feat(library/blast/intros): intros is now a silent step.

src/library/blast/intros.cpp

@@ -4,6 +4,7 @@ Released under Apache 2.0 license as described in the file LICENSE.
 
 Author: Leonardo de Moura
 */
+#include <limits>
 #include "kernel/abstract.h"
 #include "kernel/instantiate.h"
 #include "library/blast/blast.h"
@@ -18,9 +19,11 @@ struct intros_proof_step_cell : public proof_step_cell {
         expr new_pr = mk_proof_lambda(curr_state(), m_new_hs, unfold_hypotheses_ge(curr_state(), pr));
         return action_result::solved(new_pr);
     }
+
+    virtual bool is_silent() const override { return true; }
 };
 
-bool intros_action() {
+bool intros_action(unsigned max) {
     state &  s  = curr_state();
     expr target = whnf(s.get_target());
     if (!is_pi(target))
@@ -28,7 +31,9 @@ bool intros_action() {
     auto pcell = new intros_proof_step_cell();
     s.push_proof_step(pcell);
     buffer<expr> new_hs;
-    while (is_pi(target)) {
+    for (unsigned i = 0; i < max; i++) {
+        if (!is_pi(target))
+            break;
         expr href  = s.mk_hypothesis(binding_name(target), binding_domain(target));
         new_hs.push_back(href);
         target     = whnf(instantiate(binding_body(target), href));
@@ -37,4 +42,8 @@ bool intros_action() {
     s.set_target(target);
     return true;
 }
+
+bool intros_action() {
+    return intros_action(std::numeric_limits<unsigned>::max());
+}
 }}

src/library/blast/intros.h

@@ -7,5 +7,9 @@ Author: Leonardo de Moura
 #pragma once
 namespace lean {
 namespace blast {
+/** \brief Introduce upto \c max hypotheses.
+    Return false if there is nothing to introduce, that is, target is not a Pi-type. */
+bool intros_action(unsigned max);
+/** \brief Keep introducing until target is not a Pi-type. */
 bool intros_action();
 }}