diff --git a/src/frontends/lean/builtin_cmds.cpp b/src/frontends/lean/builtin_cmds.cpp
index 73edeca55..d44b601a9 100644
--- a/src/frontends/lean/builtin_cmds.cpp
+++ b/src/frontends/lean/builtin_cmds.cpp
@@ -109,7 +109,7 @@ environment check_cmd(parser & p) {
     formatter const & fmt = reg.get_formatter();
     options opts          = p.ios().get_options();
     unsigned indent       = get_pp_indent(opts);
-    format r = group(format{fmt(e), space(), colon(), nest(indent, compose(line(), fmt(type)))});
+    format r = group(fmt(e) + space() + colon() + nest(indent, line() + fmt(type)));
     reg << mk_pair(r, opts) << endl;
     return p.env();
 }
diff --git a/src/frontends/lean/elaborator.cpp b/src/frontends/lean/elaborator.cpp
index db0b7a00c..e4208867e 100644
--- a/src/frontends/lean/elaborator.cpp
+++ b/src/frontends/lean/elaborator.cpp
@@ -607,7 +607,7 @@ public:
                 expr new_m    = instantiate_meta(m, tmp);
                 expr new_type = type_checker(_env).infer(new_m).first;
                 proof_state ps(goals(goal(new_m, new_type)), substitution(), name_generator("dontcare"));
-                return format({format("failed to synthesize placeholder"), line(), ps.pp(fmt)});
+                return format("failed to synthesize placeholder") + line() + ps.pp(fmt);
             });
     }
 
diff --git a/src/frontends/lean/pp.cpp b/src/frontends/lean/pp.cpp
index 34dc4c4fc..99a036f77 100644
--- a/src/frontends/lean/pp.cpp
+++ b/src/frontends/lean/pp.cpp
@@ -172,7 +172,7 @@ auto pretty_fn::pp_sort(expr const & e) -> result {
     if (m_env.impredicative() && e == Prop) {
         return mk_result(format("Prop"));
     } else if (m_universes) {
-        return mk_result(group(format({format("Type.{"), nest(6, pp_level(sort_level(e))), format("}")})));
+        return mk_result(group(format("Type.{") + nest(6, pp_level(sort_level(e))) + format("}")));
     } else {
         return mk_result(format("Type"));
     }
@@ -295,7 +295,7 @@ auto pretty_fn::pp_pi(expr const & e) -> result {
     if (is_arrow(e)) {
         result lhs = pp_child(binding_domain(e), get_arrow_prec());
         result rhs = pp_child(lift_free_vars(binding_body(e), 1), get_arrow_prec()-1);
-        format r   = group(format{lhs.first, space(), m_unicode ? g_arrow_n_fmt : g_arrow_fmt, line(), rhs.first});
+        format r   = group(lhs.first + space() + (m_unicode ? g_arrow_n_fmt : g_arrow_fmt) + line() + rhs.first);
         return mk_result(r, get_arrow_prec()-1);
     } else {
         expr b = e;
@@ -346,12 +346,12 @@ auto pretty_fn::pp_let(expr e) -> result {
         name const & n = local_pp_name(d.first);
         format t       = pp_child(mlocal_type(d.first), 0).first;
         format v       = pp_child(d.second, 0).first;
-        r += nest(3 + 1, compose(beg, group(format{format(n), space(),
-                            colon(), nest(n.size() + 1 + 1 + 1, compose(space(), t)), space(), g_assign_fmt,
-                            nest(m_indent, format{line(), v, sep})})));
+        r += nest(3 + 1, compose(beg, group(format(n) + space() + colon()
+                                            + nest(n.size() + 1 + 1 + 1, space() + t) + space() + g_assign_fmt
+                                            + nest(m_indent, line() + v + sep))));
     }
     format b = pp_child(e, 0).first;
-    r += format{line(), g_in_fmt, space(), nest(2 + 1, b)};
+    r += line() + g_in_fmt + space() + nest(2 + 1, b);
     return mk_result(r, 0);
 }
 
@@ -365,14 +365,14 @@ auto pretty_fn::pp_have(expr const & e) -> result {
     format type_fmt  = pp_child(mlocal_type(local), 0).first;
     format proof_fmt = pp_child(proof, 0).first;
     format body_fmt  = pp_child(body, 0).first;
-    format r = format{g_have_fmt, space(), format(n), space()};
+    format r = g_have_fmt + space() + format(n) + space();
     if (binding_info(binding).is_contextual())
         r += compose(g_fact_fmt, space());
-    r += format{colon(), nest(m_indent, format{line(), type_fmt, comma(), space(), g_from_fmt})};
+    r += colon() + nest(m_indent, line() + type_fmt + comma() + space() + g_from_fmt);
     r = group(r);
-    r += nest(m_indent, compose(line(), compose(proof_fmt, comma())));
+    r += nest(m_indent, line() + proof_fmt + comma());
     r = group(r);
-    r += compose(line(), body_fmt);
+    r += line() + body_fmt;
     return mk_result(r, 0);
 }
 
