diff --git a/CMakeLists.txt b/CMakeLists.txt
index 66040d0e..3f2a71f7 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -164,7 +164,7 @@ set(INCLUDE
         include/tcframe/util.hpp
         include/tcframe/util/StringUtils.hpp
         include/tcframe/util/optional.hpp
-        include/tcframe/validator/number.hpp
+        include/tcframe/validator/core.hpp
         include/tcframe/validator/vector.hpp
 )
 
@@ -260,7 +260,7 @@ set(TEST_UNIT
         test/unit/tcframe/util/OptionalTests.cpp
         test/unit/tcframe/util/StringUtilsTests.cpp
         test/unit/tcframe/util/TestUtils.hpp
-        test/unit/tcframe/validator/NumberValidatorTests.cpp
+        test/unit/tcframe/validator/CoreValidatorTests.cpp
         test/unit/tcframe/validator/VectorValidatorTests.cpp
 )
 
diff --git a/include/tcframe/spec.hpp b/include/tcframe/spec.hpp
index 63be5740..27dc9b4e 100644
--- a/include/tcframe/spec.hpp
+++ b/include/tcframe/spec.hpp
@@ -7,4 +7,4 @@
 #include "tcframe/spec/testcase.hpp"
 #include "tcframe/spec/variable.hpp"
 #include "tcframe/spec/verifier.hpp"
-
+#include "tcframe/validator/core.hpp"
diff --git a/include/tcframe/validator/core.hpp b/include/tcframe/validator/core.hpp
new file mode 100644
index 00000000..d6d53526
--- /dev/null
+++ b/include/tcframe/validator/core.hpp
@@ -0,0 +1,32 @@
+
+#include <string>
+#include <type_traits>
+#include <vector>
+
+using std::enable_if_t;
+using std::is_arithmetic_v;
+
+namespace tcframe {
+
+template<typename T>
+using ValueType = enable_if_t<is_arithmetic_v<T>>;
+
+template<typename T, typename = ValueType<T>>
+struct ValueValidator {
+private:
+    T val;
+
+public:
+    explicit ValueValidator(T _val) : val(_val) {}
+
+    bool isBetween(T minVal, T maxVal) {
+        return minVal <= val && val <= maxVal;
+    }
+};
+
+template<typename T, typename = ValueType<T>>
+ValueValidator<T> valueOf(T val) {
+    return ValueValidator(val);
+}
+
+}
diff --git a/include/tcframe/validator/number.hpp b/include/tcframe/validator/number.hpp
deleted file mode 100644
index f26f7fa4..00000000
--- a/include/tcframe/validator/number.hpp
+++ /dev/null
@@ -1,8 +0,0 @@
-namespace tcframe {
-
-template<typename T>
-bool isBetween(T N, T mn, T mx) {
-    return N >= mn && N <= mx;
-}
-
-}
diff --git a/test/ete/resources/interactive/spec.cpp b/test/ete/resources/interactive/spec.cpp
index b77061b5..24fc870c 100644
--- a/test/ete/resources/interactive/spec.cpp
+++ b/test/ete/resources/interactive/spec.cpp
@@ -20,7 +20,7 @@ class ProblemSpec : public BaseProblemSpec {
     }
 
     void Constraints() {
-        CONS(1 <= N && N <= 10);
+        CONS(valueOf(N).isBetween(1, 10));
     }
 };
 
diff --git a/test/ete/resources/multi-no-output/spec.cpp b/test/ete/resources/multi-no-output/spec.cpp
index 4ba5cf99..90f77a25 100644
--- a/test/ete/resources/multi-no-output/spec.cpp
+++ b/test/ete/resources/multi-no-output/spec.cpp
@@ -26,12 +26,12 @@ class ProblemSpec : public BaseProblemSpec {
     }
 
     void MultipleTestCasesConstraints() {
-        CONS(1 <= T && T <= 5);
+        CONS(valueOf(T).isBetween(1, 5));
     }
 
     void Constraints() {
-        CONS(1 <= A && A <= 100);
-        CONS(1 <= B && B <= 100);
+        CONS(valueOf(A).isBetween(1, 100));
+        CONS(valueOf(B).isBetween(1, 100));
     }
 };
 
diff --git a/test/ete/resources/multi-prefix/spec.cpp b/test/ete/resources/multi-prefix/spec.cpp
index 00a4ba76..3f51fa9d 100644
--- a/test/ete/resources/multi-prefix/spec.cpp
+++ b/test/ete/resources/multi-prefix/spec.cpp
@@ -27,12 +27,12 @@ class ProblemSpec : public BaseProblemSpec {
     }
 
     void MultipleTestCasesConstraints() {
-        CONS(1 <= T && T <= 5);
+        CONS(valueOf(T).isBetween(1, 5));
     }
 
     void Constraints() {
-        CONS(1 <= A && A <= 100);
-        CONS(1 <= B && B <= 100);
+        CONS(valueOf(A).isBetween(1, 100));
+        CONS(valueOf(B).isBetween(1, 100));
     }
 };
 
diff --git a/test/ete/resources/multi/spec.cpp b/test/ete/resources/multi/spec.cpp
index bf4af81a..af3b567d 100644
--- a/test/ete/resources/multi/spec.cpp
+++ b/test/ete/resources/multi/spec.cpp
@@ -30,8 +30,8 @@ class ProblemSpec : public BaseProblemSpec {
     }
 
