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APLAS 2020
Mon 30 November - Wed 2 December 2020
Wed 2 Dec 2020 18:30 - 19:00 at online - Semantics Chair(s): Florian Rabe

\emph{Monad algebras}, turning computations over return values into values, are used to resolve algebraic effects invoked by programs (effect handling), whereas \emph{comonad coalgebras}, turning initial states into cocomputations over states, are used to specify production of environments with coalgebraic coeffects (coeffect production). \emph{(Monad-comonad) interaction laws} by Katsumata et al. describe interaction protocols between a computation and a cocomputation. We show that any triple of those tools can be combined into a single algebra handling computations over state predicates. This method yields an isomorphism between the category of interaction laws, and the category of so-called \emph{merge functors} which merge algebras and coalgebras to form combined algebras. In a similar vein, we can combine interaction laws with coalgebras only, retrieving Uustalu’s stateful runners. If instead we combine interaction laws with algebras only, we get a novel concept of continuation-based runners that lift a cocomputation of value predicates to a single predicate on computations of values. We use these notions to study different running examples of interactions of computations and cocomputations.

Wed 2 Dec
Times are displayed in time zone: Osaka, Sapporo, Tokyo change

17:30 - 19:00: SemanticsResearch Papers at online
Chair(s): Florian Rabe University of Erlangen
17:30 - 18:00
Certified Semantics for Relational Programming
Research Papers
Dmitry RozplokhasHigher School of Economics and JetBrains Research, Russia, Andrey VyatkinSaint Petersburg State University, Russia, Dmitri BoulytchevSaint Petersburg State University / JetBrains Research
18:00 - 18:30
An Abstract Machine for Strong Call by Value
Research Papers
Malgorzata BiernackaUniversity of Wroclaw, Dariusz BiernackiUniversity of Wrocław, Witold CharatonikInstitute of Computer Science, University of Wroclaw, Tomasz DrabInstitute of Computer Science, University of Wroclaw
18:30 - 19:00
Algebraic and coalgebraic perspectives on interaction laws
Research Papers
Tarmo UustaluReykjavik University, Niels VoorneveldTallinn University of Technology