Handles currency amounts, provides currency information and formatting.
Powered by CLDR v37, in just ~30kb of data.
Backstory: https://bojanz.github.io/price-currency-handling-go/
- All currency codes, their numeric codes and fraction digits.
- Currency symbols and formats for all locales.
- Amount struct, with value semantics (Fowler's Money pattern)
- Formatter, for formatting amounts and parsing formatted amounts.
amount, _ := currency.NewAmount("275.98", "EUR")
total, _ := amount.Mul("4")
locale := currency.NewLocale("fr")
formatter := currency.NewFormatter(locale)
fmt.Println(formatter.Format(total)) // 1 103,92 €
// Convert the amount to Iranian rial and show it in Farsi.
total, _ = total.Convert("IRR", "45.538")
total = total.Round()
locale = currency.NewLocale("fa")
formatter = currency.NewFormatter(locale)
fmt.Println(formatter.Format(total)) // ریال ۵۰٬۲۷۰- Real decimal implementation under the hood.
Currency amounts can't be floats. Storing integer minor units (2.99 => 299) becomes problematic once there are multiple currencies (difficult to sort in the DB), or there is a need for sub-minor-unit precision (due to merchant or tax requirements, etc). A real arbitrary-precision decimal type is required. Since Go doesn't have one natively, a userspace implementation is used, provided by the cockroachdb/apd package. The Amount struct provides an easy to use abstraction on top of it, allowing the underlying implementation to be replaced in the future without a backwards compatibility break.
- English as a priority.
Where possible, the en and en-US locales are given preferred treatment.
For example, looking up currency symbols is the quickest for these locales,
since they are the most commonly used.
- Automatically generated CLDR data.
Updating to the latest CLDR release is always one go generate away.
- Smart filtering of CLDR data.
CLDR contains 542 locales, not all of which are likely to be used. This list is reduced to 381 using a list of ignored locales, containing constructed languages (Esperanto, Volapuk), historical languages (Church Slavic, Prussian), secondary non-official languages (Cornish, Gujarati, Cherokee). The ignore list is maintained by community feedback, developers wishing to use an ignored locale can open a pull request.
Once gathered, locales are filtered to remove all data not used by this package,
and then deduplicated by parent (e.g. don't keep fr-CH if fr has the
same data).
Currency symbols are grouped together to avoid repetition. For example:
"ARS": {
{"ARS", []string{"en", "fr-CA"}},
{"$", []string{"es-AR"}},
{"$AR", []string{"fr"}},
}
Currency names are not included because they are rarely shown, but need significant space. Instead, they can be fetched on the frontend via Intl.DisplayNames.