@Unpublished{concsubstrate07,
   author = {Peng Li and Simon Marlow and Simon {Peyton Jones} and Andrew Tolmach},
   title = {Lightweight concurrency primitives for GHC},
   year = {2007},
   month = {June},
   abstract = {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.
},
   url = {http://www.haskell.org/~simonmar/papers/conc-substrate.pdf},
   doi = {{http://doi.acm.org/10.1145/1291201.1291217}},
   isbn = {{978-1-59593-674-5}},
   pages = {{107--118}},
   location = {{Freiburg, Germany}},
   publisher = {{ACM}},
   note = {Haskell '07: Proceedings of the ACM SIGPLAN workshop on Haskell workshop}
}