Added utility functions to check type of script values.

source/mijin/types/script_value.hpp

@@ -85,6 +85,48 @@ public:
 
     std::partial_ordering operator<=>(const ScriptValue& other) const = default;
 
+    [[nodiscard]]
+    bool isUndefined() const noexcept
+    {
+        return std::holds_alternative<UndefinedValue>(base_);
+    }
+    
+    [[nodiscard]]
+    bool isBool() const noexcept
+    {
+        return std::holds_alternative<bool>(base_);
+    }
+    
+    [[nodiscard]]
+    bool isInteger() const noexcept
+    {
+        return std::holds_alternative<script_int_t>(base_);
+    }
+    
+    [[nodiscard]]
+    bool isFloat() const noexcept
+    {
+        return std::holds_alternative<script_float_t>(base_);
+    }
+    
+    [[nodiscard]]
+    bool isString() const noexcept
+    {
+        return std::holds_alternative<std::string>(base_);
+    }
+    
+    [[nodiscard]]
+    bool isArray() const noexcept
+    {
+        return std::holds_alternative<array_t>(base_);
+    }
+
+    [[nodiscard]]
+    bool isMap() const noexcept
+    {
+        return std::holds_alternative<map_t>(base_);
+    }
+
     template<typename TFunction>
     auto visit(TFunction&& function) const
     {