package orsetto

Use opt n v to extract v' if n is equivalent to the encapsulated runtime type, otherwise raises an exception (conventionally Type_error).

Use opt n v to extract Some v' if n is equivalent to the encapsulated runtime type, otherwise returns None.

Use eq a b to produce the equivalence constraint for the types associated with nyms a and b under the horizon. Returns Eq if a and b are nyms for equivalent types, otherwise raises Type_error.

Use ck n v to test whether n is equivalent to the encapsulated runtime type.