Experimenting with graded monads:
certified grading-based program transformationsTalvik, Tõnn; Uustalu, Tarmo24th International Conference on Types for Proofs and Programs : TYPES 2018, Braga, Portugal, 18-21 June, 2018 : abstracts2018 / p. 82-83 https://types2018.projj.eu/book-of-abstracts/