Stop overriding ISO digits with CLDR digits.

For ~14 currencies ISO specifies 2 or 3 digits, but CLDR specifies 0,
because that better reflects real world usage, where the currency's
minor units no longer have value and aren't used in cash transactions.

However, it is common in such cases for the digits to still be used
for banking transactions, tax amounts, etc.
Since those represent common use cases for this package, it is safer to
default to the ISO digits, and let consumers further
restrict and round as needed.

Fixes #37.

gen.go

@@ -183,11 +183,6 @@ func main() {
 	}
 
 	log.Println("Processing...")
-	err = replaceDigits(currencies, assetDir)
-	if err != nil {
-		os.RemoveAll(assetDir)
-		log.Fatal(err)
-	}
 	locales, err := collectLocales(assetDir)
 	if err != nil {
 		os.RemoveAll(assetDir)
@@ -331,8 +326,6 @@ func fetchISO() (map[string]*currencyInfo, error) {
 			continue
 		}
 
-		// We use ISO digits here with a fallback to 2, but prefer CLDR
-		// data when available. See replaceDigits() for the next step.
 		digits := parseDigits(entry.Digits, 2)
 		currencies[entry.Code] = &currencyInfo{entry.Number, digits}
 	}
@@ -381,39 +374,6 @@ func collectLocales(dir string) ([]string, error) {
 	return locales, nil
 }
 
-// replaceDigits replaces currency digits with data from CLDR.
-//
-// CLDR data reflects real life usage more closely, specifying 0 digits
-// (instead of 2 in ISO data) for ~14 currencies, such as ALL and RSD.
-//
-// Note that CLDR does not have data for every currency, in which ase
-// the original ISO digits are kept.
-func replaceDigits(currencies map[string]*currencyInfo, dir string) error {
-	data, err := os.ReadFile(dir + "/cldr-json/cldr-core/supplemental/currencyData.json")
-	if err != nil {
-		return fmt.Errorf("replaceDigits: %w", err)
-	}
-	aux := struct {
-		Supplemental struct {
-			CurrencyData struct {
-				Fractions map[string]map[string]string
-			}
-		}
-	}{}
-	if err := json.Unmarshal(data, &aux); err != nil {
-		return fmt.Errorf("replaceDigits: %w", err)
-	}
-
-	for currencyCode := range currencies {
-		fractions, ok := aux.Supplemental.CurrencyData.Fractions[currencyCode]
-		if ok {
-			currencies[currencyCode].digits = parseDigits(fractions["_digits"], 2)
-		}
-	}
-
-	return nil
-}
-
 // generateCountryCurrencies generates the map of country codes to currency codes.
 func generateCountryCurrencies(dir string) (map[string]string, error) {
 	data, err := os.ReadFile(dir + "/cldr-json/cldr-core/supplemental/currencyData.json")