feat(frontends/lean/pp): add support for abbreviations in the pretty printer

closes #365

src/frontends/lean/pp.cpp

@@ -23,6 +23,7 @@ Author: Leonardo de Moura
 #include "library/num.h"
 #include "library/let.h"
 #include "library/print.h"
+#include "library/abbreviation.h"
 #include "library/pp_options.h"
 #include "library/constants.h"
 #include "frontends/lean/pp.h"
@@ -274,6 +275,7 @@ void pretty_fn::set_options_core(options const & o) {
     m_purify_locals   = get_pp_purify_locals(o);
     m_beta            = get_pp_beta(o);
     m_numerals        = get_pp_numerals(o);
+    m_abbreviations   = get_pp_abbreviations(o);
     m_num_nat_coe     = m_numerals && !m_coercion && has_coercion_num_nat(m_env);
 }
 
@@ -470,6 +472,11 @@ bool pretty_fn::has_implicit_args(expr const & f) {
 
 auto pretty_fn::pp_app(expr const & e) -> result {
     expr const & fn = app_fn(e);
+    if (m_abbreviations)  {
+        if (auto it = is_abbreviated(m_env, fn)) {
+            return pp_abbreviation(e, *it);
+        }
+    }
     result res_fn = pp_child(fn, max_bp()-1);
     format fn_fmt = res_fn.fmt();
     if (m_implict && !is_app(fn) && has_implicit_args(fn))
@@ -1030,6 +1037,17 @@ auto pretty_fn::pp_notation(expr const & e) -> optional<result> {
     return optional<result>();
 }
 
+auto pretty_fn::pp_abbreviation(expr const & e, name const & abbrev) -> result {
+    declaration const & d = m_env.get(abbrev);
+    unsigned num_univs    = d.get_num_univ_params();
+    buffer<level> ls;
+    for (unsigned i = 0; i < num_univs; i++)
+        ls.push_back(mk_meta_univ(name("?l", i+1)));
+    buffer<expr> args;
+    get_app_args(e, args);
+    return pp(mk_app(mk_constant(abbrev, to_list(ls)), args));
+}
+
 auto pretty_fn::pp(expr const & e) -> result {
     if (m_depth > m_max_depth || m_num_steps > m_max_steps)
         return result(m_unicode ? *g_ellipsis_n_fmt : *g_ellipsis_fmt);
@@ -1045,6 +1063,9 @@ auto pretty_fn::pp(expr const & e) -> result {
     if (is_let(e))          return pp_let(e);
     if (is_typed_expr(e))   return pp(get_typed_expr_expr(e));
     if (is_let_value(e))    return pp(get_let_value_expr(e));
+    if (m_abbreviations)
+        if (auto n = is_abbreviated(m_env, e))
+            return pp_abbreviation(e, *n);
     if (m_numerals)
         if (auto n = to_num(e)) return pp_num(*n);
     if (m_num_nat_coe)

src/frontends/lean/pp.h

@@ -66,6 +66,7 @@ private:
     bool                m_purify_locals;
     bool                m_beta;
     bool                m_numerals;
+    bool                m_abbreviations;
 
     name mk_metavar_name(name const & m);
     name mk_local_name(name const & n, name const & suggested);
@@ -104,6 +105,7 @@ private:
     result pp_explicit(expr const & e);
     result pp_let(expr e);
     result pp_num(mpz const & n);
+    result pp_abbreviation(expr const & e, name const & abbrev);
     void set_options_core(options const & o);
 
 public:

src/library/pp_options.cpp

@@ -59,6 +59,10 @@ Author: Leonardo de Moura
 #define LEAN_DEFAULT_PP_NUMERALS true
 #endif
 
+#ifndef LEAN_DEFAULT_PP_ABBREVIATIONS
+#define LEAN_DEFAULT_PP_ABBREVIATIONS true
+#endif
+
 namespace lean {
 static name * g_pp_max_depth       = nullptr;
 static name * g_pp_max_steps       = nullptr;
@@ -73,6 +77,7 @@ static name * g_pp_purify_metavars = nullptr;
 static name * g_pp_purify_locals   = nullptr;
 static name * g_pp_beta            = nullptr;
 static name * g_pp_numerals        = nullptr;
+static name * g_pp_abbreviations   = nullptr;
 static list<options> * g_distinguishing_pp_options = nullptr;
 
 void initialize_pp_options() {
@@ -89,6 +94,7 @@ void initialize_pp_options() {
     g_pp_purify_locals   = new name{"pp", "purify_locals"};
     g_pp_beta            = new name{"pp", "beta"};
     g_pp_numerals        = new name{"pp", "numerals"};
+    g_pp_abbreviations   = new name{"pp", "abbreviations"};
     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,
@@ -117,6 +123,8 @@ void initialize_pp_options() {
                          "(pretty printer) apply beta-reduction when pretty printing");
     register_bool_option(*g_pp_numerals, LEAN_DEFAULT_PP_NUMERALS,
                          "(pretty printer) display nat/num numerals in decimal notation");
+    register_bool_option(*g_pp_abbreviations, LEAN_DEFAULT_PP_ABBREVIATIONS,
+                         "(pretty printer) display abbreviations (i.e., revert abbreviation expansion when pretty printing)");
 
     options universes_true(*g_pp_universes, true);
     options full_names_true(*g_pp_full_names, true);
@@ -131,6 +139,7 @@ void initialize_pp_options() {
 }
 
 void finalize_pp_options() {
+    delete g_pp_abbreviations;
     delete g_pp_numerals;
     delete g_pp_max_depth;
     delete g_pp_max_steps;
@@ -169,5 +178,6 @@ bool     get_pp_purify_metavars(options const & opts) { return opts.get_bool(*g_
 bool     get_pp_purify_locals(options const & opts)   { return opts.get_bool(*g_pp_purify_locals, LEAN_DEFAULT_PP_PURIFY_LOCALS); }
 bool     get_pp_beta(options const & opts)            { return opts.get_bool(*g_pp_beta, LEAN_DEFAULT_PP_BETA); }
 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); }
 list<options> const & get_distinguishing_pp_options() { return *g_distinguishing_pp_options; }
 }

src/library/pp_options.h

@@ -29,6 +29,7 @@ bool     get_pp_beta(options const & opts);
 bool     get_pp_purify_metavars(options const & opts);
 bool     get_pp_purify_locals(options const & opts);
 bool     get_pp_numerals(options const & opts);
+bool     get_pp_abbreviations(options const & opts);
 list<options> const & get_distinguishing_pp_options();
 
 void initialize_pp_options();