     void Constraints() {
-        CONS(1 <= A && A <= 100);
-        CONS(1 <= B && B <= 100);
+        CONS(valueOf(A).isBetween(1, 100));
+        CONS(valueOf(B).isBetween(1, 100));
     }
 };
 
diff --git a/test/ete/resources/normal-complex-formats/spec.cpp b/test/ete/resources/normal-complex-formats/spec.cpp
index f98c7675..f913a1d4 100644
--- a/test/ete/resources/normal-complex-formats/spec.cpp
+++ b/test/ete/resources/normal-complex-formats/spec.cpp
@@ -39,7 +39,7 @@ class ProblemSpec : public BaseProblemSpec {
     }
 
     void Constraints() {
-        CONS(1 <= N && N <= 10);
+        CONS(valueOf(N).isBetween(1, 10));
     }
 };
 
diff --git a/test/ete/resources/normal-custom-scorer/spec.cpp b/test/ete/resources/normal-custom-scorer/spec.cpp
index 538ce35b..5a61f502 100644
--- a/test/ete/resources/normal-custom-scorer/spec.cpp
+++ b/test/ete/resources/normal-custom-scorer/spec.cpp
@@ -21,8 +21,8 @@ class ProblemSpec : public BaseProblemSpec {
     }
 
     void Constraints() {
-        CONS(1 <= A && A <= 10);
-        CONS(1 <= B && B <= 10);
+        CONS(valueOf(A).isBetween(1, 10));
+        CONS(valueOf(B).isBetween(1, 10));
     }
 };
 
diff --git a/test/ete/resources/normal-lifecycle/spec.cpp b/test/ete/resources/normal-lifecycle/spec.cpp
index c5526592..55a3e48c 100644
--- a/test/ete/resources/normal-lifecycle/spec.cpp
+++ b/test/ete/resources/normal-lifecycle/spec.cpp
@@ -31,7 +31,7 @@ class ProblemSpec : public BaseProblemSpec {
     }
 
     void Constraints() {
-        CONS(1 <= N && N <= 10);
+        CONS(valueOf(N).isBetween(1, 10));
     }
 };
 
diff --git a/test/ete/resources/normal-no-output/spec.cpp b/test/ete/resources/normal-no-output/spec.cpp
index aed13700..90601a3f 100644
--- a/test/ete/resources/normal-no-output/spec.cpp
+++ b/test/ete/resources/normal-no-output/spec.cpp
@@ -21,8 +21,8 @@ class ProblemSpec : public BaseProblemSpec {
     }
 
     void Constraints() {
-        CONS(1 <= A && A <= 10);
-        CONS(1 <= B && B <= 10);
+        CONS(valueOf(A).isBetween(1, 10));
+        CONS(valueOf(B).isBetween(1, 10));
     }
 };
 
diff --git a/test/ete/resources/normal/spec.cpp b/test/ete/resources/normal/spec.cpp
index 5c832295..84190499 100644
--- a/test/ete/resources/normal/spec.cpp
+++ b/test/ete/resources/normal/spec.cpp
@@ -22,8 +22,8 @@ class ProblemSpec : public BaseProblemSpec {
     }
 
     void Constraints() {
-        CONS(1 <= A && A <= 10);
-        CONS(1 <= B && B <= 10);
+        CONS(valueOf(A).isBetween(1, 10));
+        CONS(valueOf(B).isBetween(1, 10));
     }
 };
 
diff --git a/test/unit/tcframe/validator/CoreValidatorTests.cpp b/test/unit/tcframe/validator/CoreValidatorTests.cpp
new file mode 100644
index 00000000..5d38541f
--- /dev/null
+++ b/test/unit/tcframe/validator/CoreValidatorTests.cpp
@@ -0,0 +1,21 @@
+#include "gmock/gmock.h"
+
+#include "tcframe/validator/core.hpp"
+
+using ::testing::Eq;
+using ::testing::Test;
+
+namespace tcframe {
+
+class CoreValidatorTests : public Test {};
+
+TEST_F(CoreValidatorTests, valueOf_isBetween) {
+    EXPECT_FALSE(valueOf(5).isBetween(1, 4));
+    EXPECT_FALSE(valueOf(5).isBetween(6, 10));
+    EXPECT_FALSE(valueOf(5).isBetween(100, -100));
+    EXPECT_TRUE(valueOf(5).isBetween(1, 5));
+    EXPECT_TRUE(valueOf(5).isBetween(5, 10));
+    EXPECT_TRUE(valueOf(5).isBetween(0, 10));
+}
+
+}
diff --git a/test/unit/tcframe/validator/NumberValidatorTests.cpp b/test/unit/tcframe/validator/NumberValidatorTests.cpp
deleted file mode 100644
index 9d9bc914..00000000
--- a/test/unit/tcframe/validator/NumberValidatorTests.cpp
+++ /dev/null
@@ -1,21 +0,0 @@
-#include "gmock/gmock.h"
-
-#include "tcframe/validator/number.hpp"
-
-using ::testing::Eq;
-using ::testing::Test;
-
-namespace tcframe {
-
-class NumberValidatorTests : public Test {};
-
-TEST_F(NumberValidatorTests, isBetween) {
-    EXPECT_FALSE(isBetween(5, 1, 4));
-    EXPECT_FALSE(isBetween(5, 6, 10));
-    EXPECT_FALSE(isBetween(5, 100, -100));
-    EXPECT_TRUE(isBetween(5, 1, 5));
-    EXPECT_TRUE(isBetween(5, 5, 10));
-    EXPECT_TRUE(isBetween(5, 0, 10));
-}
-
-}