@@ -381,7 +381,7 @@ auto pretty_fn::pp_show(expr const & e) -> result {
     expr binding     = get_annotation_arg(app_fn(e));
     format type_fmt  = pp_child(binding_domain(binding), 0).first;
     format proof_fmt = pp_child(proof, 0).first;
-    format r = format{g_show_fmt, space(), nest(5, type_fmt), comma(), space(), g_from_fmt};
+    format r = g_show_fmt + space() + nest(5, type_fmt) + comma() + space() + g_from_fmt;
     r = group(r);
     r += nest(m_indent, compose(line(), proof_fmt));
     return mk_result(group(r), 0);
diff --git a/src/kernel/level.cpp b/src/kernel/level.cpp
index cda304343..7c12fdb03 100644
--- a/src/kernel/level.cpp
+++ b/src/kernel/level.cpp
@@ -521,7 +521,7 @@ format pp(level l, bool unicode, unsigned indent) {
         case level_kind::Param: case level_kind::Global:
             return format(to_param_core(l).m_id);
         case level_kind::Meta:
-            return format{format("?"), format(meta_id(l))};
+            return format("?") + format(meta_id(l));
         case level_kind::Succ:
             return group(compose(format("succ"), nest(indent, compose(line(), pp_child(succ_of(l), unicode, indent)))));
         case level_kind::Max: case level_kind::IMax: {
@@ -545,7 +545,7 @@ format pp(level const & l, options const & opts) {
 
 format pp(level const & lhs, level const & rhs, bool unicode, unsigned indent) {
     format leq = unicode ? format("≤") : format("<=");
-    return group(format{pp(lhs, unicode, indent), space(), leq, line(), pp(rhs, unicode, indent)});
+    return group(pp(lhs, unicode, indent) + space() + leq + line() + pp(rhs, unicode, indent));
 }
 
 format pp(level const & lhs, level const & rhs, options const & opts) {
diff --git a/src/kernel/pos_info_provider.cpp b/src/kernel/pos_info_provider.cpp
index 03be0886f..37cc22fac 100644
--- a/src/kernel/pos_info_provider.cpp
+++ b/src/kernel/pos_info_provider.cpp
@@ -13,7 +13,7 @@ char const * pos_info_provider::get_file_name() const {
 format pos_info_provider::pp(expr const & e) const {
     try {
         auto p = get_pos_info_or_some(e);
-        return format{format(get_file_name()), colon(), format(p.first), colon(), format(p.second), colon()};
+        return format(get_file_name()) + colon() + format(p.first) + colon() + format(p.second) + colon();
     } catch (exception &) {
         return format();
     }
diff --git a/src/library/simplifier/rewrite_rule_set.cpp b/src/library/simplifier/rewrite_rule_set.cpp
index 1a476b0fb..84b2265da 100644
--- a/src/library/simplifier/rewrite_rule_set.cpp
+++ b/src/library/simplifier/rewrite_rule_set.cpp
@@ -116,7 +116,7 @@ format rewrite_rule_set::pp(formatter const & fmt, options const & opts) const {
                 r += format(" [disabled]");
             if (rule.must_check_types())
                 r += format(" [check]");
-            r += format{space(), colon(), space()};
+            r += space() + colon() + space();
             r += nest(indent, fmt(rule.get_ceq(), opts));
         });
     return r;
diff --git a/src/library/tactic/goal.cpp b/src/library/tactic/goal.cpp
index 46df614d8..a50dbe67b 100644
--- a/src/library/tactic/goal.cpp
+++ b/src/library/tactic/goal.cpp
@@ -29,10 +29,10 @@ format goal::pp(formatter const & fmt) const {
     for (auto it = tmp.begin(); it != end; ++it) {
         if (first) first = false; else r += compose(comma(), line());
         expr l     = *it;
-        r += format{fmt(l), space(), colon(), nest(indent, compose(line(), fmt(mlocal_type(l))))};
+        r += fmt(l) + space() + colon() + nest(indent, line() + fmt(mlocal_type(l)));
     }
     r = group(r);
-    r += format{line(), turnstile, space(), nest(indent, fmt(conclusion))};
+    r += line() + turnstile + space() + nest(indent, fmt(conclusion));
     return group(r);
 }
 
