src/Pure/General/properties.ML

added "tasks_proof" statistics, via slighly odd global reference Future.forked_proofs (NB: Future.report_status is intertwined with scheduler thread);

(*  Title:      Pure/General/properties.ML
    Author:     Makarius

Property lists.
*)

signature PROPERTIES =
sig
  type entry = string * string
  type T = entry list
  val defined: T -> string -> bool
  val get: T -> string -> string option
  val put: entry -> T -> T
  val remove: string -> T -> T
end;

structure Properties: PROPERTIES =
struct

type entry = string * string;
type T = entry list;

fun defined (props: T) name = AList.defined (op =) props name;
fun get (props: T) name = AList.lookup (op =) props name;
fun put entry (props: T) = AList.update (op =) entry props;
fun remove name (props: T) = AList.delete (op =) name props;

end;