💰unison-money

A Small library for working with Money in Unison

Install

This library is currently very much in the development and exploration phase.

Install latest (pre-release):

.> pull https://github.com/hojberg/unison-money:.releases._latest external.money

The design of the library is built after a couple of principles.

We want to ensure Money is handled correctly and that money math is sound. The amount is stored as an Int in "cents" (as a term meaning to any minor part of a currency).
It should not be possible to do any math operations of Money of different currencies. This is done by a type variable in the constructor. Currently any type can be added as a currency, though the library does come with a set of currencies. Typeclasses might help tighting up this API in the future.
Regular division of Money is tough and doesn't quite make sense because you can't have half a penny. Instead we allow splitting Money where whole remainder is added to one of the chunks: 10 split into 3, results in 3 new Money types, 2 where the amount is 3 and 1 where the amount is 4. Note that there are cases where fractional pennies make sense, but that has not been the focus here.

Money Constructor: Create a Money value with Money USD +499 for an amount representing $ 4.99
Money.toText: Simply formats the Money as a Text (in the format of USD 4.99 with any regard for localized formatting (this will be added later): Money.toText : Money a -> Text
Money.+ (aliased as plus)
Money.- (aliased as minus)
Money.* (aliased as multiply)
Money.split: Take 1 Money and split into Nat chunks. Returns a list of the possible splits with whole remainders added to the Money values at the end of the list: Money.split 3 (Money USD +10) (10 cents) results in [Money USD +3, Money USD +3, Money USD +4]