diff --git a/bin/main.cpp b/bin/main.cpp
index 7ac9f66..b77dcc3 100644
--- a/bin/main.cpp
+++ b/bin/main.cpp
@@ -14,11 +14,11 @@ int main(int argc, char *argv[])
   {// ex: split_str
     std::string str { "asdf,qwer,zxcv" };
     hack::string::v_str v = hack::string::split_str(str, ',');
-    for (const auto& c : v) std::cout << c << std::endl;
+    for (const auto& c : v) hack::log()(c);
   }
 
   {// ex: within
-    std::cout << std::boolalpha << hack::range::within(12, 34, 12, 23, 31, 17, 22, 33) << std::endl;
+    hack::log()(hack::range::within(12, 34, 12, 23, 31, 17, 22, 33));
   }
 
   {// ex: vector_multiset
@@ -43,7 +43,7 @@ int main(int argc, char *argv[])
 
     std::vector<std::string> vs { "asdf", "qwer", "zxcv" };
     hack::log()("vector", vs, 1, 2, 'a');
-    
+  
     std::list<std::string> ls {  "asdf", "qwer", "zxcv" };
     hack::log()(vs, ls);
 
@@ -58,7 +58,7 @@ int main(int argc, char *argv[])
     std::vector<int> v { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
     hack::log()(hack::container::matches(v, 2, 5, 4, 12));
   }
-  
+
   {// ex: vector_remove_at
     std::vector<int> v { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
     hack::container::vector_remove_at(v, 3);
diff --git a/src/logger/logger.hpp b/src/logger/logger.hpp
index d6755f2..ec44a3d 100644
--- a/src/logger/logger.hpp
+++ b/src/logger/logger.hpp
@@ -9,23 +9,6 @@
 
 namespace hack
 {
-  template<typename T>
-  concept is_sequence_container = std::same_as<T, std::vector<typename T::value_type>> || 
-    std::same_as<T, std::list<typename T::value_type>>;
-
-  template<typename T>
-  concept is_tuple = requires (T t)
-  { 
-    std::tuple_cat(t, std::make_tuple(1, "tuple"));
-  };
-
-  template<class T>
-  concept is_string = std::is_convertible_v<T, std::string_view>;
-
-  template<class T>
-  concept is_map = std::same_as<T, std::map<typename T::key_type, typename T::mapped_type, typename T::key_compare, typename T::allocator_type>> ||
-    std::same_as<T, std::unordered_map<typename T::key_type, typename T::mapped_type, typename T::hasher, typename T::key_equal, typename T::allocator_type>>;
-
   class log
   {
     public:
@@ -67,7 +50,7 @@ namespace hack
         print(args...);
       }
 
-      template<is_string T>
+      template<concepts::is_string T>
       static void print_t(const T& data)
       {
         std::cout << data << (count != 0 ? devider : "");
@@ -79,7 +62,7 @@ namespace hack
         std::cout << data << (count != 0 ? devider : "");
       }
 
-      template<is_sequence_container T>
+      template<concepts::is_sequence_container T>
       static void print_t(const T& data)
       {
         std::cout << "{ ";
@@ -87,7 +70,7 @@ namespace hack
         std::cout << " }" << (count != 0 ? devider : "");
       }
 
-      template<is_map T>
+      template<concepts::is_map T>
       static void print_t(const T& data)
       {
         std::cout << "{";
@@ -95,7 +78,7 @@ namespace hack
         std::cout << "}" << (count != 0 ? devider : "");
       }
 
-      template<is_tuple T, typename std::size_t... idx>
+      template<concepts::is_tuple T, typename std::size_t... idx>
       static void print_t(const T& data)
       {
         print_t(data, std::make_index_sequence<std::tuple_size<T>::value>{});