Wallet
Subject
Given a Wallet containing Stocks, build a function that compute the value of wallet in a currency.
The Stocks have a quantity and a StockType. The StockType can be for example petroleum, Euros, bitcoins and Dollars.
To value the portfilio in a Currency you can use external api to provide rate exchanges (some are provided below).
Object sample
Value value = Wallet(Stock(5, PETROLEUM)).value(EUR, rateProvider)
With rateProvider an implementation of this interface :
rateProvider.rate(from: StockType, to: Currency) -> double
and PETROLEUM is a StockType and EUR is a Currency.
Functional sample
Value value = compute_value(Wallet(Stock(5, PETROLEUM), EUR, rateProvider))
Where rateProvider is a function with this signature :
rateProvider(from: StockType, to: Currency) -> double
and PETROLEUM is a StockType and EUR is a Currency.
Suggested rates sources
Some APIs can be used to provides rates: