diff --git a/src/counterexample.c b/src/counterexample.c
index ca0f4a0d..bfab304c 100644
--- a/src/counterexample.c
+++ b/src/counterexample.c
@@ -175,6 +175,8 @@ si_bfs_free (si_bfs_node *n)
     }
 }
 
+typedef gl_list_t si_bfs_node_list;
+
 /**
  * start is a state_item such that conflict_sym is an element of FIRSTS of the
  * nonterminal after the dot in start. Because of this, we should be able to
@@ -188,9 +190,10 @@ expand_to_conflict (state_item_number start, symbol_number conflict_sym)
 {
   si_bfs_node *init = si_bfs_new (start, NULL);
 
-  gl_list_t queue = gl_list_create (GL_LINKED_LIST, NULL, NULL,
-                                    (gl_listelement_dispose_fn) si_bfs_free,
-                                    true, 1, (const void **) &init);
+  si_bfs_node_list queue
+    = gl_list_create (GL_LINKED_LIST, NULL, NULL,
+                      (gl_listelement_dispose_fn) si_bfs_free,
+                      true, 1, (const void **) &init);
   si_bfs_node *node = NULL;
   // breadth-first search for a path of productions to the conflict symbol
   while (gl_list_size (queue) > 0)
@@ -274,7 +277,7 @@ expand_to_conflict (state_item_number start, symbol_number conflict_sym)
  */
 static derivation *
 complete_diverging_example (symbol_number conflict_sym,
-                            gl_list_t path, derivation_list derivs)
+                            state_item_list path, derivation_list derivs)
 {
   // The idea is to transfer each pending symbol on the productions
   // associated with the given StateItems to the resulting derivation.
@@ -395,15 +398,15 @@ complete_diverging_example (symbol_number conflict_sym,
 /* Iterate backwards through the shifts of the path in the reduce
    conflict, and find a path of shifts from the shift conflict that
    goes through the same states. */
-static gl_list_t
-nonunifying_shift_path (gl_list_t reduce_path, state_item *shift_conflict)
+static state_item_list
+nonunifying_shift_path (state_item_list reduce_path, state_item *shift_conflict)
 {
   gl_list_node_t tmp = gl_list_add_last (reduce_path, NULL);
   gl_list_node_t next_node = gl_list_previous_node (reduce_path, tmp);
   gl_list_node_t node = gl_list_previous_node (reduce_path, next_node);
   gl_list_remove_node (reduce_path, tmp);
   state_item *si = shift_conflict;
-  gl_list_t result =
+  state_item_list result =
     gl_list_create_empty (GL_LINKED_LIST, NULL, NULL, NULL, true);
   // FIXME: bool paths_merged;
   for (; node != NULL; next_node = node,
@@ -425,10 +428,10 @@ nonunifying_shift_path (gl_list_t reduce_path, state_item *shift_conflict)
 
       // bfs to find a shift to the right state
       si_bfs_node *init = si_bfs_new (si - state_items, NULL);
-      gl_list_t queue =
-        gl_list_create (GL_LINKED_LIST, NULL, NULL,
-                        (gl_listelement_dispose_fn) si_bfs_free,
-                        true, 1, (const void **) &init);
+      si_bfs_node_list queue
+        = gl_list_create (GL_LINKED_LIST, NULL, NULL,
+                          (gl_listelement_dispose_fn) si_bfs_free,
+                          true, 1, (const void **) &init);
       si_bfs_node *sis = NULL;
       state_item *prevsi = NULL;
       while (gl_list_size (queue) > 0)
@@ -493,11 +496,11 @@ nonunifying_shift_path (gl_list_t reduce_path, state_item *shift_conflict)
 static counterexample *
 example_from_path (bool shift_reduce,
                    state_item_number itm2,
-                   gl_list_t shortest_path, symbol_number next_sym)
+                   state_item_list shortest_path, symbol_number next_sym)
 {
   derivation *deriv1 =
     complete_diverging_example (next_sym, shortest_path, NULL);
-  gl_list_t path_2
+  state_item_list path_2
     = shift_reduce
     ? nonunifying_shift_path (shortest_path, &state_items [itm2])
     : shortest_path_from_start (itm2, next_sym);
@@ -583,6 +586,8 @@ search_state_print (search_state *ss)
   putc ('\n', stderr);
 }
 
