fix(frontends/lean/pp): print notation produces incorrect output

fixes #604

src/frontends/lean/builtin_cmds.cpp

@@ -133,6 +133,7 @@ static bool print_parse_table(parser & p, parse_table const & t, bool nud, buffe
     options os   = ios.get_options();
     os = os.update_if_undef(get_pp_full_names_option_name(), true);
     os = os.update(get_pp_notation_option_name(), false);
+    os = os.update(get_pp_preterm_name(), true);
     ios.set_options(os);
     optional<token_table> tt(get_token_table(p.env()));
     t.for_each([&](unsigned num, notation::transition const * ts, list<expr> const & overloads) {

src/frontends/lean/pp.cpp

@@ -286,6 +286,7 @@ void pretty_fn::set_options_core(options const & o) {
     m_numerals        = get_pp_numerals(o);
     m_abbreviations   = get_pp_abbreviations(o);
     m_extra_spaces    = get_pp_extra_spaces(o);
+    m_preterm         = get_pp_preterm(o);
     m_hide_full_terms = get_formatter_hide_full_terms(o);
     m_num_nat_coe     = m_numerals && !m_coercion && has_coercion_num_nat(m_env);
 }
@@ -301,7 +302,11 @@ format pretty_fn::pp_level(level const & l) {
 }
 
 bool pretty_fn::is_implicit(expr const & f) {
-    if (m_implict)
+    // Remark: we assume preterms do not have implicit arguments,
+    // since they have not been elaborated yet.
+    // Moreover, the type checker will probably produce an error
+    // when trying to infer type information
+    if (m_implict || m_preterm)
         return false; // showing implicit arguments
     if (!closed(f)) {
         // the Lean type checker assumes expressions are closed.
@@ -505,8 +510,10 @@ auto pretty_fn::pp_local(expr const & e) -> result {
 }
 
 bool pretty_fn::has_implicit_args(expr const & f) {
-    if (!closed(f)) {
-        // the Lean type checker assumes expressions are closed.
+    if (!closed(f) || m_preterm) {
+        // The Lean type checker assumes expressions are closed.
+        // If preterms are being processed, then we assume
+        // there are no implicit arguments.
         return false;
     }
     name_generator ngen(*g_tmp_prefix);

src/frontends/lean/pp.h

@@ -69,6 +69,7 @@ private:
     bool                m_abbreviations;
     bool                m_hide_full_terms;
     bool                m_extra_spaces;
+    bool                m_preterm;
 
     name mk_metavar_name(name const & m);
     name mk_local_name(name const & n, name const & suggested);

src/library/pp_options.cpp

@@ -67,6 +67,10 @@ Author: Leonardo de Moura
 #define LEAN_DEFAULT_PP_EXTRA_SPACES false
 #endif
 
+#ifndef LEAN_DEFAULT_PP_PRETERM
+#define LEAN_DEFAULT_PP_PRETERM false
+#endif
+
 namespace lean {
 static name * g_pp_max_depth       = nullptr;
 static name * g_pp_max_steps       = nullptr;
@@ -83,6 +87,7 @@ static name * g_pp_beta            = nullptr;
 static name * g_pp_numerals        = nullptr;
 static name * g_pp_abbreviations   = nullptr;
 static name * g_pp_extra_spaces    = nullptr;
+static name * g_pp_preterm         = nullptr;
 static list<options> * g_distinguishing_pp_options = nullptr;
 
