44 lines
1.1 KiB
Haskell
44 lines
1.1 KiB
Haskell
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module BasicTypes
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where
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import Utils
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type Date = String
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type Status = Bool
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-- amounts
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-- amount arithmetic currently ignores currency conversion
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data Amount = Amount {
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currency :: String,
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quantity :: Double
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} deriving (Eq,Ord)
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instance Num Amount where
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abs (Amount c q) = Amount c (abs q)
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signum (Amount c q) = Amount c (signum q)
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fromInteger i = Amount "$" (fromInteger i)
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(+) = amountAdd
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(-) = amountSub
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(*) = amountMult
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Amount ca qa `amountAdd` Amount cb qb = Amount ca (qa + qb)
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Amount ca qa `amountSub` Amount cb qb = Amount ca (qa - qb)
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Amount ca qa `amountMult` Amount cb qb = Amount ca (qa * qb)
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instance Show Amount where show = amountRoundedOrZero
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amountRoundedOrZero :: Amount -> String
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amountRoundedOrZero (Amount cur qty) =
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let rounded = printf "%.2f" qty in
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case rounded of
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"0.00" -> "0"
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"-0.00" -> "0"
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otherwise -> cur ++ rounded
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-- generic tree. each node is a tuple of the node type and a
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-- list of subtrees
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newtype Tree a = Tree { node :: (a, [Tree a]) } deriving (Show,Eq)
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branches = snd . node
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