hledger/Amount.hs
2007-07-03 19:01:13 +00:00

84 lines
2.0 KiB
Haskell

module Amount
where
import Utils
import Types
import Currency
{-
a simple amount is a currency, quantity pair:
$1
£-50
EUR 3.44
GOOG 500
1.5h
90m
0
a mixed amount is one or more simple amounts:
$50, EUR 3, AAPL 500
16h, $13.55, oranges 6
arithmetic:
$1 - $5 = $-4
$1 + EUR 0.76 = $2
EUR0.76 + $1 = EUR 1.52
EUR0.76 - $1 = 0
($5, 2h) + $1 = ($6, 2h)
($50, EUR 3, AAPL 500) + ($13.55, oranges 6) = $67.51, AAPL 500, oranges 6
($50, EUR 3) * $-1 = $-53.96
($50, AAPL 500) * $-1 = error
-}
tests = runTestTT $ test [
show (dollars 1) ~?= "$1.00"
,
show (hours 1) ~?= "1h" -- currently h1.00
,
parseAmount "$1" ~?= dollars 1 -- currently 0
]
instance Show Amount where show = showAmountRoundedOrZero
nullamt = dollars 0
parseAmount :: String -> Amount
parseAmount s = nullamt
showAmountRoundedOrZero :: Amount -> String
showAmountRoundedOrZero (Amount cur qty) =
let rounded = punctuatethousands $ printf "%.2f" qty in
case rounded of
"0.00" -> "0"
"-0.00" -> "0"
otherwise -> (symbol cur) ++ rounded
punctuatethousands :: String -> String
punctuatethousands s =
sign ++ (punctuate int) ++ frac
where
(sign,num) = break isDigit s
(int,frac) = break (=='.') num
punctuate = reverse . concat . intersperse "," . triples . reverse
triples "" = []
triples s = [take 3 s] ++ (triples $ drop 3 s)
instance Num Amount where
abs (Amount c q) = Amount c (abs q)
signum (Amount c q) = Amount c (signum q)
fromInteger i = Amount (getcurrency "$") (fromInteger i)
(+) = amountAdd
(-) = amountSub
(*) = amountMul
Amount ac aq `amountAdd` b = Amount ac (aq + (quantity $ toCurrency ac b))
Amount ac aq `amountSub` b = Amount ac (aq - (quantity $ toCurrency ac b))
Amount ac aq `amountMul` b = Amount ac (aq * (quantity $ toCurrency ac b))
toCurrency :: Currency -> Amount -> Amount
toCurrency newc (Amount oldc q) =
Amount newc (q * (conversionRate oldc newc))