text: #pragma once
  
  #include "cell.hpp"
  #include "environment.hpp"
  #include "value.hpp"
  
  namespace oqtopus {
    ValuePtr eval(ValuePtr args, Environment& env);
  
    class EvalError : public OvingtonRuntimeError {
    public:
      EvalError() :
        OvingtonRuntimeError("eval error") {}
  
      EvalError(std::string what) :
        OvingtonRuntimeError("eval error: " + what) {}
    };
  }
  