Safe Haskell | Safe-Inferred |
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- data Rates a b = Rates {}
- rebase :: (Ord a, Fractional b) => a -> Rates a b -> Rates a b
- exchangeRate :: (Ord a, Fractional b) => Rates a b -> a -> a -> Maybe b
Documentation
A map from currency to exchange rate against some reference currency
rebase :: (Ord a, Fractional b) => a -> Rates a b -> Rates a bSource
Change the reference currency to a different one found in the Map
:: (Ord a, Fractional b) | |
=> Rates a b | |
-> a | Source currency |
-> a | Target currency |
-> Maybe b |