Declare data from the host application that is opaque (no syntax), like int but not like list or pair
type 'a declaration = {name : name;doc : doc;pp : Format.formatter -> 'a -> unit;eq : 'a -> 'a -> bool;hash : 'a -> int;hconsed : bool;constants : (name * 'a) list;}The eq function is used by unification. Limitation: unification of * two cdata cannot alter the constraint store. This can be lifted in the * future if there is user request. * * If the hconsed is true, then the readback function is * automatically hashcons the data using the eq and hash functions.
val declare : 'a declaration -> 'a Conversion.t