Lightweight concurrency primitives for GHC (Peng Li, Simon Marlow, Simon Peyton Jones, Andrew Tolmach) Haskell '07: Proceedings of the ACM SIGPLAN workshop on Haskell workshop, pages 107--118, Freiburg, Germany, ACM, June 2007

The Glasgow Haskell Compiler (GHC) has quite sophisticated support for concurrency in its runtime system, which is written in low-level C code. As GHC evolves, the runtime system becomes increasingly complex, error-prone, difficult to maintain and difficult to add new concurrency features.

This paper presents an alternative approach to implement concurrency in GHC. Rather than hard-wiring all kinds of concurrency features, the runtime system is a thin substrate providing only a small set of concurrency primitives, and the rest of concurrency features are implemented in software libraries written in Haskell. This design improves the safety of concurrency support; it also provides more customizability of concurrency features, as new concurrency features can be developed as Haskell library packages and deployed modularly.