module type String_datatype_with_collections =sig..end
Signature requires to build custom collection parameters in which elements are convertible to string.
include Datatype.S_with_collections
val of_string : string -> tCannot_build if there is no element corresponding to the given
string.val of_singleton_string : string -> Set.tIf a single string can be mapped to several elements. Can
default to no_element_of_string to indicate that each string s is
mapped exactly to of_string s.
val to_string : t -> string