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51 lines
1.9 KiB
Elixir
51 lines
1.9 KiB
Elixir
# The Pragmatic Bookshelf has offices in Texas (TX) and North Carolina (NC), so we have to charge sales tax on orders shipped to these states.
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# The rates can be expressed as a keyword list (I wish it were that simple.…):
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# tax_rates = [ NC: 0.075, TX: 0.08 ]
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# Here’s a list of orders:
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# orders = [
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# [ id: 123, ship_to: :NC, net_amount: 100.00 ],
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# [ id: 124, ship_to: :OK, net_amount: 35.50 ],
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# [ id: 125, ship_to: :TX, net_amount: 24.00 ],
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# [ id: 126, ship_to: :TX, net_amount: 44.80 ],
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# [ id: 127, ship_to: :NC, net_amount: 25.00 ],
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# [ id: 128, ship_to: :MA, net_amount: 10.00 ],
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# [ id: 129, ship_to: :CA, net_amount: 102.00 ],
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# [ id: 130, ship_to: :NC, net_amount: 50.00 ] ]
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# Write a function that takes both lists and returns a copy of the orders, but with an extra field, total_amount, which is the net plus sales tax.
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# If a shipment is not to NC or TX, there’s no tax applied.
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tax_rates = [ NC: 0.075, TX: 0.08 ]
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orders= [
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[ id: 123, ship_to: :NC, net_amount: 100.00 ],
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[ id: 124, ship_to: :OK, net_amount: 35.50 ],
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[ id: 125, ship_to: :TX, net_amount: 24.00 ],
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[ id: 126, ship_to: :TX, net_amount: 44.80 ],
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[ id: 127, ship_to: :NC, net_amount: 25.00 ],
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[ id: 128, ship_to: :MA, net_amount: 10.00 ],
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[ id: 129, ship_to: :CA, net_amount: 102.00 ],
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[ id: 130, ship_to: :NC, net_amount: 50.00 ]
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]
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defmodule Calculator do
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def process(orders, tax_rates) do
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for order <- orders, do: order ++ [ total_amount: total_amount(order, tax_rates) ]
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end
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defp total_amount(order, tax_rates) do
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tax_rate = tax_rates[order[:ship_to]]
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if tax_rate == nil do
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order[:net_amount]
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else
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order[:net_amount] + order[:net_amount] * tax_rate
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end
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end
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end
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IO.inspect Calculator.process(orders, tax_rates)
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