diff --git a/README.md b/README.md
index 61379c2a..57e383ab 100644
--- a/README.md
+++ b/README.md
@@ -6206,12 +6206,26 @@ when the bracket associated to the M\_LET go out of scope.
 
 If 'var1' (resp. var2, ...) has the form (v1, arguments...),
 then the variable 'v1' will be initialized with the 
-contains of 'arguments...' given to the specialized initializer 
-operator INIT\_WITH
-(and not the empty initializer INIT operator).
-An argument shall not contain any comma or it shall be
+contains of 'arguments...'.
+If 'arguments' is within parenthesis
+or if there is more one argument
+or if the property LET\_AS\_INIT\_WITH is defined,
+it will use the operator INIT\_WITH if it exists to emplace the variable
+with the given arguments (The arguments are expected to be compatible with
+the INIT\_WITH operator).
+Otherwise it will use the operator INIT\_SET (argument is expected
+to be the same type as the initialized type).
+In both cases, the empty initializer INIT operator is not called.
+
+LIMITATION:
+An argument shall not contain any comma or it shall be put
 between parenthesis. In particular, if the argument is a compound
-litteral the full compound litteral shall be put between parenthesis.
+litteral the full compound litteral shall be put between parenthesis
+and casted to the right type outside the parenthesis (due to the conflict
+with the INIT\_WITH detection it is needed to put something outside the
+parenthesis like a cast).
+
+An argument shall not have any post effect when it is evaluated.
 
 There shall be at most one M\_LET macro per line of source code.
 
@@ -6219,6 +6233,7 @@ Example:
 
      M_LET(a, STRING_OPLIST) { do something with a }  or
      M_LET(a, b, c, string_t) { do something with a, b & c }
+     M_LET( (a, ("Hello")), string_t) { do something with a }
 
 NOTE: The user code shall not perform a return or a goto (or longjmp) outside the {} or a call to an exit function
 otherwise the clear code of the object won't be called .
diff --git a/doc/API.txt b/doc/API.txt
index cab0b797..ebc7b1f4 100644
--- a/doc/API.txt
+++ b/doc/API.txt
@@ -60,8 +60,11 @@ V0.4.*: * The order of a list initialized using M_LET is reversed
 V0.5.*: * M_INVERT is renamed into M_REVERSE to be more coherent with the REVERSE operator.
           M_INVERT is marked as obsolete.
         * Remove _it_to_p method of B+TREE / RB-TREE as it has been deprecated.
-        * Remove ALGO_INIT_VA & M_ALG0_LET_INIT_VAI of m-algo as it has been deprecated. Use of M_LET instead.
+        * Remove ALGO_INIT_VA & M_ALG0_LET_INIT_VAI of m-algo as it has been deprecated (Use of M_LET instead).
         * Some Internal name of user modifiable macros have been renamed to be properly 
         customizable by the user.
-        * Rename M_HASH_SEED into M_USE_HASH_SEED as it is a user macro.
+        * Rename M_HASH_SEED into M_USE_HASH_SEED (as it is a user macro).
+        * M_LET: for initialization of variable with arguments, if there is only one argument, 
+        it will default to use INIT_SET instead of INIT_WITH. Encapsulate the argument between ()
+        to force use of INIT_WITH.
         
\ No newline at end of file
diff --git a/example/ex-string03.c b/example/ex-string03.c
new file mode 100644
index 00000000..12aeaa5f
--- /dev/null
+++ b/example/ex-string03.c
@@ -0,0 +1,44 @@
+#include <stdio.h>
+#include "m-string.h"
+#include "m-dict.h"
+#include "m-array.h"
+
+/* Definition of an associative map string_t --> size_t */
+DICT_DEF2(dict_str, string_t, size_t)
+#define M_OPL_dict_str_t() DICT_OPLIST(dict_str, STRING_OPLIST, M_DEFAULT_OPLIST)
+
+/* Definition of an array of string_t */
+ARRAY_DEF(vector_str, string_t)
+#define M_OPL_vector_str_t() ARRAY_OPLIST(vector_str, STRING_OPLIST)
+
+int main(void)
+{
+    // Construct an array of string, performing a convertion of the C const char *
+    // into a proper string_t at real time and push then into a dynamic array
+    // that is declared, initialized and cleared.
+    M_LET( (words, ("This"), ("is"), ("a"), ("useless"), ("sentence"), ("."),
+                    ("It"), ("is"), ("used"), ("a"), ("bit"), ("to"), ("count"), ("words"), (".") ),
+                    vector_str_t) {
+        // Print the arrays.
+        printf("The words are: ");
+        vector_str_out_str(stdout, words);
+        printf("\n");
+
+        // Count the words.
+        M_LET(map, dict_str_t) {
+            // Count the words:
+            for M_EACH(w, words, vector_str_t) {
+                (*dict_str_get_at(map, *w)) ++;
+            }
+
+            // Print the count:
+            for M_EACH(p, map, dict_str_t) {
+#if (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L)            
+                M_PRINT(p->value, " occurences of ", p->key, "\n");
+#else
+                printf ("%zu occurences of %s\n", p->value, string_get_cstr(p->key));
+#endif
+            }
+        }
+    }
+}
diff --git a/m-array.h b/m-array.h
index 82cd0322..94018d5c 100644
--- a/m-array.h
+++ b/m-array.h
@@ -76,7 +76,7 @@
 #define M_ARRA4_OPLIST_P3(name, oplist)                                       \
   (INIT(M_C(name, _init))                                                     \
    ,M_IF_METHOD2(INIT_SET,SET, oplist)(INIT_SET(M_C(name, _init_set)),)       \
-   ,M_IF_METHOD(INIT_SET, oplist)(INIT_WITH(API_1(M_INIT_VAI)),)              \
+   ,M_IF_METHOD(INIT_SET, oplist)(INIT_WITH(API_1(M_INIT_WITH_VAI)),)         \
    ,M_IF_METHOD2(INIT_SET,SET, oplist)(SET(M_C(name, _set)), )                \
    ,CLEAR(M_C(name, _clear))                                                  \
    ,INIT_MOVE(M_C(name, _init_move))                                          \
diff --git a/m-core.h b/m-core.h
index e9e114ef..77e30643 100644
--- a/m-core.h
+++ b/m-core.h
@@ -1220,9 +1220,62 @@ M_BEGIN_PROTECTED_CODE
 
 /* Map a macro to all given arguments with one additional fixed data (non recursive version) */
 /* Example: M_MAP2(f, data, a, b, c) ==> f(data,a) f(data,b) f(data,c) */
-#define M_MAP2(f, d, ...)  M_MAP2I(M_C(M_MAP2B_, M_NARGS(__VA_ARGS__)), f, d, __VA_ARGS__)
+#define M_MAP2(f, d, ...)  M_MAP2I(M_C(M_MAP2I_, M_NARGS(__VA_ARGS__)), f, d, __VA_ARGS__)
 #define M_MAP2I(F,...)     F (__VA_ARGS__)
 