+typedef gl_list_t search_state_list;
+
 static inline bool
 search_state_list_next (gl_list_iterator_t *it, search_state **ss)
 {
@@ -619,7 +624,7 @@ complete_diverging_examples (search_state *ss,
   derivation *new_derivs[2];
   for (int i = 0; i < 2; ++i)
     {
-      gl_list_t sitems;
+      state_item_list sitems;
       derivation_list derivs;
       parse_state_lists (ss->states[i], &sitems, &derivs);
       new_derivs[i] = complete_diverging_example (next_sym, sitems, derivs);
@@ -635,7 +640,7 @@ complete_diverging_examples (search_state *ss,
  */
 typedef struct
 {
-  gl_list_t states;
+  search_state_list states;
   int complexity;
 } search_state_bundle;
 
@@ -664,6 +669,8 @@ ssb_equals (const search_state_bundle *s1, const search_state_bundle *s2)
   return s1->complexity == s2->complexity;
 }
 
+typedef gl_list_t ssb_list;
+
 static size_t
 visited_hasher (const search_state *ss, size_t max)
 {
@@ -679,7 +686,7 @@ visited_comparator (const search_state *ss1, const search_state *ss2)
 }
 
 /* Priority queue for search states with minimal complexity. */
-static gl_list_t ssb_queue;
+static ssb_list ssb_queue;
 static Hash_table *visited;
 /* The set of parser states on the shortest lookahead-sensitive path. */
 static bitset scp_set = NULL;
@@ -756,12 +763,12 @@ reduction_cost (const parse_state *ps)
   return SHIFT_COST * shifts + PRODUCTION_COST * productions;
 }
 
-static gl_list_t
+static search_state_list
 reduction_step (search_state *ss, const item_number *conflict_item,
                 int parser_state, int rule_len)
 {
   (void) conflict_item; // FIXME: Unused
-  gl_list_t result =
+  search_state_list result =
     gl_list_create_empty (GL_LINKED_LIST, NULL, NULL, NULL, 1);
 
   parse_state *ps = ss->states[parser_state];
@@ -988,14 +995,14 @@ generate_next_states (search_state *ss, state_item *conflict1,
       // prepended further, reduce.
       if (ready1 && ready2)
         {
-          gl_list_t reduced1 = reduction_step (ss, conflict1->item, 0, len1);
+          search_state_list reduced1 = reduction_step (ss, conflict1->item, 0, len1);
           gl_list_add_last (reduced1, ss);
           search_state *red1 = NULL;
           for (gl_list_iterator_t iter = gl_list_iterator (reduced1);
                search_state_list_next (&iter, &red1);
                )
             {
-              gl_list_t reduced2 =
+              search_state_list reduced2 =
                 reduction_step (red1, conflict2->item, 1, len2);
               search_state *red2 = NULL;
               for (gl_list_iterator_t iter2 = gl_list_iterator (reduced2);
@@ -1011,7 +1018,7 @@ generate_next_states (search_state *ss, state_item *conflict1,
         }
       else if (ready1)
         {
-          gl_list_t reduced1 = reduction_step (ss, conflict1->item, 0, len1);
+          search_state_list reduced1 = reduction_step (ss, conflict1->item, 0, len1);
           search_state *red1 = NULL;
           for (gl_list_iterator_t iter = gl_list_iterator (reduced1);
                search_state_list_next (&iter, &red1);
@@ -1021,7 +1028,7 @@ generate_next_states (search_state *ss, state_item *conflict1,
         }
       else if (ready2)
         {
-          gl_list_t reduced2 = reduction_step (ss, conflict2->item, 1, len2);
+          search_state_list reduced2 = reduction_step (ss, conflict2->item, 1, len2);
           search_state *red2 = NULL;
           for (gl_list_iterator_t iter2 = gl_list_iterator (reduced2);
                search_state_list_next (&iter2, &red2);
@@ -1055,7 +1062,7 @@ static counterexample *
 unifying_example (state_item_number itm1,
                   state_item_number itm2,
                   bool shift_reduce,
-                  gl_list_t reduce_path, symbol_number next_sym)
+                  state_item_list reduce_path, symbol_number next_sym)
 {
   state_item *conflict1 = &state_items[itm1];
   state_item *conflict2 = &state_items[itm2];
@@ -1190,7 +1197,7 @@ counterexample_report (state_item_number itm1, state_item_number itm2,
 {
   // Compute the shortest lookahead-sensitive path and associated sets of
   // parser states.
-  gl_list_t shortest_path = shortest_path_from_start (itm1, next_sym);
+  state_item_list shortest_path = shortest_path_from_start (itm1, next_sym);
   bool reduce_prod_reached = false;
   const rule *reduce_rule = item_rule (state_items[itm1].item);
 
