Jeremy Siek is an Associate Professor of Computer Science in the School of Informatics and Computing at Indiana University. Jeremy teaches courses in programming, programming languages, compilers, logic, and other areas of computer science. Jeremy designs new language features to help programmers create and use software libraries and domain-specific languages, especially generic and high-performance ones. In particular, with Walid Taha, Jeremy invented the gradual typing approach to mixing static and dynamic type checking within the same language. Prior to that, Jeremy co-authored the Boost Graph Library and attempted to add concepts to C++. Jeremy is a member of the Center for Programming Systems at IU and Jeremy is an Advocate for gender equity.

Email:, Office: Luddy Hall 3016, Blog, Twitter, CV, Calendar

Technology Transfer

I’ve been fortunate to see some of my ideas get used in the software industry:

  • Facebook has added gradual typing to PHP. See the article in Wired magazine.
    Facebook has also created Flow, a static type checker for JavaScript.
  • Microsoft created a gradually-typed dialect of JavaScript, called TypeScript.
  • The implicits feature of Scala was inspired by my work on concepts for C++.


My group’s research is currently funded by the following sponsors.

Thank you!

Recent Papers and Talks

The full list is available on Google Scholar and DBLP.

  • Toward Efficient Gradual Typing for Structural Types via Coercions, Andre Kuhlenschmidt, Deyaaeldeen Almahallawi, and Jeremy G. Siek. In submission draft. Updated version of below arXiv draft. Adds new performance results but narrows the paper by removing monotonic references.
  • The State of the Art in Gradual Typing,
    Talk at the CS Colloquium, Indiana University. slides
  • Intersection Types, Sub-formula Property, and the Functional Character of the Lambda Calculus, Talk at IU CPS Meeting slides.
  • Modeling the Functional Character of the Lambda Calculus,
    Jeremy G. Siek. Isabelle document available here. Also see this
    blog post.
  • Efficient Gradual Typing, Andre Kuhlenschmidt, Deyaaeldeen Almahallawi, and Jeremy G. Siek. Pre-print on arXiv.
  • Back to the Future with Denotational Semantics.
    Talk at Off the Beaten Track, Jan. 2018. slides.
  • Theorems for Free for Free: Parametricity, With and Without Types. Amal Ahmed, Dustin Jamner, Jeremy G. Siek, and Philip Wadler. In ICFP 2017. pdf
  • Revisiting Elementary Denotational Semantics. Available on arXiv and in submission, Isabelle mechanization.
  • State of the Art in Gradual Typing. Tutorial at POPL 2017. pdf


Previous courses at Univ. of Colorado:

CS MS Student Advising

I am available for walk-in advising in my office (Luddy 3016) on every Monday and Friday at 11AM-noon during the Spring 2018 semester. If you have a question about fulfilling your MS degree requirements, prior to coming to my office, send me an email with a list of your courses organized by how they fulfill the degree requirements. Each course should be listed only a single time. The subject line of the email should be  “CS MS:”. Students who have followed these instructions will be prioritized over students who have not. If you cannot make it to the walk-in time, you may also send me email, and I will read and respond to those emails during the walk-in advising time, but giving priority to students who are there in person.

Information for Students at IU

Students and Post-Doc’s

  1. Michael M. Vitousek (Ph.D. student, Gradual Python, i.e., Reticulated)
  2. Chris Wailes (Ph.D. student, Parallel Programming Languages)
  3. Andre Kuhlenschmidt (Ph.D. student, Compilation of Gradually Typed Languages)
  4. Deyaaeldeen Almahallawi (Ph.D. student, Compilation of Gradually Typed Languages)


  1. Matteo Cimini (Assistant Professor, Univ. of Massachusetts Lowell)
  2. Spenser Bauman (Ph.D. student, Meta-tracing JIT for Racket)
  3. Di Zhong (Undergraduate Research, now Ph.D. student at Northeastern Univ.)
  4. Zeina Migeed (Research co-op from Northeastern, now Ph.D. student at UCLA)
  5. Steev Young (Undergraduate Research in Gradual Typing)
  6. Josie Bealle (Summer Research Opportunity in Computing)
  7. Andre Yuri (Summer Research Opportunity in Computing)
  8. Weiyu Miao (LinkedIn)
    Ph.D. thesis: Reflective Metaprogramming
  9. Geoffrey Belter (Apple)
    Ph.D. thesis: Efficient Generation of Sequences of Dense Linear Algebra through Auto-Tuning
  10. Shashank Bharadwaj (VMware)
  11. Jonathan Turner (Microsoft Typescript => Mozilla Rust)
  12. Erik Silkensen (Flatiron Solutions)
  13. Neelam Agrawal (National Instruments)
  14. Sri Teja Basava (National Instruments)
  15. Ian Karlin (Postdoc at Lawrence Livermore National Laboratory)
  16. Justin Gottschlich (Parallel Computing Lab @ Intel Labs)
    Ph.D. thesis: Invalidating Transactions: Optimizations, Theory, Guarantees, and Unification
  17. Moss Prescott (SlamData)
    M.S. thesis: Speaking for the Trees: a New (Old) Approach to Languages and Syntax
  18. Christopher Schwaab (Ph.D. student at the Univ. of St. Andrews)
  19. David Broman (Assoc. Prof. at KTH Royal Inst. of Tech., Sweden)
    Ph.D. thesis: Meta-Languages and Semantics for Equation-Based Modeling and Simulation