doc(library/init/env_ext): document environment extensions in use

library/init/env_ext.lean

@@ -0,0 +1,94 @@
+prelude
+
+/-
+Environment extensions:
+
+- inductive and quotient extensions will become part of the environment
+
+- private
+  * unsigned       m_counter
+  * name_map<name> m_inv_map;  // map: hidden-name -> user-name (for pretty printing purposes) it is serialized
+  * name_set       m_private_prefixes; // transient (it is used for register_private_name)
+
+- protected
+  * name_set m_protected;
+
+- noncomputable
+  * name_set
+
+- export_decl: it is used to implement the `export` command
+  * name_map<list<export_decl>> m_ns_map;   // mapping from namespace to "export declaration"
+
+- aux_recursors
+  * name_set m_aux_recursor_set;
+  * name_set m_no_confusion_set;
+
+- documentation
+  * list<doc_entry>       m_module_doc;      // this is not used
+  * name_map<std::string> m_doc_string_map;  // mapping declaration name to doc string
+
+- ginductive: it will be deleted
+
+- aliases: this is a transient object used during elaboration. We use it to store the mappings (user-facing-name -> private name); implementing `open` command; simulating `section` parameters; etc.
+  * bool             m_in_section;
+  * name_map<names>  m_aliases;
+  * name_map<name>   m_inv_aliases;
+  * name_map<name>   m_level_aliases;
+  * name_map<name>   m_inv_level_aliases;
+  * name_map<expr>   m_local_refs;
+
+- projection: it will be deleted
+
+- fingerprint: (we can store this information in the environment)
+  * uint64 m_fingerprint
+
+- eqn_lemmas: maps definition to its equational lemmas. It is used to implement tactics.
+  * name_map<list<simp_lemma>> m_lemmas;
+  * name_set                   m_has_simple_eqn_lemma;
+
+- user attributes:
+  * name_map<attribute_ptr> m_attrs;
+
+- Bytecode
+  * unsigned_map<vm_decl>           m_decls;
+  * unsigned_map<vm_cases_function> m_cases;
+  * name                            m_monitor;
+
+- module
+  *  std::vector<module_name> m_direct_imports;
+  *  list<std::shared_ptr<modification const>> m_modifications;
+  *  names        m_module_univs;
+  *  names        m_module_decls;
+  *  name_set     m_module_defs;
+  *  name_set     m_imported;
+  *  // Map from declaration name to olean file where it was defined
+  *  name_map<std::string>     m_decl2olean;
+  *  name_map<pos_info>        m_decl2pos_info;
+
+- scoped_ext: a general purpose scoped extension. It is used to implement
+  * parser/scanner tables
+  * inverse (it can be deleted after we remove g_inductive)
+  * attribute_manager (do we need them? we can try to keep user attributes only)
+    * elaboration strategy
+    * user commands
+    * use annonymous constructor when pretty printing
+    * "parsing-only"
+    * reducibility annotations
+    * [inline]
+    * [pattern]
+    * [inverse] (it can be deleted in the future)
+    * [class]
+    * [instance]
+    * [recursor]
+    * [simp]
+    * [congr]
+    * [refl]
+    * [symm]
+    * [trans]
+  * active_export_decls
+  * class
+  * user_recursors
+    * name_map<recursor_info> m_recursors;
+    * name_map<names>         m_type2recursors;
+  * relation_manager
+-/