84 lines
2.0 KiB
Haskell
84 lines
2.0 KiB
Haskell
|
|
module BasicTypes
|
|
where
|
|
import Utils
|
|
|
|
|
|
type Date = String
|
|
|
|
-- generic tree. each node is a tuple of the node type and a
|
|
-- list of subtrees
|
|
newtype Tree a = Tree { node :: (a, [Tree a]) } deriving (Show,Eq)
|
|
branches = snd . node
|
|
|
|
-- amounts
|
|
{- a simple amount is a currency, quantity pair:
|
|
0
|
|
$1
|
|
£-50
|
|
EUR 3.44
|
|
HRS 1.5
|
|
DAYS 3
|
|
GOOG 500
|
|
|
|
a mixed amount is one or more simple amounts:
|
|
$50, EUR 3, APPL 500
|
|
HRS 16, $13.55, oranges 6
|
|
|
|
arithmetic:
|
|
$1 - $5 = $-4
|
|
$1 + EUR 0.76 = $2
|
|
EUR0.76 + $1 = EUR 1.52
|
|
EUR0.76 - $1 = 0
|
|
($5, HRS 2) + $1 = ($6, HRS 2)
|
|
($50, EUR 3, APPL 500) + ($13.55, oranges 6) = $67.51, APPL 500, oranges 6
|
|
($50, EUR 3) * $-1 = $-53.96
|
|
($50, APPL 500) * $-1 = error
|
|
|
|
-}
|
|
|
|
type Currency = String
|
|
|
|
data Amount = Amount {
|
|
currency :: Currency,
|
|
quantity :: Double
|
|
} deriving (Eq,Ord)
|
|
|
|
instance Show Amount where show = showAmountRoundedOrZero
|
|
|
|
showAmountRoundedOrZero :: Amount -> String
|
|
showAmountRoundedOrZero (Amount cur qty) =
|
|
let rounded = printf "%.2f" qty in
|
|
case rounded of
|
|
"0.00" -> "0"
|
|
"-0.00" -> "0"
|
|
otherwise -> cur ++ rounded
|
|
|
|
instance Num Amount where
|
|
abs (Amount c q) = Amount c (abs q)
|
|
signum (Amount c q) = Amount c (signum q)
|
|
fromInteger i = Amount "$" (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))
|
|
|
|
conversionRate :: Currency -> Currency -> Double
|
|
conversionRate oldc newc = (rate newc) / (rate oldc)
|
|
|
|
rate :: Currency -> Double
|
|
rate "$" = 1.0
|
|
rate "EUR" = 0.760383
|
|
rate "£" = 0.512527
|
|
rate _ = 1
|
|
|
|
|
|
data MixedAmount = MixedAmount [Amount] deriving (Eq,Ord)
|
|
|