chore(kernel/replace_fn): add syntax sugar for replace function

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>

src/frontends/lean/elaborator.cpp

@@ -101,7 +101,7 @@ public:
         if (!has_univ_metavar(e)) {
             return e;
         } else {
-            return replace(e, [&](expr const & e, unsigned) {
+            return replace(e, [&](expr const & e) {
                     if (!has_univ_metavar(e)) {
                         return some_expr(e);
                     } else if (is_sort(e)) {

src/frontends/lean/inductive_cmd.cpp

@@ -341,7 +341,7 @@ struct inductive_cmd_fn {
         section parameters \c section_params as arguments.
     */
     expr fix_inductive_occs(expr const & type, buffer<inductive_decl> const & decls, buffer<expr> const & section_params) {
-        return replace(type, [&](expr const & e, unsigned) {
+        return replace(type, [&](expr const & e) {
                 if (!is_constant(e))
                     return none_expr();
                 if (!std::any_of(decls.begin(), decls.end(),
@@ -455,7 +455,7 @@ struct inductive_cmd_fn {
         for (auto & d : decls) {
             buffer<intro_rule> new_irs;
             for (auto & ir : inductive_decl_intros(d)) {
-                expr new_type = replace(intro_rule_type(ir), [&](expr const & e, unsigned) {
+                expr new_type = replace(intro_rule_type(ir), [&](expr const & e) {
                         if (!is_constant(e))
                             return none_expr();
                         if (!std::any_of(decls.begin(), decls.end(),

src/frontends/lean/parser.cpp

@@ -243,7 +243,7 @@ expr parser::propagate_levels(expr const & e, levels const & ls) {
     if (is_nil(ls)) {
         return e;
     } else {
-        return replace(e, [&](expr const & e, unsigned) {
+        return replace(e, [&](expr const & e) {
                 if (is_constant(e)) {
                     auto it = m_env.find(const_name(e));
                     if (it) {

src/kernel/instantiate.cpp

@@ -156,7 +156,7 @@ expr beta_reduce(expr t) {
 expr instantiate_univ_params(expr const & e, level_param_names const & ps, levels const & ls) {
     if (!has_param_univ(e))
         return e;
-    return replace(e, [&](expr const & e, unsigned) -> optional<expr> {
+    return replace(e, [&](expr const & e) -> optional<expr> {
             if (!has_param_univ(e))
                 return some_expr(e);
             if (is_constant(e)) {

src/kernel/replace_fn.h

@@ -21,4 +21,7 @@ namespace lean {
    if f return none_expr.
 */
 expr replace(expr const & e, std::function<optional<expr>(expr const &, unsigned)> const & f);
+inline expr replace(expr const & e, std::function<optional<expr>(expr const &)> const & f) {
+    return replace(e, [&](expr const & e, unsigned) { return f(e); });
+}
 }

src/library/deep_copy.cpp

@@ -27,7 +27,7 @@ expr copy(expr const & a) {
 
 expr deep_copy(expr const & e) {
     scoped_expr_caching scope(false);
-    return replace(e, [](expr const & e, unsigned) {
+    return replace(e, [](expr const & e) {
             if (is_atomic(e))
                 return some_expr(copy(e));
             else

src/library/level_names.cpp

@@ -78,7 +78,7 @@ static levels rename_param_levels(levels const & ls, name_map<name> const & para
 
 // Rename universe parameters occurring in e using the given mapping
 static expr rename_param_levels(expr const & e, name_map<name> const & param_name_map) {
-    return replace(e, [&](expr const & e, unsigned) {
+    return replace(e, [&](expr const & e) {
             if (is_constant(e))
                 return some_expr(update_constant(e, rename_param_levels(const_levels(e), param_name_map)));
             else if (is_sort(e))

src/library/tactic/apply_tactic.cpp

@@ -165,7 +165,7 @@ level refresh_univ_metavars(level const & l, name_generator & ngen, name_map<lev
 expr refresh_univ_metavars(expr const & e, name_generator & ngen) {
     if (has_univ_metavar(e)) {
         name_map<level> level_map;
-        return replace(e, [&](expr const & e, unsigned) {
+        return replace(e, [&](expr const & e) {
                 if (!has_univ_metavar(e))
                     return some_expr(e);
                 if (is_sort(e))