diff --git a/example/ex-astar.c b/example/ex-astar.c
new file mode 100644
index 00000000..421c6ea5
--- /dev/null
+++ b/example/ex-astar.c
@@ -0,0 +1,119 @@
+//
+// -- An A* pathfinder inspired by the tutorial at Red Blob Games --
+//     https://www.redblobgames.com/pathfinding/a-star/introduction.html
+// Code based on:
+//     https://github.com/glouw/ctl/blob/master/examples/astar.c
+
+#include <stdio.h>
+#include "m-array.h"
+#include "m-string.h"
+#include "m-tuple.h"
+#include "m-prioqueue.h"
+#include "m-dict.h"
+
+// Create a tuple of point, but don't use its priority field for comparison.
+TUPLE_DEF2( point, (x, int), (y, int), (priority, int, M_OPEXTEND( M_OPL_int(), CMP(0), HASH(0), EQUAL(0) ) ) )
+#define M_OPL_point_t() TUPLE_OPLIST(point, M_OPL_int(), M_OPL_int(), M_OPL_int())
+static inline int point_cmp_prio(const point_t a, const point_t b)
+{
+  return a->priority < b->priority ? -1 : a->priority > b->priority;
+}
+PRIOQUEUE_DEF(prio_point, point_t, M_OPEXTEND(M_OPL_point_t(), CMP(point_cmp_prio) ) )
+#define M_OPL_prio_point_t() PRIOQUEUE_OPLIST(prio_point, M_OPL_point_t() )
+ARRAY_DEF(array_point, point_t)
+#define M_OPL_array_point_t() ARRAY_OPLIST(array_point, M_OPL_point_t() )
+DICT_DEF2(cost_point, point_t, int)
+#define M_OPL_cost_point_t() DICT_OPLIST(cost_point, M_OPL_point_t(), M_OPL_int())
+DICT_DEF2(step_point, point_t, point_t)
+#define M_OPL_step_point_t() DICT_OPLIST(step_point, M_OPL_point_t(), M_OPL_point_t())
+
+static inline int point_index(const point_t p, int width)
+{
+  return p->x + width * p->y;
+}
+
+static inline void point_set_from(point_t p, const string_t maze, int width, const char pattern[])
+{
+  size_t s = string_search_str(maze, pattern);
+  point_emplace(p, s % width, s / width , 0);
+}
+
+static void astar(array_point_t path, const string_t maze, int width)
+{
+  M_LET(front, prio_point_t)
+    M_LET(from, step_point_t)
+    M_LET(costs, cost_point_t)
+    M_LET(start, goal, current, next, point_t)
+    {
+      point_set_from(start, maze, width, "@");
+      point_set_from(goal, maze, width, "!");
+      cost_point_set_at(costs, start, 0);
+      prio_point_push(front, start);
+      while (!prio_point_empty_p(front)) {
+        prio_point_pop(&current, front);
+        if (point_equal_p(current, goal))
+          break;
+        const struct { int x; int y; } deltas[] = {
+          { -1, +1 }, { 0, +1 }, { 1, +1 },
+          { -1,  0 }, /* ~ ~ */  { 1,  0 },
+          { -1, -1 }, { 0, -1 }, { 1, -1 },
+        };
+        for (size_t i = 0; i < 8; i++) {
+          point_emplace(next, current->x + deltas[i].x, current->y + deltas[i].y, 0);
+          if (string_get_char(maze, point_index(next, width)) != '#') {
+            int *new_cost = cost_point_get(costs, current);
+            int *cost     = cost_point_get(costs, next);
+            if (cost == NULL || *new_cost < *cost) {
+              cost_point_set_at(costs, next, *new_cost);
+              next->priority = *new_cost + abs(goal->x - next->x) + abs(goal->y - next->y);
+              prio_point_push(front, next);
+              step_point_set_at(from, next, current);
+            }
+          }
+        }
+      }     
+      point_set(current, goal);
+      while (!point_equal_p(current, start)) {
+        array_point_push_back(path, current);
+        point_set(current, *step_point_get(from, current));
+      }
+      array_point_push_back(path, start);
+    }
+}
+
+int main(void)
+{
+  M_LET( (maze, 
+          ("#########################################################################\n"
+           "#   #               #               #           #                   #   #\n"
+           "#   #   #########   #   #####   #########   #####   #####   #####   # ! #\n"
+           "#               #       #   #           #           #   #   #       #   #\n"
+           "#########   #   #########   #########   #####   #   #   #   #########   #\n"
+           "#       #   #               #           #   #   #   #   #           #   #\n"
+           "#   #   #############   #   #   #########   #####   #   #########   #   #\n"
+           "#   #               #   #   #       #           #           #       #   #\n"
+           "#   #############   #####   #####   #   #####   #########   #   #####   #\n"
+           "#           #       #   #       #   #       #           #   #           #\n"
+           "#   #####   #####   #   #####   #   #########   #   #   #   #############\n"
+           "#       #       #   #   #       #       #       #   #   #       #       #\n"
+           "#############   #   #   #   #########   #   #####   #   #####   #####   #\n"
+           "#           #   #           #       #   #       #   #       #           #\n"
+           "#   #####   #   #########   #####   #   #####   #####   #############   #\n"
+           "#   #       #           #           #       #   #   #               #   #\n"
+           "#   #   #########   #   #####   #########   #   #   #############   #   #\n"
+           "#   #           #   #   #   #   #           #               #   #       #\n"
+           "#   #########   #   #   #   #####   #########   #########   #   #########\n"
+           "#   #       #   #   #           #           #   #       #               #\n"
+           "# @ #   #####   #####   #####   #########   #####   #   #########   #   #\n"
+           "#   #                   #           #               #               #   #\n"
+           "#########################################################################\n")), string_t)
+    M_LET(path, array_point_t)
+    {
+      int width = string_search_str(maze, "\n") + 1;
+      astar(path, maze, width);
+      for M_EACH(it, path, array_point_t) {
+          string_set_char(maze, point_index(*it, width), 'x');
+        }
+      printf("%s", string_get_cstr(maze));
+    }
+}