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Is the "parallelism" section theoretical, or you can get the Haskell compiler to actually generate multi-core code automatically?

• dons 18y ago
  No, its not theoretical. However, do not assume the Haskell compiler automatically parallelises arbitrary non-parallel code. That's simply not possible to do well, and is really a dead end. What GHC does do is semi-implicit multicore parallelism for particular subsets of the language. The GHC runtime is a parallel runtime supporting a range of parallel abstractions from semi-implicit parallelism to explicit task parallelism, in a three level hierarchy of OS threads -> Haskell lightweight threads -> fine grained thread sparks. The most automated mechanisms are: * thread sparks - you hint which code to run in parallel with `par`, and the runtime uses that hint to parallelise your code, distributing it across cores. * data parallel arrays - if your algorithm is expressible as an array program, use DPH and the array operations will be automatically parallelised (alpha!) To more explicit paralelism with: * threads * transactional memory * mvars * message passing An example of the semi-implicit multicore parallelism is given in the "Haskell in 5 minutes" tutorial here: http://haskell.org/haskellwiki/Haskell_in_5_steps#Write_your_first_parallel_Haskell_program http://haskell.org/haskellwiki/Haskell_in_5_steps#Write_your...