+#define M_MAP2I_1(f, d, _1) f(d, _1) 
+#define M_MAP2I_2(f, d, _1, _2) f(d, _1) f(d, _2) 
+#define M_MAP2I_3(f, d, _1, _2, _3) f(d, _1) f(d, _2) f(d, _3) 
+#define M_MAP2I_4(f, d, _1, _2, _3, _4) f(d, _1) f(d, _2) f(d, _3) f(d, _4) 
+#define M_MAP2I_5(f, d, _1, _2, _3, _4, _5) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) 
+#define M_MAP2I_6(f, d, _1, _2, _3, _4, _5, _6) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) 
+#define M_MAP2I_7(f, d, _1, _2, _3, _4, _5, _6, _7) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) 
+#define M_MAP2I_8(f, d, _1, _2, _3, _4, _5, _6, _7, _8) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) 
+#define M_MAP2I_9(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) 
+#define M_MAP2I_10(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) 
+#define M_MAP2I_11(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) 
+#define M_MAP2I_12(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) 
+#define M_MAP2I_13(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) 
+#define M_MAP2I_14(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) 
+#define M_MAP2I_15(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) 
+#define M_MAP2I_16(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) 
+#define M_MAP2I_17(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) 
+#define M_MAP2I_18(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) 
+#define M_MAP2I_19(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) 
+#define M_MAP2I_20(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) 
+#define M_MAP2I_21(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) 
+#define M_MAP2I_22(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) 
+#define M_MAP2I_23(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) 
+#define M_MAP2I_24(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) 
+#define M_MAP2I_25(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) 
+#define M_MAP2I_26(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) f(d, _26) 
+#define M_MAP2I_27(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) f(d, _26) f(d, _27) 
+#define M_MAP2I_28(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) f(d, _26) f(d, _27) f(d, _28) 
+#define M_MAP2I_29(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) f(d, _26) f(d, _27) f(d, _28) f(d, _29) 
+#define M_MAP2I_30(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) f(d, _26) f(d, _27) f(d, _28) f(d, _29) f(d, _30) 
+#define M_MAP2I_31(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) f(d, _26) f(d, _27) f(d, _28) f(d, _29) f(d, _30) f(d, _31) 
+#define M_MAP2I_32(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31, _32) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) f(d, _26) f(d, _27) f(d, _28) f(d, _29) f(d, _30) f(d, _31) f(d, _32) 
+#define M_MAP2I_33(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31, _32, _33) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) f(d, _26) f(d, _27) f(d, _28) f(d, _29) f(d, _30) f(d, _31) f(d, _32) f(d, _33) 
+#define M_MAP2I_34(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31, _32, _33, _34) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) f(d, _26) f(d, _27) f(d, _28) f(d, _29) f(d, _30) f(d, _31) f(d, _32) f(d, _33) f(d, _34) 
+#define M_MAP2I_35(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31, _32, _33, _34, _35) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) f(d, _26) f(d, _27) f(d, _28) f(d, _29) f(d, _30) f(d, _31) f(d, _32) f(d, _33) f(d, _34) f(d, _35) 
+#define M_MAP2I_36(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31, _32, _33, _34, _35, _36) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) f(d, _26) f(d, _27) f(d, _28) f(d, _29) f(d, _30) f(d, _31) f(d, _32) f(d, _33) f(d, _34) f(d, _35) f(d, _36) 
+#define M_MAP2I_37(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31, _32, _33, _34, _35, _36, _37) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) f(d, _26) f(d, _27) f(d, _28) f(d, _29) f(d, _30) f(d, _31) f(d, _32) f(d, _33) f(d, _34) f(d, _35) f(d, _36) f(d, _37) 
+#define M_MAP2I_38(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31, _32, _33, _34, _35, _36, _37, _38) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) f(d, _26) f(d, _27) f(d, _28) f(d, _29) f(d, _30) f(d, _31) f(d, _32) f(d, _33) f(d, _34) f(d, _35) f(d, _36) f(d, _37) f(d, _38) 
+#define M_MAP2I_39(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31, _32, _33, _34, _35, _36, _37, _38, _39) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) f(d, _26) f(d, _27) f(d, _28) f(d, _29) f(d, _30) f(d, _31) f(d, _32) f(d, _33) f(d, _34) f(d, _35) f(d, _36) f(d, _37) f(d, _38) f(d, _39) 
+#define M_MAP2I_40(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31, _32, _33, _34, _35, _36, _37, _38, _39, _40) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) f(d, _26) f(d, _27) f(d, _28) f(d, _29) f(d, _30) f(d, _31) f(d, _32) f(d, _33) f(d, _34) f(d, _35) f(d, _36) f(d, _37) f(d, _38) f(d, _39) f(d, _40) 
+#define M_MAP2I_41(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31, _32, _33, _34, _35, _36, _37, _38, _39, _40, _41) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) f(d, _26) f(d, _27) f(d, _28) f(d, _29) f(d, _30) f(d, _31) f(d, _32) f(d, _33) f(d, _34) f(d, _35) f(d, _36) f(d, _37) f(d, _38) f(d, _39) f(d, _40) f(d, _41) 
+#define M_MAP2I_42(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31, _32, _33, _34, _35, _36, _37, _38, _39, _40, _41, _42) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) f(d, _26) f(d, _27) f(d, _28) f(d, _29) f(d, _30) f(d, _31) f(d, _32) f(d, _33) f(d, _34) f(d, _35) f(d, _36) f(d, _37) f(d, _38) f(d, _39) f(d, _40) f(d, _41) f(d, _42) 
+#define M_MAP2I_43(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31, _32, _33, _34, _35, _36, _37, _38, _39, _40, _41, _42, _43) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) f(d, _26) f(d, _27) f(d, _28) f(d, _29) f(d, _30) f(d, _31) f(d, _32) f(d, _33) f(d, _34) f(d, _35) f(d, _36) f(d, _37) f(d, _38) f(d, _39) f(d, _40) f(d, _41) f(d, _42) f(d, _43) 
+#define M_MAP2I_44(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31, _32, _33, _34, _35, _36, _37, _38, _39, _40, _41, _42, _43, _44) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) f(d, _26) f(d, _27) f(d, _28) f(d, _29) f(d, _30) f(d, _31) f(d, _32) f(d, _33) f(d, _34) f(d, _35) f(d, _36) f(d, _37) f(d, _38) f(d, _39) f(d, _40) f(d, _41) f(d, _42) f(d, _43) f(d, _44) 
+#define M_MAP2I_45(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31, _32, _33, _34, _35, _36, _37, _38, _39, _40, _41, _42, _43, _44, _45) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) f(d, _26) f(d, _27) f(d, _28) f(d, _29) f(d, _30) f(d, _31) f(d, _32) f(d, _33) f(d, _34) f(d, _35) f(d, _36) f(d, _37) f(d, _38) f(d, _39) f(d, _40) f(d, _41) f(d, _42) f(d, _43) f(d, _44) f(d, _45) 
+#define M_MAP2I_46(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31, _32, _33, _34, _35, _36, _37, _38, _39, _40, _41, _42, _43, _44, _45, _46) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) f(d, _26) f(d, _27) f(d, _28) f(d, _29) f(d, _30) f(d, _31) f(d, _32) f(d, _33) f(d, _34) f(d, _35) f(d, _36) f(d, _37) f(d, _38) f(d, _39) f(d, _40) f(d, _41) f(d, _42) f(d, _43) f(d, _44) f(d, _45) f(d, _46) 
+#define M_MAP2I_47(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31, _32, _33, _34, _35, _36, _37, _38, _39, _40, _41, _42, _43, _44, _45, _46, _47) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) f(d, _26) f(d, _27) f(d, _28) f(d, _29) f(d, _30) f(d, _31) f(d, _32) f(d, _33) f(d, _34) f(d, _35) f(d, _36) f(d, _37) f(d, _38) f(d, _39) f(d, _40) f(d, _41) f(d, _42) f(d, _43) f(d, _44) f(d, _45) f(d, _46) f(d, _47) 
+#define M_MAP2I_48(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31, _32, _33, _34, _35, _36, _37, _38, _39, _40, _41, _42, _43, _44, _45, _46, _47, _48) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) f(d, _26) f(d, _27) f(d, _28) f(d, _29) f(d, _30) f(d, _31) f(d, _32) f(d, _33) f(d, _34) f(d, _35) f(d, _36) f(d, _37) f(d, _38) f(d, _39) f(d, _40) f(d, _41) f(d, _42) f(d, _43) f(d, _44) f(d, _45) f(d, _46) f(d, _47) f(d, _48) 
+#define M_MAP2I_49(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31, _32, _33, _34, _35, _36, _37, _38, _39, _40, _41, _42, _43, _44, _45, _46, _47, _48, _49) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) f(d, _26) f(d, _27) f(d, _28) f(d, _29) f(d, _30) f(d, _31) f(d, _32) f(d, _33) f(d, _34) f(d, _35) f(d, _36) f(d, _37) f(d, _38) f(d, _39) f(d, _40) f(d, _41) f(d, _42) f(d, _43) f(d, _44) f(d, _45) f(d, _46) f(d, _47) f(d, _48) f(d, _49) 
+#define M_MAP2I_50(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31, _32, _33, _34, _35, _36, _37, _38, _39, _40, _41, _42, _43, _44, _45, _46, _47, _48, _49, _50) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) f(d, _26) f(d, _27) f(d, _28) f(d, _29) f(d, _30) f(d, _31) f(d, _32) f(d, _33) f(d, _34) f(d, _35) f(d, _36) f(d, _37) f(d, _38) f(d, _39) f(d, _40) f(d, _41) f(d, _42) f(d, _43) f(d, _44) f(d, _45) f(d, _46) f(d, _47) f(d, _48) f(d, _49) f(d, _50) 
+#define M_MAP2I_51(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31, _32, _33, _34, _35, _36, _37, _38, _39, _40, _41, _42, _43, _44, _45, _46, _47, _48, _49, _50, _51) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) f(d, _26) f(d, _27) f(d, _28) f(d, _29) f(d, _30) f(d, _31) f(d, _32) f(d, _33) f(d, _34) f(d, _35) f(d, _36) f(d, _37) f(d, _38) f(d, _39) f(d, _40) f(d, _41) f(d, _42) f(d, _43) f(d, _44) f(d, _45) f(d, _46) f(d, _47) f(d, _48) f(d, _49) f(d, _50) f(d, _51) 
+#define M_MAP2I_52(f, d, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31, _32, _33, _34, _35, _36, _37, _38, _39, _40, _41, _42, _43, _44, _45, _46, _47, _48, _49, _50, _51, _52) f(d, _1) f(d, _2) f(d, _3) f(d, _4) f(d, _5) f(d, _6) f(d, _7) f(d, _8) f(d, _9) f(d, _10) f(d, _11) f(d, _12) f(d, _13) f(d, _14) f(d, _15) f(d, _16) f(d, _17) f(d, _18) f(d, _19) f(d, _20) f(d, _21) f(d, _22) f(d, _23) f(d, _24) f(d, _25) f(d, _26) f(d, _27) f(d, _28) f(d, _29) f(d, _30) f(d, _31) f(d, _32) f(d, _33) f(d, _34) f(d, _35) f(d, _36) f(d, _37) f(d, _38) f(d, _39) f(d, _40) f(d, _41) f(d, _42) f(d, _43) f(d, _44) f(d, _45) f(d, _46) f(d, _47) f(d, _48) f(d, _49) f(d, _50) f(d, _51) f(d, _52) 
+
 /* Duplicate for GET_METHOD as it may be called in context where a M_MAP2 is in progress (for oplist).
    NOTE: Increase number of arguments to 76 due to the number of available methods.
    NOTE: Rewrite with another approach much more verbose but also much faster for the compiler.
@@ -1684,8 +1737,10 @@ M_BEGIN_PROTECTED_CODE
 
