shadow-t.sml

(*
	Shadows - Abstract, lazy, functional sequences
	Copyright 2011 Christopher Cramer

	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program. If not, see http://www.gnu.org/licenses/.
*)

(*
	Shadow.t must be defined before SEQUENCE, but Shadow itself
	is constrained by SHADOW, which includes SEQUENCE. So we define
	Shadow.t (and Shadow.access, upon which it depends) alone here.
*)
structure Shadow = struct
	datatype access = Sequential | Random
	datatype 'a t = T of {
		access: access
		, getItem: unit -> ('a * 'a t) option
		, sub: int -> 'a
		, length: unit -> int
	}
end