diff --git a/README.md b/README.md
index 936ead0..acbdd6c 100644
--- a/README.md
+++ b/README.md
@@ -97,7 +97,7 @@ assert(val == -3);
 
 It may be helpful to keep in mind that the action behavior is similar to the YACC semantic action model ($$, $1, $2, ...).
 
-In this example, the actions return values. These samentic values will be pushed up to the parent definition which can be referred to in the parent action `[](const vector<Any>& v)`. In other words, when a certain definition has been accepted, we can find all semantic values which are associated with the child definitions in `const vector<Any>& v`. The values are wrapped by peblib::Any class which is like `boost::any`. We can retrieve the value by using `get<T>` method where `T` is the actual type of the value. If no value is returned in an action, an undefined `Any` will be pushed up to the parent. Finally, the resulting value of the root definition is received in the out parameter of `parse` method in the parser. `long val` is the resulting value in this case.
+In this example, the actions return values. These samentic values will be pushed up to the parent definition which can be referred to in the parent action `[](const vector<Any>& v)`. In other words, when a certain definition has been accepted, we can find all semantic values which are associated with the child definitions in `const vector<Any>& v`. The values are wrapped by peglib::Any class which is like `boost::any`. We can retrieve the value by using `get<T>` method where `T` is the actual type of the value. If no value is returned in an action, an undefined `Any` will be pushed up to the parent. Finally, the resulting value of the root definition is received in the out parameter of `parse` method in the parser. `long val` is the resulting value in this case.
 
 Here are available user actions:
 
diff --git a/peglib.h b/peglib.h
index ddf6ad0..39f9bf2 100644
--- a/peglib.h
+++ b/peglib.h
@@ -115,15 +115,24 @@ public:
         return *this;
     }
 
-    operator const std::string&() const {
-        return get<std::string>();
-    }
-
-    operator std::string&() {
-        return get<std::string>();
-    }
-
     // TODO: Add more implecit cast operators
+    operator bool() const { return get<bool>(); }
+    operator char() const { return get<char>(); }
+    operator wchar_t() const { return get<wchar_t>(); }
+    operator char16_t() const { return get<char16_t>(); }
+    operator char32_t() const { return get<char32_t>(); }
+    operator unsigned char() const { return get<unsigned char>(); }
+    operator int() const { return get<int>(); }
+    operator unsigned int() const { return get<unsigned int>(); }
+    operator short() const { return get<short>(); }
+    operator unsigned short() const { return get<unsigned short>(); }
+    operator long() const { return get<long>(); }
+    operator unsigned long() const { return get<unsigned long>(); }
+    operator long long() const { return get<long long>(); }
+    operator unsigned long long() const { return get<unsigned long long>(); }
+    operator float() const { return get<float>(); }
+    operator double() const { return get<double>(); }
+    operator const std::string&() const { return get<std::string>(); }
 
 private:
     struct placeholder {
@@ -189,13 +198,16 @@ public:
 
     //Action(Action&& rhs) : fn_(std::move(rhs.fn_)) {}
 
-    template <typename F, typename std::enable_if<!std::is_pointer<F>::value>::type*& = enabler>
+    template <typename F, typename std::enable_if<!std::is_pointer<F>::value && !std::is_null_pointer<F>::value>::type*& = enabler>
     Action(F fn) : fn_(make_adaptor(fn, &F::operator())) {}
 
     template <typename F, typename std::enable_if<std::is_pointer<F>::value>::type*& = enabler>
     Action(F fn) : fn_(make_adaptor(fn, fn)) {}
 
-    template <typename F, typename std::enable_if<!std::is_pointer<F>::value>::type*& = enabler>
+    template <typename F, typename std::enable_if<std::is_null_pointer<F>::value>::type*& = enabler>
+    Action(F fn) {}
+
+    template <typename F, typename std::enable_if<!std::is_pointer<F>::value && !std::is_null_pointer<F>::value>::type*& = enabler>
     void operator=(F fn) {
         fn_ = make_adaptor(fn, &F::operator());
     }
@@ -205,6 +217,9 @@ public:
         fn_ = make_adaptor(fn, fn);
     }
 
+    template <typename F, typename std::enable_if<std::is_null_pointer<F>::value>::type*& = enabler>
+    void operator=(F fn) {}
+
     operator bool() const {
         return (bool)fn_;
     }
diff --git a/test/test.cc b/test/test.cc
index ba9467a..e4cd902 100644
--- a/test/test.cc
+++ b/test/test.cc
@@ -131,7 +131,7 @@ TEST_CASE("Simple calculator test", "[general]")
 
     parser["Additive"] = {
         // Default action
-        []() {},
+        nullptr,
         // Action for the first choice
         [](const vector<Any>& v) { return v[0].get<int>() + v[1].get<int>(); },
         // Action for the second choice
@@ -139,7 +139,7 @@ TEST_CASE("Simple calculator test", "[general]")
     };
 
     parser["Multitive"] = [](const vector<Any>& v) {
-        return v.size() == 1 ? v[0] : v[0].get<int>() * v[1].get<int>();
+        return v.size() == 1 ? int(v[0]) : v[0].get<int>() * v[1].get<int>();
     };
 
     parser["Primary"] = [](const vector<Any>& v) {