I hear you although I’m no fintech guru. Its why in ex_money I never round implicitly, only ever explicitly.
I am pretty confident that the Decimal lib works correctly to arbitrary precision although of course when division is involved there can always be issues. Arguably support for Decimal and Rational numbers would be useful.
if you defined something like:
defprotocol Money.Access do
@doc Access money components
def currency(money)
def amount(money)
end
defimpl Money.Access, for: Any do
def currency(money), do: Map.get(money, :currency)
def amount(money), do: Map.get(money, :amount)
end
that would give a reasonable default for many libs and easy implementation for other lib writers. And then as a byproduct we could end of with a community endorsed protocol that could, if required, be extended.
I thought a few times that it would be handy to have a central registration of protocols that could be used to aid integrations like this but thats also hard to manage…