 /* Remove the parenthesis if needed
    (internal macro) */
-#define M_REMOVE_PARENTHESIS(list)                                            \
-  M_IF(M_PARENTHESIS_P(list))( M_OPFLAT list, list)
+#define M_REMOVE_PARENTHESIS(...)                                             \
+  M_IF(M_PARENTHESIS_P(__VA_ARGS__))(M_REMOVE_PARENTHESIS_2, M_REMOVE_PARENTHESIS_3)(__VA_ARGS__)
+#define M_REMOVE_PARENTHESIS_2(...) M_OPFLAT __VA_ARGS__
+#define M_REMOVE_PARENTHESIS_3(...) __VA_ARGS__
 
 /* Return the input (delay evaluation) */
 #define M_ID(...)                 __VA_ARGS__
@@ -2724,6 +2779,9 @@ static inline size_t m_core_cstr_hash(const char str[])
 #define M_LIMITS_LIMITS(a)       ,a,
 #define M_PROPERTIES_PROPERTIES(a) ,a,
 
+// Properties only
+#define M_LET_AS_INIT_WITH_LET_AS_INIT_WITH(a) ,a,
+
 /* From an oplist - an unorded list of methods : like "INIT(mpz_init),CLEAR(mpz_clear),SET(mpz_set)" -
    Return the given method in the oplist or the default method.
    Example: 
@@ -2879,9 +2937,13 @@ static inline size_t m_core_cstr_hash(const char str[])
 
 /* API transformation support:
    transform the call to the method into the supported API by the method.
-   Example of usage in oplist: ( INIT_WITH(API_1(method)) ) */
+   Example of usage in oplist: ( INIT_WITH(API_1(method)) )
+   NOTE: It uses M_RET_ARG3 instead of M_RET_ARG2 since M_GET_METHOD
+   uses M_RET_ARG2: to be able to use M_GET_METHOD within a M_APPLY_API
+   we need another macro to avoid being marked.
+*/
 #define M_APPLY_API(method, oplist, ...)                                      \
-  M_RET_ARG2(M_C(M_OPLAPI_INDIRECT_, method)(M_C(M_OPLAPI_EXTRACT_,method),oplist,__VA_ARGS__), method(__VA_ARGS__),)
+  M_RET_ARG3( , M_C(M_OPLAPI_INDIRECT_, method)(M_C(M_OPLAPI_EXTRACT_,method),oplist,__VA_ARGS__), method(__VA_ARGS__),)
 
