Lars Birkedal receives Test of Time Award at ICFP 2026
Ten years after its publication, the paper Higher-Order Ghost State has received the ICFP 2026 Test of Time Award in recognition of its lasting impact on programming languages research. Professor Lars Birkedal received the award at the ACM SIGPLAN International Conference on Functional Programming (ICFP) 2026.
Published at ICFP in 2016, the paper introduced key theoretical foundations that have become an essential part of the Iris program logic framework, which is widely used for reasoning about the correctness and safety of modern software systems. Read Higher-Order Ghost State here: https://iris-project.org/pdfs/2016-icfp-iris2-final.pdf
The award recognises research that has stood the test of time and continues to shape its field a decade after publication. According to the award citation, Higher-Order Ghost State represents "a major milestone for the widely used Iris program logic framework" and has had significant influence on both academic research and industrial applications.
Today, Iris is used by researchers around the world, and more than 150 research papers have built on the framework. Its influence is evident in the numerous papers presented at leading programming languages conferences in 2026 that rely on the ideas introduced in the award-winning work.
The paper was co-authored by Ralf Jung, Robbert Krebbers, Lars Birkedal, and Derek Dreyer.
The Test of Time award was presented at ICFP 2026, which took place in Indianapolis, Indiana, from 24–29 August.