An Objective-C pattern for making sum types - Example.m

Example.m

#import "ExamplePrivate.h" // https://gist.github.com/hborders/12fcbe34cf4de68c2317bad92a8e223d

@implementation Example
- (instancetype _Nonnull)initPrivate {
  return [super init];
}
- (void)switchFoo:(void (^ _Nonnull)(ExampleFoo * _Nonnull foo_))fooBlock
              bar:(void (^ _Nonnull)(ExampleBar * _Nonnull bar_))barBlock {
  // Subclasses must implement and call
}
@end