diff --git a/octa/string.h b/octa/string.h
index a1b9d97..05e254e 100644
--- a/octa/string.h
+++ b/octa/string.h
@@ -123,6 +123,19 @@ namespace octa {
     };
 
     typedef StringBase<char> String;
+
+    template<typename R>
+    String concat(R range, String sep = " ") {
+        String ret;
+        if (range.empty()) return move(ret);
+        for (;;) {
+            ret += range.first();
+            range.pop_first();
+            if (range.empty()) break;
+            ret += sep;
+        }
+        return move(ret);
+    }
 }
 
 #endif
\ No newline at end of file
diff --git a/octa/vector.h b/octa/vector.h
index aa62aac..6d18d3f 100644
--- a/octa/vector.h
+++ b/octa/vector.h
@@ -72,7 +72,7 @@ namespace octa {
         Vector(): p_buf(nullptr), p_len(0), p_cap(0) {}
 
         explicit Vector(size_t n, const T &val = T()): Vector() {
-            p_buf = new uchar[n * sizeof(T)];
+            p_buf = (T *)new uchar[n * sizeof(T)];
             p_len = p_cap = n;
             T *cur = p_buf, *last = p_buf + n;
             while (cur != last) new (cur++) T(val);