diff --git a/example/ex-algo03.c b/example/ex-algo03.c
new file mode 100644
index 00000000..932f2b30
--- /dev/null
+++ b/example/ex-algo03.c
@@ -0,0 +1,31 @@
+#include "m-dict.h"
+#include "m-array.h"
+#include "m-algo.h"
+#include "m-string.h"
+
+DICT_DEF2(dict, string_t, int)
+#define M_OPL_dict_t() DICT_OPLIST(dict, STRING_OPLIST, M_DEFAULT_OPLIST)
+
+ARRAY_DEF(vector_int, int)
+#define M_OPL_vector_int_t() ARRAY_OPLIST(vector_int)
+
+#define start_with(pattern, item)                \
+  string_start_with_str_p((item).key, (pattern))
+#define get_value(out, item) ((out) = (item).value)
+
+int main(void)
+{
+  int s;
+  M_LET(keys, vector_int_t)
+    M_LET( (m, (STRING_CTE("foo"), 1), (STRING_CTE("bar"), 42), (STRING_CTE("bluez"), 7), (STRING_CTE("stop"), 789) ), tmp, dict_t) {
+ 
+    /* Extract all elements of 'm' that starts with 'b' */
+    ALGO_EXTRACT(tmp, dict_t, m, dict_t, start_with, "b");
+    /* Extract the values of theses elements */
+    ALGO_TRANSFORM(keys, vector_int_t, tmp, dict_t, get_value);
+    /* Sum theses values */
+    ALGO_REDUCE(s, keys, vector_int_t, sum);
+    printf("Sum of elements starting with 'b' is: %d\n", s);
+  }
+  return 0;
+}