Add micro utilities macros for handling list

m-core.h

@@ -1675,6 +1675,19 @@ M_BEGIN_PROTECTED_CODE
 #define M_FILTER_00(d, item)                                                  \
   M_IF(M_PAIR_1 d(M_PAIR_2 d, item))(item, )
 
+/* Return the HEAD element of a list */
+#define M_HEAD(x, ...)      x
+
+/* Return the HEAD element of the tail of a list */
+#define M_HEAD_2(x, y, ...) y
+
+/* Return the tail sublist of the list (removing the HEAD) */
+#define M_TAIL(x, ...)      __VA_ARGS__
+
+/* Return the tail sublist of the sublist (removing the 2 first elements) */
+#define M_TAIL_2(x, y, ...) __VA_ARGS__
+
+
 /* Concatene two arglists 'a' and 'b',
    handling the case of empty arglist
    handling the cases where the arglists are within parenthesis.

tests/test-mcore.c

@@ -758,6 +758,15 @@ static void test_properties(void)
   assert( M_GET_PROPERTY (OP_PROP(), IT_TYPE ) == 2);
   assert( M_KEYWORD_P( M_GET_PROPERTY (OP_PROP(), INIT_WITH ), priority));
 }
+
+static void test_generic_api(void)
+{
+  assert( M_HEAD(17, 0) == 17);
+  assert( M_TAIL(18, 19) == 19);
+  assert( M_HEAD_2(18, 17, 0) == 17);
+  assert( M_TAIL_2(18, 17, 8) == 8);
+}
+
 int main(void)
 {
   test_cat();
@@ -783,5 +792,6 @@ int main(void)
   test_str_hash();
   test_M_CSTR();
   test_properties();
+  test_generic_api();
   exit(0);
 }