diff --git a/src/main.cpp b/src/main.cpp
index c1fb578..f9cfe84 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -41,6 +41,7 @@ std::ostream& help(std::ostream& out) {
     << "option:\n"
     << "   -h,   --help     | get help.\n"
     << "   -v,   --version  | get version.\n"
+    << "   -r,   --repl     | use repl interpreter(experimental).\n"
     << "\nnasal [option] <file> [argv]\n"
     << "option:\n"
     << "   -a,   --ast      | view ast after link/optimize process.\n"
@@ -54,7 +55,6 @@ std::ostream& help(std::ostream& out) {
     << "         --prof     | show profiling result, available under debug mode.\n"
     << "         --prof-all | show profiling result of all files,"
     << "available under debug mode.\n"
-    << "   -r,   --repl     | use repl interpreter(experimental).\n"
     << "file:\n"
     << "   <filename>       | execute file.\n"
     << "argv:\n"
diff --git a/test/calc.nas b/test/calc.nas
index f1de5ac..440701e 100644
--- a/test/calc.nas
+++ b/test/calc.nas
@@ -49,7 +49,7 @@ var count=func(s,c){
 }
 
 var column=func(number){
-    number=number>=1000?substr(str(number/1000),0,3)~'k':str(number);
+    number=number>=1000?substr(str(number/1000),0,4)~'k':str(number);
     return padding.leftpad(number,6);
 }
 
diff --git a/test/datalog.nas b/test/datalog.nas
index 4530a24..6757856 100644
--- a/test/datalog.nas
+++ b/test/datalog.nas
@@ -159,4 +159,46 @@ for(var i=10;i<1e6;i*=10) {
 println("cartesian");
 for(var i=100;i<600;i+=100) {
     cartesian(i);
+}
+
+var person_data = [];
+var person = func(name, age) {
+    append(person_data, [name, age]);
+    return person_data;
+}
+
+var know_data = [];
+var know = func(name_a, name_b) {
+    append(know_data, [name_a, name_b]);
+}
+
+person("a", 1);
+person("b", 2);
+person("c", 3);
+person("d", 4);
+
+know("a", "b");
+know("b", "c");
+know("c", "d");
+know("d", "a");
+
+# maybe_know(a, b) :- know(a, tmp), know(tmp, b).
+var maybe_know_data = [];
+
+var temp = [];
+
+foreach(var i; know_data) {
+    foreach(var j; know_data) {
+        append(temp, [i[0], i[1], j[0], j[1]]);
+    }
+}
+
+foreach(var i; temp) {
+    if (!cmp(i[1], i[2])) {
+        append(maybe_know_data, [i, i[0], i[3]]);
+    }
+}
+
+foreach(var res; maybe_know_data) {
+    println(res[0], " -> ", res[1], " ", res[2]);
 }
\ No newline at end of file