About

I am on the academic job market for 2022 positions.
I am a research associate at University of Cambridge. I finished my Ph.D. in the Programming Languages Group at University of Hong Kong. Before that, I obtained my B.S. (with Honors) from Zhejiang Unversity.
I had the pleasure to work with a lot of amazing people during my Ph.D. journey. Check out my wonderful collaborators!
I am a former research intern at DeepMind London, and a former research intern at the RiSE team at Microsoft Research Redmond, and more previously a software engineer intern at Google Search in New York City.
I am a steering committee member of the Haskell Symposium.

News

• 2021 Oct Will give an invited talk at Workshop on Dependable and Secure Software Systems at ETH. Please consider joining us!

• 2021 Oct Will serve on the program committee of ICFP 2022. Please consider submitting a paper!

• 2021 Sept Will serve on the program committee of TFP 2022. Please consider submitting a paper!

• 2021 Sept New work conditionally accepted at POPL 2022.

• 2021 Aug We will be giving a tutorial on Koka at ICFP 2021. Come and join us if that sounds interesting to you.

• 2021 Aug Haskell Implementors' Workshop 2021 is calling for lightning talks.

• 2021 July Will serve on the program committee of FLOPS 2022. Please consider submitting a paper!

Publications

• Staging with Class
  Ningning Xie, Matthew Pickering, Andres Löh, Nicolas Wu, Jeremy Yallop, Meng Wang
  POPL 2022 [preprint] (conditionally accepted)

• Generalized Evidence Passing for Effect Handlers: Efficient Compilation of Effect Handlers to C
  Ningning Xie, Daan Leijen
  ICFP 2021 [doi] [paper] [technical report] [artifact]

• Perceus: Garbage Free Reference Counting with Reuse
  Ningning Xie*, Alex Reinking*, Leonardo de Moura, Daan Leijen (*Equal contributions)
  PLDI 2021 [doi] [paper] [artifact] [technical report]
  ACM SIGPLAN Distinguished Paper Award

• Effect Handlers in Haskell, Evidently.
  Ningning Xie, Daan Leijen
  Haskell 2020 [doi] [paper] [slides] [Haskell implementation] [eveff on Hackage]

• Row and Bounded Polymorphism via Disjoint Polymorphism.
  Ningning Xie, Bruno C. d. S. Oliveira, Xuan Bi, Tom Schrijvers
  ECOOP 2020 [doi] [paper] [appendix] [Coq proof] [poster]

• Effect Handlers, Evidently.
  Ningning Xie, Jonathan Brachthäuser, Daniel Hillerström, Philipp Schuster, Daan Leijen
  ICFP 2020 [doi] [paper] [slides] [technical report]

• Kind Inference for Datatypes.
  Ningning Xie, Richard A. Eisenberg, Bruno C. d. S. Oliveira
  POPL 2020 [doi] [paper] [slides] [appendix]
  ACM SIGPLAN Distinguished Paper Award

• Consistent Subtyping for All.
  Ningning Xie, Xuan Bi, Bruno C. d. S. Oliveira, Tom Schrijvers
  ACM Transactions on Programming Languages and Systems 2020
  [doi] [paper] [Coq proof, Haskell implementation]

• Distributive Disjoint Polymorphism for Compositional Programming.
  Xuan Bi, Ningning Xie, Bruno C. d. S. Oliveira, Tom Schrijvers
  ESOP 2019 [doi] [paper] [slides] [Coq proof, Haskell implementation] [poster]

• Coherence of Type Class Resolution.
  Gert-Jan Bottu, Ningning Xie, Koar Marntirosian, Tom Schrijvers
  ICFP 2019 [doi] [paper] [appendix]

• Consistent Subtyping for All.
  Ningning Xie, Xuan Bi, Bruno C. d. S. Oliveira
  ESOP 2018 [doi] [paper] [Coq proof, Haskell implementation]
  Selected for Special Issue of ACM Transactions on Programming Languages and Systems
  

• Let Arguments Go First.
  Ningning Xie, Bruno C. d. S. Oliveira
  ESOP 2018 [doi] [paper] [appendix] [slides] [Coq proof]

Workshop

• First-class Names for Effect Handlers
  Ningning Xie, Youyou Cong, Daan Leijen
  ACM SIGPLAN Workshop on Higher-Order Programming with Effects 2021 [extended abstract]

• Inferring Datatypes (lightning talk)
  Ningning Xie
  Haskell Implementors' Workshop 2019 [slides]

• Coercion Quantification.
  Ningning Xie, Richard A. Eisenberg
  Haskell Implementors' Workshop 2018 [extended abstract] [slides] [Haskell implementation]

• Towards Unification for Dependent Types.
  Ningning Xie, Bruno C. d. S. Oliveira
  Trends in Functional Programming 2017 [extended abstract] [slides]

Tutorial

• Programming with Effect Handlers and FBIP in Koka
  Daan Leijen, Ningning Xie
  ICFP 2021 Tutorial

Dissertation

• Higher-rank Polymorphism: Type Inference and Extensions.
  Ph.D. Dissertation. [thesis]
  Committee: Bruno Oliveira (advisor), Sergio Lourenco (chair), Zhiyi Huang, Giulio Chiribella, Simon Peyton Jones (external)

Invited Talks

• Efficient Compilation of Algebraic Effect Handlers
  Workshop on Dependable and Secure Software Systems. ETH Zurich. Oct 2021 (upcoming).

• Perceus: Garbage Free Reference Counting with Reuse
  LFCS. The University of Edinburgh. Mar 2021. [slides]

• Type-based Language Design.
  Peking University. Dec 2020.
  JHC. Shanghai Jiao Tong University. Dec 2020.

• Dependent Types in Haskell.
  Hong Kong Functional Programming Meetup. Dec 2018. [code] [slides]

• Consistent Subtyping for All.
  Penn PLClub. University of Pennsylvania. May 2018. [slides]

Service

• Steering Committee: Haskell Symposium (2020 - 2023).
• Program Chair: Haskell Implementor's Workshop 2021.
• Program Committee: Haskell Implementors' Workshop 2019. Haskell 2019. PADL 2021. FLOPS 2022. TFP 2022. ICFP 2022.
• Artifact Evaluation Committee: ICFP 2019. PLDI 2020.
• Sub-Reviewer: APLAS 2016, 2017. ESOP 2017. FLOPS 2018. ECOOP 2019. ICFP 2019.
• Student Volunteer: APSys 2016. PLDI 2018. ICFP 2018. ETAPS 2019.

Mentoring

• PLMW@POPL 2021. Mentor.
• PLMW@SPLASH 2020. Mentor.

Teaching

• Instructor. Haskell 101. Google, New York City. November 2019.
• Teaching Assistant. Principles of Programming Languages. The University of Hong Kong. Spring 2019.
• Teaching Assistant. Functional Programming. The University of Hong Kong. Fall 2017.

Misc

• Literature Review of GHC Core. June 2018.
• I was a funded participant of DeepSpec Summer School 2017.
• Software Foundations, Chinese edition.