(* pidenv.sig
 *
 * (C) 2001 Lucent Technologies, Bell Labs
 *
 * Environments that bind persistent IDs.
 * (Instantiated to dynamic and symbolic environments by the compiler.)
 *)
(*local
    type pid = PersStamps.persstamp
in*)
signature PIDENV = sig

    type binding
    type env

    val empty : env
    val look: env -> PersStamps.persstamp -> binding option
    val bind: PersStamps.persstamp * binding * env -> env
    val atop: env * env -> env
    val remove: PersStamps.persstamp list * env -> env
    val consolidate: env -> env
    val singleton: PersStamps.persstamp * binding -> env
    val listItemsi: env -> (PersStamps.persstamp * binding) list
    val fromListi: (PersStamps.persstamp * binding) list -> env

    val mk : PersStamps.persstamp option * binding option -> env
end (* signature SYMENV *)
(*end*) (* local *)