Sets of abstract types whose content cannot be inspected. An abstract type represents the whole sets of its values, and does not provide any way to represent subsets. These abstract types behave like atoms and are used to represent e.g. OCaml types such as float.
contains_sample s t checks whether the given sample represents an element of t.
Formatting functions :
val print : t->(Stdlib.Format.formatter -> unit) list
print t returns a list of functions that can print the combination of abstract types in t. Each abstract typename is prefixed by ! to differenciate it from a type identifier. If t is any, the set is simply printed as Abstract.