minted_finance

IBANs, BICs, ISINs and payment card numbers as well-modelled value types.

Part of the minted family: pure-Dart value types built on parse, don't validate, so the parser is the only door in and anything that came through it is well-formed by construction. Once you hold an Iban, it is a checksum-valid IBAN.

Install

dart pub add minted_finance

minted comes with it, holding the vocabulary a parse hands back (ParseOutcome, MintedFailure), and so does minted_constraints for the primitives this package's getters return. Nothing here drags in another domain's engine.

What's in the box

The check digits actually run: Iban computes mod-97 rather than matching a country's shape, and PaymentCardNumber is a class rather than an extension type precisely so printing one can't leak a PAN.

A quick taste

final iban = Iban.tryParse('gb29 nwbk 6016 1331 9268 19')!;
iban.value;        // 'GB29NWBK60161331926819'   (compact)
iban.countryCode;  // 'GB'
iban.checkDigits;  // (first: Digit, second: Digit)
iban.formatted;    // 'GB29 NWBK 6016 1331 9268 19'   (grouped paper form)

// Bic: the 8- and 11-character spellings of one office are the same value, XXX being the office:
final bic = Bic.tryParse('deut de ff')!;
bic.value;                        // 'DEUTDEFFXXX'
bic.bic8;                         // 'DEUTDEFF'   (the short form, rebuilt)
bic == Bic.tryParse('DEUTDEFFXXX');  // true
Bic.tryParse('DEUTZZFF');         // null: ZZ is not a country

// PaymentCardNumber masks itself, so a stray log line can't leak the number:
final card = PaymentCardNumber.tryParse('4111 1111 1111 1111')!;
'$card';          // 'PaymentCardNumber(••••1111)'
card.value;       // '4111111111111111'   (the only member that hands the number back)
card.cardScheme;  // CardScheme.visa   (read off the prefix, never validated)

// the scheme also reads from partial input, so a form can show the brand while you type:
PaymentCardNumber.cardSchemesOf('4');             // {CardScheme.visa}
PaymentCardNumber.tryParse('4111111111111112');   // null: fails the Luhn check

// Isin runs Luhn over the number with each letter expanded to two digits:
final isin = Isin.tryParse('au0000xvgza3')!;
isin.value;              // 'AU0000XVGZA3'
isin.nsin;               // '0000XVGZA'
Isin.tryParse('US0378331006');   // null: fails the Luhn check

The runnable version is the example.

One shape, every type

• Type.tryParse(input) hands back the value, or null when the input isn't valid
• Type.parse(input) hands back a ParseOutcome: the value, or a typed failure (IbanFailure, BicFailure, IsinFailure, PaymentCardNumberFailure) you can switch on, or read as a form-field message via .reasonOrNull. No door throws
• value equality, a canonical .value normalised on parse, and fromComponents for parts you already hold

The minted README is the family guide: the package index, handling failures, and the one caveat (never cast into a minted type).