@@ -1226,7 +1233,8 @@ counterexample_report_shift_reduce (state_item_number itm1, state_item_number it
 {
   fputs (prefix, out);
   fprintf (out, _("Shift/reduce conflict on token %s:\n"), symbols[next_sym]->tag);
-  if (*prefix)
+  // In the report, print the items.
+  if (*prefix || trace_flag & trace_cex)
     {
       print_state_item (&state_items[itm1], out, prefix);
       print_state_item (&state_items[itm2], out, prefix);
@@ -1254,7 +1262,8 @@ counterexample_report_reduce_reduce (state_item_number itm1, state_item_number i
       }
     fputs (_(":\n"), out);
   }
-  if (*prefix)
+  // In the report, print the items.
+  if (*prefix || trace_flag & trace_cex)
     {
       print_state_item (&state_items[itm1], out, prefix);
       print_state_item (&state_items[itm2], out, prefix);
diff --git a/src/lssi.c b/src/lssi.c
index 86516d58..8448482c 100644
--- a/src/lssi.c
+++ b/src/lssi.c
@@ -82,8 +82,10 @@ lssi_comparator (lssi *s1, lssi *s2)
   return false;
 }
 
+typedef gl_list_t lssi_list;
+
 static inline bool
-append_lssi (lssi *sn, Hash_table *visited, gl_list_t queue)
+append_lssi (lssi *sn, Hash_table *visited, lssi_list queue)
 {
   if (hash_lookup (visited, sn))
     {
@@ -121,7 +123,7 @@ static bitset
 eligible_state_items (state_item *target)
 {
   bitset result = bitset_create (nstate_items, BITSET_FIXED);
-  gl_list_t queue =
+  state_item_list queue =
     gl_list_create (GL_LINKED_LIST, NULL, NULL, NULL, true, 1,
                     (const void **) &target);
   while (gl_list_size (queue) > 0)
@@ -147,7 +149,7 @@ eligible_state_items (state_item *target)
  * this conflict. If optimized is true, only consider parser states
  * that can reach the conflict state.
  */
-gl_list_t
+state_item_list
 shortest_path_from_start (state_item_number target, symbol_number next_sym)
 {
   bitset eligible = eligible_state_items (&state_items[target]);
@@ -159,7 +161,7 @@ shortest_path_from_start (state_item_number target, symbol_number next_sym)
   bitset il = bitset_create (nsyms, BITSET_FIXED);
   bitset_set (il, 0);
   lssi *init = new_lssi (0, NULL, il, true);
-  gl_list_t queue = gl_list_create_empty (GL_LINKED_LIST, NULL, NULL,
+  lssi_list queue = gl_list_create_empty (GL_LINKED_LIST, NULL, NULL,
                                           NULL, true);
   append_lssi (init, visited, queue);
   // breadth-first search
@@ -240,7 +242,7 @@ shortest_path_from_start (state_item_number target, symbol_number next_sym)
       fputs ("Cannot find shortest path to conflict state.", stderr);
       abort ();
     }
-  gl_list_t res =
+  state_item_list res =
     gl_list_create_empty (GL_LINKED_LIST, NULL, NULL, NULL, true);
   for (lssi *sn = n; sn != NULL; sn = sn->parent)
     gl_list_add_first (res, &state_items[sn->si]);
@@ -306,10 +308,10 @@ intersect (bitset ts, bitset syms)
  * Compute a list of state_items that have a production to n with respect
  * to its lookahead
  */
-gl_list_t
+state_item_list
 lssi_reverse_production (const state_item *si, bitset lookahead)
 {
-  gl_list_t result =
+  state_item_list result =
     gl_list_create_empty (GL_LINKED_LIST, NULL, NULL, NULL, true);
   if (SI_TRANSITION (si))
     return result;
diff --git a/src/lssi.h b/src/lssi.h
index dcdb8ef8..6aaf2bc4 100644
--- a/src/lssi.h
+++ b/src/lssi.h
@@ -32,8 +32,8 @@
  * find shortest lookahead-sensitive path of state-items to target such that
  * next_sym is in the follow_L set of target in that position.
 */
-gl_list_t shortest_path_from_start (state_item_number target,
-                                    symbol_number next_sym);
+state_item_list shortest_path_from_start (state_item_number target,
+                                          symbol_number next_sym);
 
