1234567891011121314151617181920212223242526272829303132333435363738394041(** Universal maps *)moduletypeS=sig(** A universal map is a map that can store values for arbitrary keys. It is
the the key that conveys the type of the data associated to it. *)typetmoduleKey:sigtype'atvalcreate:name:string->('a->Dyn.t)->'atendvalempty:tvalis_empty:t->boolvalmem:t->'aKey.t->boolvalset:t->'aKey.t->'a->tvaladd:t->'aKey.t->'a->(t,'a)Result.tvalupdate:t->'aKey.t->f:('aoption->'aoption)->tvalremove:t->'aKey.t->tvalfind:t->'aKey.t->'aoptionvalfind_exn:t->'aKey.t->'avalsingleton:'aKey.t->'a->t(** [superpose a b] is [b] augmented with bindings of [a] that are not in [b]. *)valsuperpose:t->t->tvalto_dyn:t->Dyn.t(** [to_dyns m] is an assoc list pairing keys to (representations of) values *)valto_dyns:t->(string*Dyn.t)listend