@misc{zhu-2020-retentive,
  author = {Zirun Zhu and Zhixuan Yang and Hsiang-Shang Ko and Zhenjiang Hu},
  title = {Retentive Lenses},
  year = {2020},
  month = {1},
  eprint = {2001.02031},
  archiveprefix = {arXiv}
}