Curious what your issue was with duck-typing. Were you effectively looking to create ADTs that are required to go through a specific step-by-step process, not s

Curious what your issue was with duck-typing. Were you effectively looking to create ADTs that are required to go through a specific step-by-step process, not simply 'look like' the thing that was expected? If so, you might be interested in [newtype-ts]. [newtype-ts]: https://github.com/gcanti/newtype-ts https://github.com/gcanti/newtype-ts