 /* API Transformation :
    0: Method has been disable. It shall not be called. Raised an error.
@@ -2889,16 +2951,18 @@ static inline size_t m_core_cstr_hash(const char str[])
    API_2: by addr for first argument, API_3: oplist given,
    API_4 :by affectation for first argument, 5: API_by affectation + oplist
    API_6 :by addr for two arguments, 5: API_by address for both + oplist
+
+   NOTE: It starts by a comma, to ack the success of the transformation.
 */
 #define M_OPLAPI_ERROR(method, oplist, ...)  , M_STATIC_FAILURE(M_LIB_DISABLED_METHOD, "The method has been explictly disabled for the requested operator, yet it has been called by the container")
-#define M_OPLAPI_0(method, oplist, ...)      , method(__VA_ARGS__)
-#define M_OPLAPI_1(method, oplist, ...)      , method(oplist, __VA_ARGS__)
-#define M_OPLAPI_2(method, oplist, ...)      , method(& __VA_ARGS__)
-#define M_OPLAPI_3(method, oplist, ...)      , method(oplist, &__VA_ARGS__)
-#define M_OPLAPI_4(method, oplist, x, ...)   , x = method(__VA_ARGS__)
-#define M_OPLAPI_5(method, oplist, x, ...)   , x = method(oplist, __VA_ARGS__)
-#define M_OPLAPI_6(method, oplist, x, ...)   , method(&x, &__VA_ARGS__)
-#define M_OPLAPI_7(method, oplist, x, ...)   , method(oplist, &x, &__VA_ARGS__)
+#define M_OPLAPI_0(method, oplist, ...)      , M_DELAY3(method)(__VA_ARGS__)
+#define M_OPLAPI_1(method, oplist, ...)      , M_DELAY3(method)(oplist, __VA_ARGS__)
+#define M_OPLAPI_2(method, oplist, ...)      , M_DELAY3(method)(& __VA_ARGS__)
+#define M_OPLAPI_3(method, oplist, ...)      , M_DELAY3(method)(oplist, &__VA_ARGS__)
+#define M_OPLAPI_4(method, oplist, x, ...)   , x = M_DELAY3(method)(__VA_ARGS__)
+#define M_OPLAPI_5(method, oplist, x, ...)   , x = M_DELAY3(method)(oplist, __VA_ARGS__)
+#define M_OPLAPI_6(method, oplist, x, ...)   , M_DELAY3(method)(&x, &__VA_ARGS__)
+#define M_OPLAPI_7(method, oplist, x, ...)   , M_DELAY3(method)(oplist, &x, &__VA_ARGS__)
 /* API transformation support for indirection */
 #define M_OPLAPI_INDIRECT_0          M_OPLAPI_ERROR
 #define M_OPLAPI_INDIRECT_API_0(...) M_OPLAPI_0
@@ -3097,6 +3161,7 @@ static inline size_t m_core_cstr_hash(const char str[])
   (INIT(M_INIT_DEFAULT), INIT_SET(M_SET_DEFAULT), SET(M_SET_DEFAULT),         \
    CLEAR(M_NOTHING_DEFAULT), EQUAL(M_EQUAL_DEFAULT), CMP(M_CMP_DEFAULT),      \
    INIT_MOVE(M_MOVE_DEFAULT), MOVE(M_MOVE_DEFAULT) ,                          \
+   CLEAN(M_INIT_DEFAULT),                                                     \
    ADD(M_ADD_DEFAULT), SUB(M_SUB_DEFAULT),                                    \
    MUL(M_MUL_DEFAULT), DIV(M_DIV_DEFAULT),                                    \
    HASH(M_HASH_DEFAULT), SWAP(M_SWAP_DEFAULT) ,                               \
@@ -3109,6 +3174,7 @@ static inline size_t m_core_cstr_hash(const char str[])
   (INIT(M_INIT_DEFAULT), INIT_SET(M_SET_DEFAULT), SET(M_SET_DEFAULT),         \
    CLEAR(M_NOTHING_DEFAULT), EQUAL(M_EQUAL_DEFAULT), CMP(M_CMP_DEFAULT),      \
    INIT_MOVE(M_MOVE_DEFAULT), MOVE(M_MOVE_DEFAULT) ,                          \
+   CLEAN(M_INIT_DEFAULT),                                                     \
    ADD(M_ADD_DEFAULT), SUB(M_SUB_DEFAULT),                                    \
    MUL(M_MUL_DEFAULT), DIV(M_DIV_DEFAULT),                                    \
    HASH(M_HASH_DEFAULT), SWAP(M_SWAP_DEFAULT) ,                               \
@@ -3121,6 +3187,7 @@ static inline size_t m_core_cstr_hash(const char str[])
   (INIT(M_INIT_DEFAULT), INIT_SET(M_SET_DEFAULT), SET(M_SET_DEFAULT),         \
    CLEAR(M_NOTHING_DEFAULT), EQUAL(M_EQUAL_DEFAULT), CMP(M_CMP_DEFAULT),      \
    INIT_MOVE(M_MOVE_DEFAULT), MOVE(M_MOVE_DEFAULT) ,                          \
+   CLEAN(M_INIT_DEFAULT),                                                     \
    ADD(M_ADD_DEFAULT), SUB(M_SUB_DEFAULT),                                    \
    MUL(M_MUL_DEFAULT), DIV(M_DIV_DEFAULT),                                    \
    HASH(M_HASH_DEFAULT), SWAP(M_SWAP_DEFAULT)                         )
@@ -3266,7 +3333,7 @@ m_core_parse2_enum (const char str[], const char **endptr)
 /* Return the content of a property named 'propname' 
    in the PROPERTIES field of oplist
    or 0, if it is not defined */
-#define M_GET_OPPROPERTY(oplist, propname)                                    \
+#define M_GET_PROPERTY(oplist, propname)                                      \
   M_GET_METHOD (propname, 0, M_OPFLAT M_GET_PROPERTIES oplist)
 
 /* Test if a method is present in an oplist.
@@ -3420,7 +3487,7 @@ m_core_parse2_enum (const char str[], const char **endptr)
    Second argument is the container to iterate.
    Third argument can be the oplist of the list or the type of the list if a global
    oplist has been recorded.
-   USAGE: for M_EACH(item, list, LIST_OPLIST) { M_LETaction; } 
+   USAGE: for M_EACH(item, list, LIST_OPLIST) { action; } 
 */
 #define M_EACH(item, container, oplist)                                       \
   M_EACHI_OPLIST(item, container, M_GLOBAL_OPLIST(oplist))
@@ -3502,8 +3569,15 @@ m_core_parse2_enum (const char str[], const char **endptr)
   for(M_GET_TYPE oplist name;                                                 \
       cont && (M_LETI_SINGLE2_INIT(oplist, name, __VA_ARGS__), true);         \
       (M_CALL_CLEAR(oplist, name), cont = false))
+// 6c. Use of INIT_SET or INIT_WITH.
 #define M_LETI_SINGLE2_INIT(oplist, name, ...)                                \
-  M_IF_METHOD(INIT_WITH,oplist)(M_CALL_INIT_WITH, M_CALL_INIT_SET)(oplist, name, __VA_ARGS__)
+  M_IF_METHOD(INIT_WITH,oplist)(M_LETI_SINGLE3_INIT, M_CALL_INIT_SET)(oplist, name, __VA_ARGS__)
+#define M_LETI_SINGLE3_INIT(oplist, name, ...)                                \
+  M_IF(M_NOTEQUAL( M_NARGS(__VA_ARGS__), 1))(M_CALL_INIT_WITH, M_LETI_SINGLE4_INIT)(oplist, name, __VA_ARGS__)
+#define M_LETI_SINGLE4_INIT(oplist, name, arg)                                \
+  M_IF(M_GET_PROPERTY(oplist, LET_AS_INIT_WITH))(M_CALL_INIT_WITH, M_LETI_SINGLE5_INIT)(oplist, name, arg)
+#define M_LETI_SINGLE5_INIT(oplist, name, arg)                                \
+  M_IF(M_PARENTHESIS_P( arg ) )(M_CALL_INIT_WITH, M_CALL_INIT_SET)(oplist, name, M_REMOVE_PARENTHESIS (arg))
 
 
 /* Transform the va list by adding their number as the first argument of
@@ -3566,6 +3640,25 @@ m_core_parse2_enum (const char str[], const char **endptr)
   M_PAIR_2 d (M_PAIR_1 d, a)
 
 
+/* Initialize the container 'dest' as per 'oplist' INIT operator
+   and fill it with the given VA arguments with the _push_raw method
+   allowing INIT_WITH operator for the pushed argument.
+   NOTE: If the REVERSE operator exists, it assumes a list,
+   so it reverses the final order.
+*/
+#define M_INIT_WITH_VAI(oplist, dest, ...)                                    \
+  (void)(M_GET_INIT oplist (dest) ,                                           \
+         M_MAP2_C(M_INIT_WITH_VAI22_FUNC, (dest, oplist) , __VA_ARGS__)       \
+         M_IF_METHOD(REVERSE, oplist)(M_DEFERRED_COMMA M_GET_REVERSE oplist(dest), ) \
+         )
+
+#define M_INIT_WITH_VAI22_FUNC(pair, a)                                       \
+  M_INIT_WITH_VAI23_FUNC(M_PAIR_1 pair, M_PAIR_2 pair, a)
+
+#define M_INIT_WITH_VAI23_FUNC(d, op, a)                                      \
+  M_IF(M_PARENTHESIS_P( a ))(M_CALL_INIT_WITH, M_CALL_INIT_SET)(M_GET_OPLIST op, *M_C( M_GET_NAME op , _push_raw)(d), M_REMOVE_PARENTHESIS (a))
+
+
 /* Initialize the container 'dest' as per 'oplist' INIT operator
    and fill it with the given VA argument
    assumed to be pair (key,value) with the SET_KEY operator.
diff --git a/m-deque.h b/m-deque.h
index 493e2633..33a65748 100644
--- a/m-deque.h
+++ b/m-deque.h
@@ -264,6 +264,13 @@
     return ret;                                                               \
   }                                                                           \
                                                                               \
+  /* Internal, for INIT_WITH */                                               \
+  static inline type *                                                        \
+  M_C(name, _push_raw)(deque_t d)                                             \
+  {                                                                           \
+    return M_C(name, _push_back_raw)(d);                                      \
+  }                                                                           \
+                                                                              \
   static inline void                                                          \
   M_C(name, _push_back)(deque_t d, type const x)                              \
   {                                                                           \
@@ -982,7 +989,7 @@
 #define M_D3QU3_OPLIST_P3(name, oplist)                                       \
   (INIT(M_C(name, _init))                                                     \
    ,INIT_SET(M_C(name, _init_set))                                            \
-   ,INIT_WITH(API_1(M_INIT_VAI))                                              \
+   ,INIT_WITH(API_1(M_INIT_WITH_VAI))                                         \
    ,SET(M_C(name, _set))                                                      \
    ,CLEAR(M_C(name, _clear))                                                  \
    ,INIT_MOVE(M_C(name, _init_move))                                          \
diff --git a/m-funcobj.h b/m-funcobj.h
index ed252aa9..1ef096f4 100644
--- a/m-funcobj.h
+++ b/m-funcobj.h
@@ -131,6 +131,7 @@
   INIT_WITH(M_C(name, _init_with)),                                           \
   CLEAR(M_C(name, _clear)),                                                   \
   M_IF_METHOD_ALL(INIT, __VA_ARGS__)(INIT(M_C(name,_init)),),                 \
+  PROPERTIES(( LET_AS_INIT_WITH(1) ))                                         \
   )
 
