Algrebraic data types

main.dart

// Définition d'une classe scellée pour représenter un résultat
// Sealed class : https://dart.dev/language/class-modifiers#sealed
sealed class ASealedClass {}
// cas 1
class Success extends ASealedClass {}
// cas 2
class Failure extends ASealedClass {}

/// sous la forme d'un enum
enum AnEnum { success, error }

/// sous la forme d'un record 
typedef ARecord = ({
  bool isSuccess,
});

/// demo time!
void main() {
  ASealedClass aClass = provide<ASealedClass>(() => Success());
  aClass = switch (aClass) {
    Success() => aClass,
    Failure() => aClass,
  };

  AnEnum anEnum = provide<AnEnum>(() => AnEnum.success);
  anEnum = switch (anEnum) {
    AnEnum.success => anEnum,
    AnEnum.error => anEnum,
  };

  ARecord aRecord = provide<ARecord>(() => (isSuccess: true));
  aRecord = switch (aRecord) {
    (isSuccess: true) => aRecord,
    (isSuccess: false) => aRecord,
  };
}

// method to alias type
T provide<T>(T Function() a) => a();