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Prettier Concurrency: Purely Functional Concurrent Revisions

Daan Leijen, Sebastian Burckhardt, and Manuel Fahndrich


This article presents an extension to the work of Launchbury and Peyton-Jones on the ST monad. Using a novel model for concurrency, called "concurrent revisions", we show how we can use concurrency together with imperative mutable variables, while still being able to safely convert such computations (in the Rev monad) into pure values again.

In contrast to many other transaction models, like software transactional memory (STM), concurrent revisions never use rollback and always deterministically resolve conflicts. As a consequence, concurrent revisions integrate well with side-effecting I/O operations. Using deterministic conflict resolution, concurrent revisions can deal well with situations where there are many conflicts between different threads that modify a shared data structure. We demonstrate this by describing a concurrent game with conflicting concurrent tasks.


Publication typeInproceedings
Published inHaskell Symposium 2011 (Haskell'11)
AddressTokyo, Japan

Previous versions

Sebastian Burckhardt and Daan Leijen. Semantics of Concurrent Revisions, Springer Verlag, March 2011.

Sebastian Burckhardt, Daan Leijen, and Manuel Fahndrich. Roll Forward, Not Back: A Case for Deterministic Conflict Resolution, March 2011.

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