(* 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
val seconds: T -> string -> Time.time
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;
fun seconds props name =
(case AList.lookup (op =) props name of
NONE => Time.zeroTime
| SOME s => Time.fromReal (the_default 0.0 (Real.fromString s)));
end;