Trait

trait Unsigned(T: Type) {
  assert(IsUnsigned(T.value));
  def asUint64(self): u64 = staticCast(u64, self.value);
}

template <typename T>
struct UnsignedConcept {
  virtual uint64_t asUint64() = 0;
  virtual ~UnsignedConcept() = default;
};
template <typename T>
struct UnsignedModel: public UnsignedConcept<T> {
  T& self;
  UnsignedModel(T& self) : self(self) { static_assert(IsUnsigned<T::ValueT>::value); }
  uint64_t asUint64() override {
    return static_cast<uint64_t>(self.value);
  }
};

impl(T <: U32 | U16 | U8) Unsigned(T) for T {
  def asUint64(self): u64 = staticCast(u64, self);
}

template <typename T, typename Cond>
struct TModel;
template <typename T>
struct TModel<T, std::enable_if<std::is_same<T, uint32_t | uint16_t | uint8_t>>>: public UnsignedConcept<T> {
  T& self;
  UnsignedModel(T& self) : self(self) { }
  uint64_t asUint64() override {
    return static_cast<uint64_t>(self);
  }
};