 
diff --git a/m-list.h b/m-list.h
index ffb6fba6..838e939c 100644
--- a/m-list.h
+++ b/m-list.h
@@ -87,7 +87,7 @@
 #define M_L1ST_OPLIST_P3(name, oplist)                                        \
   (INIT(M_C(name, _init)),                                                    \
    INIT_SET(M_C(name, _init_set)),                                            \
-   INIT_WITH(API_1(M_INIT_VAI)),                                              \
+   INIT_WITH(API_1(M_INIT_WITH_VAI)),                                         \
    SET(M_C(name, _set)),                                                      \
    CLEAR(M_C(name, _clear)),                                                  \
    MOVE(M_C(name, _move)),                                                    \
@@ -990,6 +990,13 @@
     return ret;                                                               \
   }                                                                           \
                                                                               \
+  /* Internal, for INIT_WITH */                                               \
+  static inline type *                                                        \
+  M_C(name, _push_raw)(list_t d)                                              \
+  {                                                                           \
+    return M_C(name, _push_back_raw)(d);                                      \
+  }                                                                           \
+                                                                              \
   static inline void                                                          \
   M_C(name, _push_back)(list_t v, type const x)                               \
   {                                                                           \
diff --git a/m-serial-bin.h b/m-serial-bin.h
index 6aa98d17..0b77413d 100644
--- a/m-serial-bin.h
+++ b/m-serial-bin.h
@@ -345,7 +345,8 @@ static inline void m_serial_bin_write_clear(m_serial_write_t serial)
 /* Define a synonym of m_serial_read_t to the BIN serializer with its proper OPLIST */
 typedef m_serial_write_t m_serial_bin_write_t;
 #define M_OPL_m_serial_bin_write_t()                                          \
-  (INIT_WITH(m_serial_bin_write_init), CLEAR(m_serial_bin_write_clear), TYPE(m_serial_bin_write_t) )
+  (INIT_WITH(m_serial_bin_write_init), CLEAR(m_serial_bin_write_clear),       \
+  TYPE(m_serial_bin_write_t), PROPERTIES(( LET_AS_INIT_WITH(1) )) )
 
 
 /* Read from the stream 'serial' a boolean.
@@ -586,7 +587,8 @@ static inline void m_serial_bin_read_clear(m_serial_read_t serial)
 /* Define a synonym of m_serial_read_t to the BIN serializer with its proper OPLIST */
 typedef m_serial_read_t m_serial_bin_read_t;
 #define M_OPL_m_serial_bin_read_t()                                           \
-  (INIT_WITH(m_serial_bin_read_init), CLEAR(m_serial_bin_read_clear), TYPE(m_serial_bin_read_t) )
+  (INIT_WITH(m_serial_bin_read_init), CLEAR(m_serial_bin_read_clear),         \
+   TYPE(m_serial_bin_read_t), PROPERTIES(( LET_AS_INIT_WITH(1) )) )
 
 M_END_PROTECTED_CODE
 
diff --git a/m-serial-json.h b/m-serial-json.h
index 1cd5b8ad..114b6b81 100644
--- a/m-serial-json.h
+++ b/m-serial-json.h
@@ -277,7 +277,8 @@ static inline void m_serial_json_write_clear(m_serial_write_t serial)
 /* Define a synonym to the JSON serializer with a proper OPLIST */
 typedef m_serial_write_t m_serial_json_write_t;
 #define M_OPL_m_serial_json_write_t()                                         \
-  (INIT_WITH(m_serial_json_write_init), CLEAR(m_serial_json_write_clear), TYPE(m_serial_json_write_t) )
+  (INIT_WITH(m_serial_json_write_init), CLEAR(m_serial_json_write_clear),     \
+  TYPE(m_serial_json_write_t), PROPERTIES(( LET_AS_INIT_WITH(1) )) )
 
 
 
@@ -584,7 +585,8 @@ static inline void m_serial_json_read_clear(m_serial_read_t serial)
   to the JSON serializer with its proper OPLIST */
 typedef m_serial_read_t m_serial_json_read_t;
 #define M_OPL_m_serial_json_read_t()                                          \
-  (INIT_WITH(m_serial_json_read_init), CLEAR(m_serial_json_read_clear), TYPE(m_serial_json_read_t) )
+  (INIT_WITH(m_serial_json_read_init), CLEAR(m_serial_json_read_clear),       \
+  TYPE(m_serial_json_read_t) , PROPERTIES(( LET_AS_INIT_WITH(1) )) )
 
 
 
@@ -834,7 +836,8 @@ static inline void m_serial_str_json_write_clear(m_serial_write_t serial)
 /* Define a synonym to the JSON serializer with a proper OPLIST */
 typedef m_serial_write_t m_serial_str_json_write_t;
 #define M_OPL_m_serial_str_json_write_t()                                     \
-  (INIT_WITH(m_serial_str_json_write_init), CLEAR(m_serial_str_json_write_clear), TYPE(m_serial_str_json_write_t) )
+  (INIT_WITH(m_serial_str_json_write_init), CLEAR(m_serial_str_json_write_clear), \
+  TYPE(m_serial_str_json_write_t) , PROPERTIES(( LET_AS_INIT_WITH(1) )) )
 
 
 
@@ -1184,7 +1187,8 @@ static inline const char *m_serial_str_json_read_clear(m_serial_read_t serial)
   to the JSON serializer with its proper OPLIST */
 typedef m_serial_read_t m_serial_str_json_read_t;
 #define M_OPL_m_serial_str_json_read_t()                                      \
-  (INIT_WITH(m_serial_str_json_read_init), CLEAR(m_serial_str_json_read_clear), TYPE(m_serial_str_json_read_t) )
+  (INIT_WITH(m_serial_str_json_read_init), CLEAR(m_serial_str_json_read_clear), \
+  TYPE(m_serial_str_json_read_t), PROPERTIES(( LET_AS_INIT_WITH(1) )) )
 
 
 M_END_PROTECTED_CODE
diff --git a/m-string.h b/m-string.h
index 7d2dfd68..29c7733b 100644
--- a/m-string.h
+++ b/m-string.h
@@ -182,6 +182,7 @@ string_clear(string_t v)
 