diff --git a/src/library/tactic/proof_state.cpp b/src/library/tactic/proof_state.cpp
index 93ce5e6d8..08435238d 100644
--- a/src/library/tactic/proof_state.cpp
+++ b/src/library/tactic/proof_state.cpp
@@ -36,7 +36,7 @@ format proof_state::pp(formatter const & fmt) const {
     for (auto const & g : get_goals()) {
         if (first) first = false; else r += line();
         if (show_goal_names) {
-            r += group(format{format(g.get_name()), colon(), nest(indent, compose(line(), g.pp(fmt)))});
+            r += group(format(g.get_name()) + colon() + nest(indent, line() + g.pp(fmt)));
         } else {
             r += g.pp(fmt);
         }
diff --git a/src/library/unifier.cpp b/src/library/unifier.cpp
index 60c5a0d77..ac73c5d78 100644
--- a/src/library/unifier.cpp
+++ b/src/library/unifier.cpp
@@ -628,7 +628,7 @@ struct unifier_fn {
                 r += pp_indent_expr(fmt, rhs);
                 buffer<expr> locals;
                 auto m = get_app_args(lhs, locals);
-                r += format({line(), format("containing '"), fmt(bad_local), format("', to placeholder '"), fmt(m), format("'")});
+                r += line() + format("containing '") + fmt(bad_local) + format("', to placeholder '") + fmt(m) + format("'");
                 if (locals.empty()) {
                     r += format(", in the empty local context");
                 } else {
diff --git a/src/tests/util/format.cpp b/src/tests/util/format.cpp
index d098da3b7..b57581d19 100644
--- a/src/tests/util/format.cpp
+++ b/src/tests/util/format.cpp
@@ -30,16 +30,13 @@ static void tst1() {
     format f4 = nest(3, f3);
     format f5 = line();
     format f6(f4, f5);
-    format f7 = nest(10, format{f6, f4, f6, f4});
+    format f7 = nest(10, f6 + f4 + f6 + f4);
     format f8(f_atom1, nest(3, format(line(), f_atom1)));
     format f9 = f7 + f8;
     format f10;
     f10 += f6 + f5 + f3;
     format f11 = above(f1, above(above(f2, f3), f4));
-    format f12 = paren(format{format("a"),
-                              format("b"),
-                              format("c"),
-                              format("d")});
+    format f12 = paren(format("a") + format("b") + format("c") + format("d"));
 
     std::vector<pair<std::string, format>> v =
         {{"f1",  f1},
diff --git a/src/util/sexpr/format.cpp b/src/util/sexpr/format.cpp
index 605734307..52a3967bf 100644
--- a/src/util/sexpr/format.cpp
+++ b/src/util/sexpr/format.cpp
@@ -167,21 +167,19 @@ format group(format const & f) {
     }
 }
 format above(format const & f1, format const & f2) {
-    return format{f1, line(), f2};
+    return f1 + line() + f2;
 }
 format bracket(std::string const & l, format const & x, std::string const & r) {
-    return group(nest(l.size(), format{format(l), x, format(r)}));
+    return group(nest(l.size(), format(l) + x + format(r)));
 }
 format paren(format const & x) {
-    return group(nest(1, format{lp(), x, rp()}));
+    return group(nest(1, lp() + x + rp()));
 }
 
 // wrap = <+/>
 // wrap x y = x <> (text " " :<|> line) <> y
 format wrap(format const & f1, format const & f2) {
-    return format{f1,
-                  choice(format(" "), line()),
-                  f2};
+    return f1 + choice(format(" "), line()) + f2;
 }
 
 /**
@@ -391,7 +389,7 @@ struct sexpr_pp_fn {
                 if (is_nil(*curr)) {
                     return paren(r);
                 } else if (!is_cons(*curr)) {
-                    return group(nest(1, format{lp(), r, space(), dot(), line(), apply(*curr), rp()}));
+                    return group(nest(1, lp() + r + space() + dot() + line() + apply(*curr) + rp()));
                 } else {
                     r += line();
                 }
diff --git a/src/util/sexpr/options.cpp b/src/util/sexpr/options.cpp
index a359c4983..f537b8d27 100644
--- a/src/util/sexpr/options.cpp
+++ b/src/util/sexpr/options.cpp
@@ -174,11 +174,11 @@ format pp(options const & o) {
             name const & n = to_name(head(p));
             unsigned sz = n.size();
             unsigned indent = unicode ? sz+3 : sz+4;
-            r += group(nest(indent, format{pp(head(p)), space(), format(arrow), space(), pp(tail(p))}));
+            r += group(nest(indent, pp(head(p)) + space() + format(arrow) + space() + pp(tail(p))));
         });
     format open  = unicode ? format(g_left_angle_bracket) : lp();
     format close = unicode ? format(g_right_angle_bracket) : rp();
-    return group(nest(1, format{open, r, close}));
+    return group(nest(1, open + r + close));
 }
 
 std::ostream & operator<<(std::ostream & out, options const & o) {