discontinued Term.dest_abs / Logic.dest_all, which are officially superseded by Variable.dest_abs etc., but there are also Term.dest_abs_global to recover existing tools easily;
Simplifier and equational conversions demand a proper proof context;
(* Title: Pure/Sessions.thy
Author: Makarius
PIDE markup for session ROOT.
*)
theory Sessions
imports Pure
keywords "session" :: thy_decl
and "description" "directories" "options" "sessions" "theories"
"document_theories" "document_files" "export_files" :: quasi_command
and "global"
begin
ML \<open>
Outer_Syntax.command \<^command_keyword>\<open>session\<close> "PIDE markup for session ROOT"
Sessions.command_parser;
\<close>
end