Section: New Results

Dataflow-explicit futures

Participants : Ludovic Henrio, Matthieu Moy, Amaury Maillé.

A future is a place-holder for a value being computed, and we generally say that a future is resolved when the associated value is computed. In existing languages futures are either implicit, if there is no syntactic or typing distinction between futures and non-future values, or explicit when futures are typed by a parametric type and dedicated functions exist for manipulating futures. We defined a new form of future, named data-flow explicit futures [43], with specific typing rules that do not use classical parametric types. The new futures allow at the same time code reuse and the possibility for recursive functions to return futures like with implicit futures, and let the programmer declare which values are futures and where synchronisation occurs, like with explicit futures. We prove that the obtained programming model is as expressive as implicit futures but exhibits a different behaviour compared to explicit futures. The current status of this work is the following:

• With collaborators from University of Uppsala and University of Oslo we worked on the design of programming constructs mixing implicit and dataflow-explicit futures (DeF). This has been published in ECOOP 2019 [10].

• Amaury Maillé did his internship in the Cash team (advised by Matthieu Moy and Ludovic Henrio), he worked on an implementation of DeF in the Encore language. This raised a difficulty regarding the interaction of DeF with generic types that has been partially solved. Now we need to generalize our approach to completely solve the issue.