Initial work on standard library

src/Evaluator/EvalValues/EvalValueHelper.hpp

@@ -49,7 +49,7 @@ namespace Porygon::Evaluation{
             return new BooleanEvalValue(b);
         }
         static EvalValue* Create(const string& s){
-            return new StringEvalValue(Utilities::StringUtils::StringToU16String(s));
+            return new StringEvalValue(Utilities::StringUtils::ToUTF8(s));
         }
         static EvalValue* Create(u16string s){
             return new StringEvalValue(std::move(s));

src/Evaluator/EvalValues/NilEvalValue.hpp

@@ -0,0 +1,25 @@
+#ifndef PORYGONLANG_NILEVALVALUE_HPP
+#define PORYGONLANG_NILEVALVALUE_HPP
+
+#include "EvalValue.hpp"
+
+namespace Porygon::Evaluation{
+    class NilEvalValue : public EvalValue{
+        const TypeClass GetTypeClass() const final{
+            return TypeClass ::Nil;
+        }
+        const bool operator==(EvalValue *b) const final{
+            return b->GetTypeClass() == TypeClass ::Nil;
+        }
+
+        const shared_ptr<EvalValue> Clone() const final{
+            return make_shared<NilEvalValue>();
+        }
+
+        const std::size_t GetHashCode() const final{
+            return 0;
+        }
+    };
+}
+
+#endif //PORYGONLANG_NILEVALVALUE_HPP