(* ||M|| This file is part of HELM, an Hypertextual, Electronic ||A|| Library of Mathematics, developed at the Computer Science ||T|| Department, University of Bologna, Italy. ||I|| ||T|| HELM is free software; you can redistribute it and/or ||A|| modify it under the terms of the GNU General Public License \ / version 2 or (at your option) any later version. \ / This software is distributed as is, NO WARRANTY. V_______________________________________________________________ *) type id = string (* identifier *) type qid = id * bool * id list (* qualified identifier: name, local?, path *) type term = Sort of bool (* sorts: true = TYPE, false = PROP *) | GRef of qid * term list (* reference: name, arguments *) | Appl of term * term (* application: argument, function *) | Abst of id * term * term (* abstraction: name, domain, scope *) type entity = Section of (bool * id) option (* section: Some true = open, Some false = reopen, None = close last *) | Context of qid option (* context: Some = last node, None = root *) | Block of id * term (* block opener: name, domain *) | Decl of id * term (* declaration: name, domain *) | Def of id * term * bool * term (* definition: name, domain, transparent?, body *)