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.