feat(library/composition_manager): check if existing definition is definitionally equal

src/library/composition_manager.cpp

@@ -34,8 +34,7 @@ static environment update(environment const & env, composition_manager_ext const
     return env.update(g_ext->m_ext_id, std::make_shared<composition_manager_ext>(ext));
 }
 
-pair<environment, name> compose(type_checker & tc, name const & g, name const & f, optional<name> const & gf) {
-    environment const & env = tc.env();
+pair<environment, name> compose(environment const & env, type_checker & tc, name const & g, name const & f, optional<name> const & gf) {
     composition_manager_ext ext = get_extension(env);
     if (name const * it = ext.m_cache.find(mk_pair(g, f)))
         return mk_pair(env, *it);
@@ -70,7 +69,22 @@ pair<environment, name> compose(type_checker & tc, name const & g, name const &
     unsigned idx  = 1;
 
     // make sure name is unique
-    while (env.find(new_name)) {
+    while (true) {
+        auto it = env.find(new_name);
+        if (!it)
+            break;
+        if (it->is_definition() && it->get_num_univ_params() == f_decl.get_num_univ_params()) {
+            // check if definitions is definitionally equal to exisiting one
+            expr it_type = instantiate_type_univ_params(*it, f_ls);
+            expr it_val  = instantiate_value_univ_params(*it, f_ls);
+            if (tc.is_def_eq(it_type, new_type).first && tc.is_def_eq(it_val, new_val).first) {
+                // environment already contains a definition that is definitially equal to the new one.
+                // So, we do not need to create a new one
+                ext.m_cache.insert(mk_pair(g, f), new_name);
+                environment new_env = module::add(env, *g_key, [=](environment const &, serializer & s) { s << g << f << new_name; });
+                return mk_pair(update(new_env, ext), new_name);
+            }
+        }
         new_name = base_name.append_after(idx);
         idx++;
     }
@@ -84,7 +98,7 @@ pair<environment, name> compose(type_checker & tc, name const & g, name const &
 
 pair<environment, name> compose(environment const & env, name const & g, name const & f, optional<name> const & gf) {
     type_checker tc(env);
-    return compose(tc, g, f, gf);
+    return compose(env, tc, g, f, gf);
 }
 
 static void composition_reader(deserializer & d, shared_environment & senv,

src/library/composition_manager.h

@@ -13,7 +13,7 @@ namespace lean {
     If the environment already has a definition with this name, then adds the prefix _idx, where idx is a numeral.
     The result is a pair (new environment, new constant name).
 */
-pair<environment, name> compose(type_checker & tc, name const & g, name const & f, optional<name> const & gf = optional<name>());
+pair<environment, name> compose(environment const & env, type_checker & tc, name const & g, name const & f, optional<name> const & gf = optional<name>());
 pair<environment, name> compose(environment const & env, name const & g, name const & f, optional<name> const & gf = optional<name>());
 void initialize_composition_manager();
 void finalize_composition_manager();

src/library/init_module.cpp

@@ -40,6 +40,7 @@ Author: Leonardo de Moura
 #include "library/user_recursors.h"
 #include "library/class_instance_synth.h"
 #include "library/composition_manager.h"
+#include "library/tc_multigraph.h"
 
 namespace lean {
 void initialize_library_module() {
@@ -79,9 +80,11 @@ void initialize_library_module() {
     initialize_user_recursors();
     initialize_class_instance_elaborator();
     initialize_composition_manager();
+    initialize_tc_multigraph();
 }
 
 void finalize_library_module() {
+    finalize_tc_multigraph();
     finalize_composition_manager();
     finalize_class_instance_elaborator();
     finalize_user_recursors();

src/library/tc_multigraph.cpp

@@ -63,7 +63,7 @@ struct add_edge_fn {
 
     name compose(name const & src, name const & e1, name const & e2, name const & tgt) {
         name n = src + name("to") + tgt;
-        pair<environment, name> env_e = ::lean::compose(*m_tc, e2, e1, optional<name>(n));
+        pair<environment, name> env_e = ::lean::compose(m_env, *m_tc, e2, e1, optional<name>(n));
         m_env = env_e.first;
         return env_e.second;
     }
@@ -117,9 +117,15 @@ struct add_edge_fn {
 
 /** \brief Return true iff args contains Var(0), Var(1), ..., Var(args.size() - 1) */
 static bool check_var_args(buffer<expr> const & args) {
+    buffer<bool> found;
+    found.resize(args.size(), false);
     for (unsigned i = 0; i < args.size(); i++) {
-        if (!is_var(args[i]) || var_idx(args[i]) != i)
+        if (!is_var(args[i]))
             return false;
+        unsigned idx = var_idx(args[i]);
+        if (idx >= args.size() || found[idx])
+            return false;
+        found[idx] = true;
     }
     return true;
 }
@@ -149,16 +155,19 @@ pair<name, name> tc_multigraph::validate(environment const & env, name const & e
     declaration const & d = env.get(e);
     expr type = d.get_type();
     for (unsigned i = 0; i < num_args; i++) {
-        if (!is_pi(type))
+        if (!is_pi(type)) {
             throw_ex(m_kind, e);
+        }
         type = binding_body(type);
     }
-    if (!is_pi(type))
+    if (!is_pi(type)) {
         throw_ex(m_kind, e);
+    }
     buffer<expr> args;
     expr const & C = get_app_args(binding_domain(type), args);
-    if (!is_constant(C) || !check_levels(const_levels(C), d.get_univ_params()) || !check_var_args(args))
+    if (!is_constant(C) || !check_levels(const_levels(C), d.get_univ_params()) || !check_var_args(args)) {
         throw_ex(m_kind, e);
+    }
     name src = const_name(C);
     type = binding_body(type);
     name tgt;
@@ -168,13 +177,15 @@ pair<name, name> tc_multigraph::validate(environment const & env, name const & e
         tgt = *g_fun_sink;
     } else {
         expr const & D = get_app_fn(type);
-        if (is_constant(D))
+        if (is_constant(D)) {
             tgt = const_name(D);
-        else
+        } else {
             throw_ex(m_kind, e);
+        }
     }
-    if (src == tgt)
+    if (src == tgt) {
         throw_ex(m_kind, e);
+    }
     return mk_pair(src, tgt);
 }