elem` "123456789") . showAmountWithoutPrice
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-- | Is this amount "really" zero, regardless of the display precision ?
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-- Since we are using floating point, for now just test to some high precision.
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isReallyZeroAmount :: Amount -> Bool
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isReallyZeroAmount = null . filter (`elem` "123456789") . printf "%.10f" . quantity
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-- | Access a mixed amount's components.
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amounts :: MixedAmount -> [Amount]
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amounts (Mixed as) = as
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-- | Does this mixed amount appear to be zero - empty, or
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-- containing only simple amounts which appear to be zero ?
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isZeroMixedAmount :: MixedAmount -> Bool
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isZeroMixedAmount = all isZeroAmount . amounts . normaliseMixedAmount
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-- | Is this mixed amount "really" zero ? See isReallyZeroAmount.
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isReallyZeroMixedAmount :: MixedAmount -> Bool
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isReallyZeroMixedAmount = all isReallyZeroAmount . amounts . normaliseMixedAmount
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-- | Is this mixed amount "really" zero, after converting to cost
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-- commodities where possible ?
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isReallyZeroMixedAmountCost :: MixedAmount -> Bool
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isReallyZeroMixedAmountCost = isReallyZeroMixedAmount . costOfMixedAmount
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-- | MixedAmount derives Eq in Types.hs, but that doesn't know that we
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-- want $0 = EUR0 = 0. Yet we don't want to drag all this code in there.
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-- When zero equality is important, use this, for now; should be used
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-- everywhere.
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mixedAmountEquals :: MixedAmount -> MixedAmount -> Bool
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mixedAmountEquals a b = amounts a' == amounts b' || (isZeroMixedAmount a' && isZeroMixedAmount b')
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where a' = normaliseMixedAmount a
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b' = normaliseMixedAmount b
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-- | Get the string representation of a mixed amount, showing each of
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-- its component amounts. NB a mixed amount can have an empty amounts
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-- list in which case it shows as \"\".
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showMixedAmount :: MixedAmount -> String
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showMixedAmount m = vConcatRightAligned $ map show $ amounts $ normaliseMixedAmount m
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-- | Get an unambiguous string representation of a mixed amount for debugging.
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showMixedAmountDebug :: MixedAmount -> String
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showMixedAmountDebug m = printf "Mixed [%s]" as
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where as = intercalate "\n " $ map showAmountDebug $ amounts $ normaliseMixedAmount m
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-- | Get the string representation of a mixed amount, but without
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-- any \@ prices.
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showMixedAmountWithoutPrice :: MixedAmount -> String
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showMixedAmountWithoutPrice m = concat $ intersperse "\n" $ map showfixedwidth as
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where
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(Mixed as) = normaliseMixedAmountIgnoringPrice m
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width = maximum $ map (length . show) as
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showfixedwidth = printf (printf "%%%ds" width) . showAmountWithoutPrice
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-- | Get the string representation of a mixed amount, and if it
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-- appears to be all zero just show a bare 0, ledger-style.
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showMixedAmountOrZero :: MixedAmount -> String
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showMixedAmountOrZero a
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| isZeroMixedAmount a = "0"
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| otherwise = showMixedAmount a
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-- | Get the string representation of a mixed amount, or a bare 0,
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-- without any \@ prices.
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showMixedAmountOrZeroWithoutPrice :: MixedAmount -> String
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showMixedAmountOrZeroWithoutPrice a
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| isZeroMixedAmount a = "0"
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| otherwise = showMixedAmountWithoutPrice a
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-- | Simplify a mixed amount by combining any component amounts which have
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-- the same commodity and the same price. Also removes zero amounts,
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-- or adds a single zero amount if there are no amounts at all.
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normaliseMixedAmount :: MixedAmount -> MixedAmount
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normaliseMixedAmount (Mixed as) = Mixed as''
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where
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as'' = map sumSamePricedAmountsPreservingPrice $ group $ sort as'
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sort = sortBy cmpsymbolandprice
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cmpsymbolandprice a1 a2 = compare (sym a1,price a1) (sym a2,price a2)
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group = groupBy samesymbolandprice
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samesymbolandprice a1 a2 = (sym a1 == sym a2) && (price a1 == price a2)
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sym = symbol . commodity
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as' | null nonzeros = [head $ zeros ++ [nullamt]]
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| otherwise = nonzeros
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(zeros,nonzeros) = partition isReallyZeroAmount as
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sumSamePricedAmountsPreservingPrice [] = nullamt
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sumSamePricedAmountsPreservingPrice as = (sum as){price=price $ head as}
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-- | Simplify a mixed amount by combining any component amounts which have
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-- the same commodity, ignoring and discarding their unit prices if any.
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-- Also removes zero amounts, or adds a single zero amount if there are no
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-- amounts at all.
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normaliseMixedAmountIgnoringPrice :: MixedAmount -> MixedAmount
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normaliseMixedAmountIgnoringPrice (Mixed as) = Mixed as''
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where
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as'' = map sumAmountsDiscardingPrice $ group $ sort as'
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group = groupBy samesymbol where samesymbol a1 a2 = sym a1 == sym a2
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sort = sortBy (comparing sym)
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sym = symbol . commodity
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as' | null nonzeros = [head $ zeros ++ [nullamt]]
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| otherwise = nonzeros
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where (zeros,nonzeros) = partition isZeroAmount as
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sumAmountsDiscardingPrice [] = nullamt
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sumAmountsDiscardingPrice as = (sum as){price=Nothing}
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-- | Convert a mixed amount's component amounts to the commodity of their
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-- saved price, if any.
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costOfMixedAmount :: MixedAmount -> MixedAmount
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costOfMixedAmount (Mixed as) = Mixed $ map costOfAmount as
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-- | The empty simple amount.
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nullamt :: Amount
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nullamt = Amount unknown 0 Nothing
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-- | The empty mixed amount.
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nullmixedamt :: MixedAmount
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nullmixedamt = Mixed []
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-- | A temporary value for parsed transactions which had no amount specified.
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missingamt :: MixedAmount
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missingamt = Mixed [Amount Commodity {symbol="AUTO",side=L,spaced=False,comma=False,precision=0} 0 Nothing]
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tests_Amount = TestList [
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"showMixedAmount" ~: do
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showMixedAmount (Mixed []) ~?= "0"
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,"amount arithmetic" ~: do
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let a1 = dollars 1.23
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let a2 = Amount (comm "$") (-1.23) Nothing
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let a3 = Amount (comm "$") (-1.23) Nothing
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(a1 + a2) `is` Amount (comm "$") 0 Nothing
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(a1 + a3) `is` Amount (comm "$") 0 Nothing
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(a2 + a3) `is` Amount (comm "$") (-2.46) Nothing
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(a3 + a3) `is` Amount (comm "$") (-2.46) Nothing
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sum [a2,a3] `is` Amount (comm "$") (-2.46) Nothing
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sum [a3,a3] `is` Amount (comm "$") (-2.46) Nothing
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sum [a1,a2,a3,-a3] `is` Amount (comm "$") 0 Nothing
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let dollar0 = dollar{precision=0}
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(sum [Amount dollar 1.25 Nothing, Amount dollar0 (-1) Nothing, Amount dollar (-0.25) Nothing])
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`is` (Amount dollar 0 Nothing)
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,"mixed amount arithmetic" ~: do
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let dollar0 = dollar{precision=0}
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(sum $ map (Mixed . (\a -> [a]))
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[Amount dollar 1.25 Nothing,
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Amount dollar0 (-1) Nothing,
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Amount dollar (-0.25) Nothing])
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`is` Mixed [Amount dollar 0 Nothing]
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]
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