hledger/Currency.hs
2007-07-04 02:24:33 +00:00

32 lines
827 B
Haskell

module Currency
where
import qualified Data.Map as Map
import Data.Map ((!))
import Utils
import Types
currencies =
[
Currency "$" 1
,Currency "EUR" 0.760383
,Currency "£" 0.512527
,Currency "h" 60 -- hours
,Currency "m" 1 -- minutes
]
currencymap = Map.fromList [(sym, c) | c@(Currency sym rate) <- currencies]
getcurrency :: String -> Currency
getcurrency s = Map.findWithDefault (Currency s 1) s currencymap
conversionRate :: Currency -> Currency -> Double
conversionRate oldc newc = (rate newc) / (rate oldc)
-- convenient amount constructors
dollars n = Amount (getcurrency "$") n 2
euro n = Amount (getcurrency "EUR") n 2
pounds n = Amount (getcurrency "£") n 2
hours n = Amount (getcurrency "h") n 2
minutes n = Amount (getcurrency "m") n 2