diff --git a/examples/quick_sort.v b/examples/quick_sort.v
index fd37a2ce20..69c1675208 100644
--- a/examples/quick_sort.v
+++ b/examples/quick_sort.v
@@ -11,12 +11,12 @@ fn main() {
 		arr << rand.intn(gen_max)
 	}
 	println('length of random array is $arr.len')
-	println('before quick sort whether array is sorted: ${is_sorted(arr)}')
-	quick_sort(mut arr, 0, arr.len-1)
-	println('after quick sort whether array is sorted: ${is_sorted(arr)}')
+	println('before quick sort whether array is sorted: ${is_sorted<int>(arr)}')
+	quick_sort<int>(mut arr, 0, arr.len-1)
+	println('after quick sort whether array is sorted: ${is_sorted<int>(arr)}')
 }
 
-fn quick_sort(mut arr []int, l int, r int) {
+fn quick_sort<T>(mut arr []T, l int, r int) {
 	if l>=r { return }
 	mut sep := l  // what is sep: [...all_value<arr[sep]...sep...all_value>=arr[sep]...]
 	for i in l+1..r+1 {
@@ -26,11 +26,11 @@ fn quick_sort(mut arr []int, l int, r int) {
 		}
 	}
 	arr[l], arr[sep] = arr[sep], arr[l]
-	quick_sort(mut arr, l, sep-1)
-	quick_sort(mut arr, sep+1, r)
+	quick_sort<T>(mut arr, l, sep-1)
+	quick_sort<T>(mut arr, sep+1, r)
 }
 
-fn is_sorted(arr []int) bool {
+fn is_sorted<T>(arr []T) bool {
 	for i in 0..arr.len-1 {
 		if arr[i] > arr[i+1] {
 			return false