KafKa: Gradual Typing for Objects (Artifact)

Authors Benjamin Chung, Paley Li, Francesco Zappa Nardelli, Jan Vitek

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  • 3 pages

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Benjamin Chung
Paley Li
Francesco Zappa Nardelli
Jan Vitek

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Benjamin Chung, Paley Li, Francesco Zappa Nardelli, and Jan Vitek. KafKa: Gradual Typing for Objects (Artifact). In Special Issue of the 32nd European Conference on Object-Oriented Programming (ECOOP 2018). Dagstuhl Artifacts Series (DARTS), Volume 4, Issue 3, pp. 10:1-10:3, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)



A wide range of gradual type systems have been proposed, providing many languages with the ability to mix typed and untyped code. However, hiding under language details, these gradual type systems have fundamentally different ideas of what it means to be typed. In this paper, we show that four of the most common gradual type systems provide distinct guarantees, and we give a formal framework for comparing gradual type systems for object-oriented languages. First, we show that the different gradual type systems are practically distinguishable via a three-part litmus test. Then, we present a formal framework for defining and comparing gradual type systems. Within this framework, different gradual type systems become translations between a common source and target language, allowing for direct comparison of semantics and guarantees.
  • Gradual typing
  • object-orientation
  • language design
  • type systems


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  1. Timothy Jones and David J. Pearce. A mechanical soundness proof for subtyping over recursive types. In Proceedings of the 18th Workshop on Formal Techniques for Java-like Programs, FTfJP'16, pages 1:1-1:6, New York, NY, USA, 2016. ACM. URL: http://doi.acm.org/10.1145/2955811.2955812, URL: http://dx.doi.org/10.1145/2955811.2955812.