 /* NOTE: Internaly used by STRING_DECL_INIT */
 static inline void m_str1ng_clear2(string_t *v) { string_clear(*v); }
+static inline string_ptr m_str1ng_init_ref(string_t v) { string_init(v); return v; }
 
 /* Clear the Dynamic string (destructor)
   and return a heap pointer to the string.
@@ -1735,7 +1736,7 @@ string_utf8_p(string_t str)
 #ifndef __cplusplus
 /* Initialize a constant string with the given C string */
 # define STRING_CTE(s)                                                        \
-  ((const string_t){{.u.heap = { .size = sizeof(s)-1, .alloc = sizeof(s) } ,  \
+  (string_srcptr)((const string_t){{.u.heap = { .size = sizeof(s)-1, .alloc = sizeof(s) } , \
         .ptr = ((struct { long long _n; char _d[sizeof (s)]; }){ 0, s })._d }})
 #else
 namespace m_lib {
@@ -1762,11 +1763,11 @@ namespace m_lib {
 
 /* Initialize and set a string to the given formatted value. */
 #define string_init_printf(v, ...)                                            \
-  (string_init (v),  string_printf (v, __VA_ARGS__) ) 
+  (string_printf ( m_str1ng_init_ref(v), __VA_ARGS__) )
 
 /* Initialize and set a string to the given formatted value. */
 #define string_init_vprintf(v, format, args)                                  \
-  (string_init (v),  string_vprintf (v, format, args) ) 
+  (string_vprintf ( m_str1ng_init_ref(v), format, args) )
 
 /* Initialize a string with the given list of arguments.
    Check if it is a formatted input or not by counting the number of arguments.
diff --git a/m-tuple.h b/m-tuple.h
index b0704da4..76288f92 100644
--- a/m-tuple.h
+++ b/m-tuple.h
@@ -208,7 +208,11 @@ namespace m_lib {
   typedef struct M_C(name, _s) *M_C(name, _ptr);                              \
   typedef const struct M_C(name, _s) *M_C(name, _srcptr);                     \
   /* Define internal type for oplist */                                       \
-  typedef name_t M_C(name, _ct);
+  typedef name_t M_C(name, _ct);                                              \
+  /* Save constant as the number of arguments (internal) */                   \
+  typedef enum {                                                              \
+    M_C3(m_tupl3_, name, _num_args) = M_NARGS(__VA_ARGS__)                    \
+  } M_C3(m_tupl3_, name, _num_args_ct);
 
 #define M_TUPL3_DEFINE_RECUR_TYPE_ELE(a)                                      \
   M_TUPL3_GET_TYPE a M_TUPL3_GET_FIELD a ;
@@ -305,9 +309,9 @@ namespace m_lib {
 
 /* Define the GET_AT_field & CGET_AT methods for all params. */
 #define M_TUPL3_DEFINE_GETTER_FIELD(name, ...)                                \
-  M_MAP2(M_TUPL3_DEFINE_GETTER_FIELD_PROTO, name, __VA_ARGS__)
+  M_MAP3(M_TUPL3_DEFINE_GETTER_FIELD_PROTO, name, __VA_ARGS__)
 
-#define M_TUPL3_DEFINE_GETTER_FIELD_PROTO(name, a)                            \
+#define M_TUPL3_DEFINE_GETTER_FIELD_PROTO(name, num, a)                       \
   static inline M_TUPL3_GET_TYPE a * M_C3(name, _get_at_, M_TUPL3_GET_FIELD a) \
        (M_C(name,_ct) my) {                                                   \
     M_TUPL3_CONTRACT(my);                                                     \
@@ -317,7 +321,12 @@ namespace m_lib {
     (M_C(name,_ct) const my) {                                                \
     M_TUPL3_CONTRACT(my);                                                     \
     return &(my->M_TUPL3_GET_FIELD a);                                        \
-  }
+  }                                                                           \
+  /* Same but uses numerical index for accessing the field (internal) */      \
+  static inline M_TUPL3_GET_TYPE a * M_C4(m_tupl3_, name, _get_at_, num)      \
+       (M_C(name,_ct) my) {                                                   \
+    return &(my->M_TUPL3_GET_FIELD a);                                        \
+  }                                                                           \
 
 
 /* Define the SET_field methods for all params. */
@@ -623,6 +632,51 @@ namespace m_lib {
   M_TUPL3_CALL_CLEAN(a, el1 -> M_TUPL3_GET_FIELD a);
 
 
+/* INIT_WITH macro enabling recursive INIT_WITH initialization
+    tuple = { int, string_t, array<string_t> }
+  USAGE:
+    M_LET( (x, 2, ("John"), ( ("Bear"), ("Rabbit") )), tuple_t)
+
+  "If you think it's simple, you're deluding yourself."
+
+  Several pass are done:
+  1) If the number of arguments doesn't match the number of oplists of the 
+  tuple oplist, it is assumed something is wrong. It uses the _init_emplace
+  function to provide proper warning in such case.
+  2) Otherwise, it checks that the number of arguments matches the number
+  of arguments of the tuple definition.
+  3) Mix all arguments with their associated oplists to have pair (arg, oplist),
+  4) Map the following macro for each computed pair :
+  4.a) If INIT_WITH macro is not defined for this pair, it uses INIT_SET
+  4.b) If the argument is encapsulated with parenthesis, it uses INIT_WITH
+  4.c) If the oplist property LET_AS_INIT_WITH is defined, it uses INIT_WITH
+  4.d) Otherwise it uses INIT_SET.
+*/
+#define M_TUPL3_INIT_WITH(oplist, dest, ...)                                  \
+  M_TUPL3_INIT_WITH_P1(M_GET_NAME oplist, M_GET_OPLIST oplist, dest, __VA_ARGS__)
+#define M_TUPL3_INIT_WITH_P1(name, oplist_arglist, dest, ...)                 \
+  M_IF(M_NOTEQUAL( M_NARGS oplist_arglist, M_NARGS (__VA_ARGS__)))            \
+    (M_TUPL3_INIT_WITH_P1_FUNC, M_TUPL3_INIT_WITH_P1_MACRO)(name, oplist_arglist, dest, __VA_ARGS__)
+#define M_TUPL3_INIT_WITH_P1_FUNC(name, oplist_arglist, dest, ...)            \
+  M_C(name, _init_emplace)(dest, __VA_ARGS__)
+#define M_TUPL3_INIT_WITH_P1_MACRO(name, oplist_arglist, dest, ...)           \
+  ( M_STATIC_ASSERT( M_NARGS oplist_arglist == M_C3(m_tupl3_, name, _num_args), M_LIB_DIMENSION_ERROR, "The number of oplists given to TUPLE_OPLIST don't match the number of oplists used to create the tuple." ), \
+    M_STATIC_ASSERT( M_NARGS(__VA_ARGS__) == M_C3(m_tupl3_, name, _num_args), M_LIB_DIMENSION_ERROR, "Missing / Too many arguments for tuple"), \
+    M_MAP3(M_TUPL3_INIT_WITH_P2, (name, dest), M_OPFLAT M_MERGE_ARGLIST( oplist_arglist, (__VA_ARGS__) ) ) \
+    (void) 0)
+#define M_TUPL3_INIT_WITH_P2(name_dest, num, pair)                            \
+    M_TUPL3_INIT_WITH_P3( M_PAIR_1 name_dest, M_PAIR_2 name_dest, num, M_PAIR_1 pair, M_PAIR_2 pair )
+#define M_TUPL3_INIT_WITH_P3(name, dest, num, oplist, param)                  \
+  M_IF(M_TEST_METHOD_P(INIT_WITH, oplist))(M_TUPL3_INIT_WITH_P4, M_TUPL3_INIT_WITH_SET)(name, dest, num, oplist, param)
+#define M_TUPL3_INIT_WITH_SET(name, dest, num, oplist, param)                 \
+  M_CALL_INIT_SET (oplist, *M_C4(m_tupl3_, name, _get_at_, num)(dest), param) ,
+#define M_TUPL3_INIT_WITH_P4(name, dest, num, oplist, param)                  \
+  M_IF(M_PARENTHESIS_P( param))(M_TUPL3_INIT_WITH_P5, M_TUPL3_INIT_WITH_P6)(name, dest, num, oplist, param)
+#define M_TUPL3_INIT_WITH_P5(name, dest, num, oplist, param)                  \
+  M_CALL_INIT_WITH(oplist, *M_C4(m_tupl3_, name, _get_at_, num)(dest), M_REMOVE_PARENTHESIS (param) ) ,
+#define M_TUPL3_INIT_WITH_P6(name, dest, num, oplist, param)                  \
+  M_IF(M_GET_PROPERTY(oplist, LET_AS_INIT_WITH))(M_TUPL3_INIT_WITH_P5, M_TUPL3_INIT_WITH_SET)(name, dest, num, oplist, param)
+
 /* Macros for testing for the presence of a method in the parameter (name, type, oplist) */
 #define M_TUPL3_TEST_METHOD_P(method, trio)                                   \
   M_APPLY(M_TUPL3_TEST_METHOD2_P, method, M_OPFLAT trio)
@@ -650,11 +704,12 @@ namespace m_lib {
 #define M_TUPL3_OPLIST_P3(name, ...)                                          \
   (M_IF_METHOD_ALL(INIT, __VA_ARGS__)(INIT(M_C(name,_init)),),                \
    INIT_SET(M_C(name, _init_set)),                                            \
-   INIT_WITH(M_C(name, _init_emplace)),                                       \
+   INIT_WITH(API_1(M_TUPL3_INIT_WITH)),                                       \
    SET(M_C(name,_set)),                                                       \
    CLEAR(M_C(name, _clear)),                                                  \
    NAME(name),                                                                \
    TYPE(M_C(name,_ct)),                                                       \
+   OPLIST( (__VA_ARGS__) ),                                                   \
    M_IF_METHOD_ALL(CMP, __VA_ARGS__)(CMP(M_C(name, _cmp)),),                  \
    M_IF_METHOD_ALL(HASH, __VA_ARGS__)(HASH(M_C(name, _hash)),),               \
    M_IF_METHOD_ALL(EQUAL, __VA_ARGS__)(EQUAL(M_C(name, _equal_p)),),          \
diff --git a/tests/test-malgo.c b/tests/test-malgo.c
index 63e05295..44a96c58 100644
--- a/tests/test-malgo.c
+++ b/tests/test-malgo.c
@@ -239,7 +239,7 @@ static void test_list(void)
     assert(list_int_equal_p (l1, l3));
   }
 
