40 lines
1.4 KiB
Haskell
40 lines
1.4 KiB
Haskell
{-|
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A 'Commodity' is a symbol representing a currency or some other kind of
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thing we are tracking, and some display preferences that tell how to
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display 'Amount's of the commodity - is the symbol on the left or right,
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are thousands separated by comma, significant decimal places and so on.
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-}
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module Ledger.Commodity
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where
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import Ledger.Utils
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import Ledger.Types
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-- convenient amount and commodity constructors, for tests etc.
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unknown = Commodity {symbol="", side=L,spaced=False,comma=False,precision=0}
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dollar = Commodity {symbol="$", side=L,spaced=False,comma=False,precision=2}
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euro = Commodity {symbol="EUR",side=L,spaced=False,comma=False,precision=2}
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pound = Commodity {symbol="£", side=L,spaced=False,comma=False,precision=2}
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hour = Commodity {symbol="h", side=R,spaced=False,comma=False,precision=1}
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dollars n = Amount dollar n Nothing
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euros n = Amount euro n Nothing
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pounds n = Amount pound n Nothing
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hours n = Amount hour n Nothing
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defaultcommodities = [dollar, euro, pound, hour, unknown]
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-- | Look up one of the hard-coded default commodities. For use in tests.
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comm :: String -> Commodity
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comm sym = fromMaybe
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(error "commodity lookup failed")
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$ find (\(Commodity{symbol=s}) -> s==sym) defaultcommodities
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-- | Find the conversion rate between two commodities. Currently returns 1.
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conversionRate :: Commodity -> Commodity -> Double
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conversionRate _ _ = 1
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