 void initialize_pp_options() {
@@ -101,6 +106,7 @@ void initialize_pp_options() {
     g_pp_numerals        = new name{"pp", "numerals"};
     g_pp_abbreviations   = new name{"pp", "abbreviations"};
     g_pp_extra_spaces    = new name{"pp", "extra_spaces"};
+    g_pp_preterm         = new name{"pp", "preterm"};
     register_unsigned_option(*g_pp_max_depth, LEAN_DEFAULT_PP_MAX_DEPTH,
                              "(pretty printer) maximum expression depth, after that it will use ellipsis");
     register_unsigned_option(*g_pp_max_steps, LEAN_DEFAULT_PP_MAX_STEPS,
@@ -133,6 +139,8 @@ void initialize_pp_options() {
                          "(pretty printer) display abbreviations (i.e., revert abbreviation expansion when pretty printing)");
     register_bool_option(*g_pp_extra_spaces, LEAN_DEFAULT_PP_EXTRA_SPACES,
                          "(pretty printer) add space after prefix operators and before postfix ones");
+    register_bool_option(*g_pp_preterm, LEAN_DEFAULT_PP_PRETERM,
+                         "(pretty printer) assume the term is a preterm (i.e., a term before elaboration)");
 
     options universes_true(*g_pp_universes, true);
     options full_names_true(*g_pp_full_names, true);
@@ -147,6 +155,7 @@ void initialize_pp_options() {
 }
 
 void finalize_pp_options() {
+    delete g_pp_preterm;
     delete g_pp_extra_spaces;
     delete g_pp_abbreviations;
     delete g_pp_numerals;
@@ -174,6 +183,7 @@ name const & get_pp_metavar_args_name() { return *g_pp_metavar_args; }
 name const & get_pp_purify_metavars_name() { return *g_pp_purify_metavars; }
 name const & get_pp_purify_locals_name() { return *g_pp_purify_locals; }
 name const & get_pp_beta_name() { return *g_pp_beta; }
+name const & get_pp_preterm_name() { return *g_pp_preterm; }
 
 unsigned get_pp_max_depth(options const & opts)       { return opts.get_unsigned(*g_pp_max_depth, LEAN_DEFAULT_PP_MAX_DEPTH); }
 unsigned get_pp_max_steps(options const & opts)       { return opts.get_unsigned(*g_pp_max_steps, LEAN_DEFAULT_PP_MAX_STEPS); }
@@ -190,5 +200,6 @@ bool     get_pp_beta(options const & opts)            { return opts.get_bool(*g_
 bool     get_pp_numerals(options const & opts)        { return opts.get_bool(*g_pp_numerals, LEAN_DEFAULT_PP_NUMERALS); }
 bool     get_pp_abbreviations(options const & opts)   { return opts.get_bool(*g_pp_abbreviations, LEAN_DEFAULT_PP_ABBREVIATIONS); }
 bool     get_pp_extra_spaces(options const & opts)    { return opts.get_bool(*g_pp_extra_spaces, LEAN_DEFAULT_PP_EXTRA_SPACES); }
+bool     get_pp_preterm(options const & opts)         { return opts.get_bool(*g_pp_preterm, LEAN_DEFAULT_PP_PRETERM); }
 list<options> const & get_distinguishing_pp_options() { return *g_distinguishing_pp_options; }
 }

src/library/pp_options.h

@@ -16,6 +16,7 @@ name const & get_pp_metavar_args_name();
 name const & get_pp_purify_metavars_name();
 name const & get_pp_purify_locals_name();
 name const & get_pp_beta_name();
+name const & get_pp_preterm_name();
 
 unsigned get_pp_max_depth(options const & opts);
 unsigned get_pp_max_steps(options const & opts);
@@ -32,6 +33,7 @@ bool     get_pp_purify_locals(options const & opts);
 bool     get_pp_numerals(options const & opts);
 bool     get_pp_abbreviations(options const & opts);
 bool     get_pp_extra_spaces(options const & opts);
+bool     get_pp_preterm(options const & opts);
 list<options> const & get_distinguishing_pp_options();
 
 void initialize_pp_options();

tests/lean/604.lean

@@ -0,0 +1 @@
+print notation dec_trivial

tests/lean/604.lean.expected.out

@@ -0,0 +1 @@
+`dec_trivial`:1024 := of_is_true trivial