-  M_LET( (l1, 4, 28, 29, 31, 34), (l2, 1, 3, 31, 32, 33), (l3, 31), LIST_OPLIST(list_int, M_DEFAULT_OPLIST)) {
+  M_LET( (l1, 4, 28, 29, 31, 34), (l2, 1, 3, 31, 32, 33), (l3, (31)), LIST_OPLIST(list_int, M_DEFAULT_OPLIST)) {
     algo_list_sort_intersect(l1, l2);
     assert(list_int_equal_p (l1, l3));
   }
@@ -618,7 +618,7 @@ static void test_insert(void)
 
 static void test_string_utf8(void)
 {
-  M_LET( (s, "H€llo René Chaînôr¬"), string_t)
+  M_LET( (s, ("H€llo René Chaînôr¬") ), string_t)
     M_LET( (ref, 72, 8364, 108, 108, 111, 32, 82, 101, 110, 233, 32, 67, 104, 97, 238, 110, 244, 114, 172), a, array_uint_t) {
     // Convert the string into an array of unicode.
     ALGO_EXTRACT(a, array_uint_t, s, string_t);
diff --git a/tests/test-mcore.c b/tests/test-mcore.c
index efda592d..5b89b8a9 100644
--- a/tests/test-mcore.c
+++ b/tests/test-mcore.c
@@ -248,13 +248,13 @@ static void test_let(void)
     M_LET((zz,z), M_CLASSIC_OPLIST(testobj)) {
       assert( testobj_cmp_ui(zz, 12) == 0);
     }
-    M_LET((zz,42), M_OPEXTEND(M_CLASSIC_OPLIST(testobj), INIT_WITH(testobj_init_set_ui))) {
+    M_LET((zz,(42)), M_OPEXTEND(M_CLASSIC_OPLIST(testobj), INIT_WITH(testobj_init_set_ui))) {
       assert( testobj_cmp_ui(zz, 42) == 0);
     }
     M_LET((zz,z), z2, M_CLASSIC_OPLIST(testobj)) {
       assert( testobj_cmp_ui(zz, 12) == 0);
     }
-    M_LET(z3, (zz,42), M_OPEXTEND(M_CLASSIC_OPLIST(testobj), INIT_WITH(testobj_init_set_ui))) {
+    M_LET(z3, (zz,(42)), M_OPEXTEND(M_CLASSIC_OPLIST(testobj), INIT_WITH(testobj_init_set_ui))) {
       assert( testobj_cmp_ui(zz, 42) == 0);
     }
     b = true;
@@ -263,6 +263,33 @@ static void test_let(void)
   }
   assert(b);
 
+  // Test of recursive INIT_WITH within M_LET
+#define OPL1 (TYPE(int), INIT_WITH(OPL1_F))
+#define OPL1_F(d, x) ((d) = (x))
+#define OPL2 (TYPE(int), INIT_WITH(API_1(OPL2_F)), OPLIST(OPL1) )
+#define OPL2_F(opl, d, x) M_APPLY_API(M_GET_INIT_WITH M_GET_OPLIST opl, M_GET_OPLIST opl, d, x)
+#define OPL3 (TYPE(int), INIT_WITH(API_1(OPL3_F)), OPLIST(OPL2) )
+#define OPL3_F(opl, d, x) M_APPLY_API(M_GET_INIT_WITH M_GET_OPLIST opl, M_GET_OPLIST opl, d, x)
+#define OPL4 (TYPE(int), INIT_WITH(API_1(OPL4_F)), OPLIST(OPL3) )
+#define OPL4_F(opl, d, x) M_APPLY_API(M_GET_INIT_WITH M_GET_OPLIST opl, M_GET_OPLIST opl, d, x)
+#define OPL5 (TYPE(int), INIT_WITH(API_1(OPL5_F)), OPLIST(OPL4) )
+#define OPL5_F(opl, d, x) M_APPLY_API(M_GET_INIT_WITH M_GET_OPLIST opl, M_GET_OPLIST opl, d, x)
+#define OPL6 (TYPE(int), INIT_WITH(API_1(OPL6_F)), OPLIST(OPL5) )
+#define OPL6_F(opl, d, x) M_APPLY_API(M_GET_INIT_WITH M_GET_OPLIST opl, M_GET_OPLIST opl, d, x)
+  
+  M_LET( (x, 4585) , OPL1)
+    assert (x == 4585);
+  M_LET( (x, 4586) , OPL2)
+    assert (x == 4586);
+  M_LET( (x, 4587) , OPL3)
+    assert (x == 4587);
+  M_LET( (x, 4588) , OPL4)
+    assert (x == 4588);
+  M_LET( (x, 4589) , OPL5)
+    assert (x == 4589);
+  M_LET( (x, 4590) , OPL6)
+    assert (x == 4590);
+    
   int c = 0;
   M_LET_IF( assert(c++ == 0), (assert(c++ == 1), true), assert(c++ == 3)) {
     assert(c++ == 2);
@@ -726,10 +753,10 @@ static void test_M_CSTR(void)
 static void test_properties(void)
 {
 #define OP_PROP() ( INIT(init), PROPERTIES((INIT(1), IT_TYPE(2), INIT_WITH(priority))) )
-  assert( M_GET_OPPROPERTY (OP_PROP(), INIT ) == 1);
-  assert( M_GET_OPPROPERTY (OP_PROP(), CLEAR ) == 0);
-  assert( M_GET_OPPROPERTY (OP_PROP(), IT_TYPE ) == 2);
-  assert( M_KEYWORD_P( M_GET_OPPROPERTY (OP_PROP(), INIT_WITH ), priority));
+  assert( M_GET_PROPERTY (OP_PROP(), INIT ) == 1);
+  assert( M_GET_PROPERTY (OP_PROP(), CLEAR ) == 0);
+  assert( M_GET_PROPERTY (OP_PROP(), IT_TYPE ) == 2);
+  assert( M_KEYWORD_P( M_GET_PROPERTY (OP_PROP(), INIT_WITH ), priority));
 }
 int main(void)
 {
diff --git a/tests/test-mlist.c b/tests/test-mlist.c
index 216adb10..39f24c8c 100644
--- a/tests/test-mlist.c
+++ b/tests/test-mlist.c
@@ -39,6 +39,8 @@ LIST_DUAL_PUSH_DEF(list2_mpz, testobj_t, TESTOBJ_OPLIST)
 LIST_DEF(list_min_z, testobj_t, (INIT_SET(testobj_init_set), SET(testobj_set), CLEAR(testobj_clear)))
 LIST_DUAL_PUSH_DEF(list2_min_z, testobj_t, (INIT_SET(testobj_init_set), SET(testobj_set), CLEAR(testobj_clear)))
 