 /**
  * Determine if the given terminal is in the given symbol set or can begin
@@ -52,6 +52,6 @@ bool intersect (bitset ts, bitset syms);
  * to this state-item such that the resulting possible lookahead symbols are
  * as given.
  */
-gl_list_t lssi_reverse_production (const state_item *si, bitset lookahead);
+state_item_list lssi_reverse_production (const state_item *si, bitset lookahead);
 
 #endif /* LSSI_H */
diff --git a/src/parse-simulation.c b/src/parse-simulation.c
index ce6ece9a..940a99fe 100644
--- a/src/parse-simulation.c
+++ b/src/parse-simulation.c
@@ -34,7 +34,7 @@ typedef struct parse_state
   struct si_chunk
   {
     // elements newly added in this chunk
-    gl_list_t contents;
+    state_item_list contents;
     // properties of the linked list this chunk represents
     const state_item *head_elt;
     const state_item *tail_elt;
@@ -252,7 +252,7 @@ parse_state_completed_steps (const parse_state *ps, int *shifts, int *production
   while (root_ps->parent)
     root_ps = root_ps->parent;
 
-  gl_list_t sis = root_ps->state_items.contents;
+  state_item_list sis = root_ps->state_items.contents;
   int count = 0;
 
   state_item *last = NULL;
@@ -337,19 +337,17 @@ parser_pop (parse_state *ps, int deriv_index,
   for (int i = 0; i < 4; ++i)
     chunks[i] = gl_list_create_empty (GL_LINKED_LIST, NULL, NULL, NULL, true);
   for (parse_state *pn = ps; pn != NULL; pn = pn->parent)
-    {
-      if (pn->prepend)
-        {
-          gl_list_add_last (chunks[0], pn->state_items.contents);
-          gl_list_add_last (chunks[2], pn->derivs.contents);
-        }
-      else
-        {
-          gl_list_add_first (chunks[1], pn->state_items.contents);
-          gl_list_add_first (chunks[3], pn->derivs.contents);
-        }
-    }
-  gl_list_t popped_derivs = derivation_list_new ();
+    if (pn->prepend)
+      {
+        gl_list_add_last (chunks[0], pn->state_items.contents);
+        gl_list_add_last (chunks[2], pn->derivs.contents);
+      }
+    else
+      {
+        gl_list_add_first (chunks[1], pn->state_items.contents);
+        gl_list_add_first (chunks[3], pn->derivs.contents);
+      }
+  derivation_list popped_derivs = derivation_list_new ();
   gl_list_t ret_chunks[4] = { ret->state_items.contents, NULL,
     ret->derivs.contents, popped_derivs
   };
@@ -390,7 +388,7 @@ parser_pop (parse_state *ps, int deriv_index,
 }
 
 void
-parse_state_lists (parse_state *ps, gl_list_t *sitems,
+parse_state_lists (parse_state *ps, state_item_list *sitems,
                    derivation_list *derivs)
 {
   parse_state *temp = empty_parse_state ();
@@ -431,14 +429,14 @@ nullable_closure (parse_state *ps, state_item *si, parse_state_list state_list)
     }
 }
 
-gl_list_t
+parse_state_list
 simulate_transition (parse_state *ps)
 {
   const state_item *si = ps->state_items.tail_elt;
   symbol_number sym = item_number_as_symbol_number (*si->item);
   // Transition on the same next symbol, taking nullable
   // symbols into account.
-  gl_list_t result = parse_state_list_new ();
+  parse_state_list result = parse_state_list_new ();
   state_item_number si_next = si->trans;
   // check for disabled transition, shouldn't happen
   // as any state_items that lead to these should be
@@ -473,10 +471,10 @@ compatible (symbol_number sym1, symbol_number sym2)
     return false;
 }
 
-gl_list_t
+parse_state_list
 simulate_production (parse_state *ps, symbol_number compat_sym)
 {
-  gl_list_t result = parse_state_list_new ();
+  parse_state_list result = parse_state_list_new ();
   const state_item *si = parse_state_tail (ps);
   if (si->prods)
     {
@@ -504,10 +502,10 @@ simulate_production (parse_state *ps, symbol_number compat_sym)
 // simulates a reduction on the given parse state, conflict_item is the
 // item associated with ps's conflict. symbol_set is a lookahead set this
 // reduction must be compatible with
-gl_list_t
+parse_state_list
 simulate_reduction (parse_state *ps, int rule_len, bitset symbol_set)
 {
-  gl_list_t result = parse_state_list_new ();
+  parse_state_list result = parse_state_list_new ();
 
   int s_size = ps->state_items.total_size;
   int d_size = ps->derivs.total_size;
@@ -537,7 +535,7 @@ simulate_reduction (parse_state *ps, int rule_len, bitset symbol_set)
       // The head state_item is a production item, so we need to prepend
       // with possible source state-items.
       const state_item *head = ps->state_items.head_elt;
-      gl_list_t prev = lssi_reverse_production (head, symbol_set);
+      state_item_list prev = lssi_reverse_production (head, symbol_set);
       // TODO: better understand what causes this case.
       if (gl_list_size (prev) == 0)
         {
@@ -570,10 +568,10 @@ simulate_reduction (parse_state *ps, int rule_len, bitset symbol_set)
   return result;
 }
 
-gl_list_t
+parse_state_list
 parser_prepend (parse_state *ps)
 {
-  gl_list_t res = parse_state_list_new ();
+  parse_state_list res = parse_state_list_new ();
   const state_item *head = ps->state_items.head_elt;
   symbol_number prepend_sym =
     item_number_as_symbol_number (*(head->item - 1));
diff --git a/src/parse-simulation.h b/src/parse-simulation.h
index 6b0549ad..92eea21c 100644
--- a/src/parse-simulation.h
+++ b/src/parse-simulation.h
@@ -113,7 +113,7 @@ int parse_state_length (const parse_state *ps);
 int parse_state_depth (const parse_state *ps);
 
 /* returns the linked lists that the parse state is supposed to represent */
-void parse_state_lists (parse_state *ps, gl_list_t *state_items,
+void parse_state_lists (parse_state *ps, state_item_list *state_items,
                         derivation_list *derivs);
 
 /* various functions that return a list of states based off of
diff --git a/src/state-item.c b/src/state-item.c
index 5542d26b..a3194e16 100644
--- a/src/state-item.c
+++ b/src/state-item.c
@@ -304,7 +304,7 @@ gen_lookaheads (void)
         continue;
 
       bitset lookahead = si->lookahead;
-      gl_list_t queue =
+      state_item_list queue =
         gl_list_create (GL_LINKED_LIST, NULL, NULL, NULL, true, 1,
                         (const void **) &si);
 
@@ -390,7 +390,7 @@ disable_state_item (state_item *si)
 static void
 prune_forward (const state_item *si)
 {
-  gl_list_t queue =
+  state_item_list queue =
     gl_list_create (GL_LINKED_LIST, NULL, NULL, NULL, true, 1,
                     (const void **) &si);
 
@@ -425,7 +425,7 @@ prune_forward (const state_item *si)
 static void
 prune_backward (const state_item *si)
 {
-  gl_list_t queue =
+  state_item_list queue =
     gl_list_create (GL_LINKED_LIST, NULL, NULL, NULL, true, 1,
                     (const void **) &si);
 
diff --git a/src/state-item.h b/src/state-item.h
index d8b46843..dc2b36c8 100644
--- a/src/state-item.h
+++ b/src/state-item.h
@@ -69,6 +69,9 @@ typedef struct
   bitset lookahead;
 } state_item;
 
+// A path of state-items.
+typedef gl_list_t state_item_list;
+
 extern bitsetv firsts;
 # define FIRSTS(sym) firsts[(sym) - ntokens]
 
@@ -92,6 +95,7 @@ void state_items_free (void);
 
 bool production_allowed (const state_item *si, const state_item *next);
 
+// Iterating on a state_item_list.
 static inline bool
 state_item_list_next (gl_list_iterator_t *it, state_item **si)
 {