+LIST_DEF(list_string, string_t)
+#define M_OPL_list_string_t() LIST_OPLIST(list_string, STRING_OPLIST)
 
 LIST_DEF_AS(list_double, ListDouble, ListDoubleIt, double)
 #define M_OPL_ListDouble() LIST_OPLIST(list_double, M_DEFAULT_OPLIST)
@@ -674,6 +676,31 @@ static void test_double(void)
   }
 }
 
+static void test_let_string(void)
+{
+  M_LET( (y, ("!") ), string_t)                   // string_t y = string_t{"!"}
+    M_LET( (z, y), string_t)                      // string_t z = y
+    M_LET( (x, ("Hello"), ("%d World", 2), y ), list_string_t) // astr_t x = { string_t{"Hello"}, string_t{"World"}, z }
+    M_LET( (xx, x), list_string_t)                // astr_t xx = x
+    M_LET( (zz, (("Hellno")) ), list_string_t)     // astr_t zz = { string_t{"Hellno"} }
+    M_LET( (zx, (y) ), list_string_t)             // astr_t zx = { z }
+    M_LET( (tab_name, STRING_CTE("My"), STRING_CTE("CD"), STRING_CTE("IS"), STRING_CTE("OUT")), list_string_t)
+    {
+      assert(string_equal_str_p( y, "!"));
+      assert(string_equal_str_p( z, "!"));
+      list_string_get_str(y, x, false);
+      assert(string_equal_str_p(y, "[\"Hello\",\"2 World\",\"!\"]"));
+      list_string_get_str(y, xx, false);
+      assert(string_equal_str_p(y, "[\"Hello\",\"2 World\",\"!\"]"));
+      list_string_get_str(y, zz, false);
+      assert(string_equal_str_p(y, "[\"Hellno\"]"));
+      list_string_get_str(y, zx, false);
+      assert(string_equal_str_p(y, "[\"!\"]"));
+      list_string_get_str(y, tab_name, false);
+      assert(string_equal_str_p(y, "[\"My\",\"CD\",\"IS\",\"OUT\"]"));
+    }
+}
+
 int main(void)
 {
   test_uint();
@@ -682,6 +709,7 @@ int main(void)
   test_dual_it1();
   test_out_default_oplist();
   test_double();
+  test_let_string();
   exit(0);
 }
 
diff --git a/tests/test-mstring.c b/tests/test-mstring.c
index 96d8bdf4..5c9a6a07 100644
--- a/tests/test-mstring.c
+++ b/tests/test-mstring.c
@@ -728,7 +728,7 @@ static void test_bounded_M_LET(void)
     assert (string16_empty_p(x));
   }
   
-  M_LET( (x,"tree"), BOUNDED_STRING_OPLIST(string16)) {
+  M_LET( (x, ("tree")), BOUNDED_STRING_OPLIST(string16)) {
     assert (string16_equal_str_p(x, "tree"));
   }
 
@@ -753,7 +753,7 @@ static void test_M_LET(void)
     string_set(s2, s1);
     assert(string_equal_p(s1, s2));
   }
-  M_LET((s1,"OK"),string_t) {
+  M_LET((s1,("OK")),string_t) {
     assert(string_equal_str_p(s1, "OK"));
   }
   M_LET((s1,"OK S=%d", 16),string_t) {
@@ -764,10 +764,9 @@ static void test_M_LET(void)
     assert(string_empty_p(s2));
     assert(string_equal_str_p(s3, "42-17"));
   }
-  M_LET( (s1, "Hello"), string_t) {
+  M_LET( (s1, ("Hello")), string_t) {
     assert(string_equal_str_p(s1, "Hello"));
 #if (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L)
-    // Initalization with another string is only supported in C11 mode.
     M_LET( (s2, s1), string_t) {
       // In C11 mode, string_equal_p accept also C string
       assert(string_equal_p(s2, "Hello"));
diff --git a/tests/test-mtuple.c b/tests/test-mtuple.c
index 0ac95441..67d6169b 100644
--- a/tests/test-mtuple.c
+++ b/tests/test-mtuple.c
@@ -118,6 +118,48 @@ static void check_clean(void)
     rtuple_clean(r);
     assert(string_equal_str_p (r->name, ""));    
   }
+  
+  M_LET( (r, ("Hello"), 4), TUPLE_OPLIST(pair2_str, STRING_OPLIST, M_DEFAULT_OPLIST) )  {
+    assert(string_equal_str_p (r->str, "Hello"));
+    assert(r->value == 4);
+    pair2_str_clean(r);
+    assert(string_equal_str_p (r->str, ""));
+  }
+
+  M_LET( (s, ("Goldy") ), STRING_OPLIST) 
+  M_LET( (r, s, 46), TUPLE_OPLIST(pair2_str, STRING_OPLIST, M_DEFAULT_OPLIST) )
+  M_LET( (q, r), TUPLE_OPLIST(pair2_str, STRING_OPLIST, M_DEFAULT_OPLIST) ) {
+    assert(string_equal_str_p (q->str, "Goldy"));
+    assert(q->value == 46);
+    pair2_str_clean(q);
+    assert(string_equal_str_p (q->str, ""));
+  }
+
+  // Wrong oplist usage: fall back to _init_emplace.
+  M_LET( (s, ("Goldy McDuck") ), STRING_OPLIST) 
+  M_LET((r, s, 460), TUPLE_OPLIST(pair2_str, STRING_OPLIST) )  {
+    assert(string_equal_str_p (r->str, "Goldy McDuck"));
+    assert(r->value == 460);
+    pair2_str_clean(r);
+    assert(string_equal_str_p (r->str, ""));
+  }
+
+  // Two level of parenthesis needed: 
+  //  one to perform an emplace with INIT_WITH for the tuple
+  //  another level to emplace the string_t
+  M_LET( (r, (("Two emplace"))), TUPLE_OPLIST(single_str, STRING_OPLIST) ) {
+    assert(string_equal_str_p (r->vala, "Two emplace"));
+    single_str_clean(r);
+    assert(string_equal_str_p (r->vala, ""));
+  }
+
+  M_LET( (s, ("Goldy McDuck") ), STRING_OPLIST) 
+  M_LET( (r, (s)), TUPLE_OPLIST(single_str, STRING_OPLIST) ) {
+    assert(string_equal_str_p (r->vala, "Goldy McDuck"));
+    single_str_clean(r);
+    assert(string_equal_str_p (r->vala, ""));
+  }
+
 }
 
 static void check_io(void)