On Thu, Dec 24, 2009 at 10:09 AM, Tom Davie
The mergesort example given here has a rather nasty problem – it creates sparks for mergeing the two lists at the same time as it creates the lists, so there's always at least one task blocking waiting for it's producers.
Don't worry too much about this thread, here is why : - Jon Harrop is definitely not a beginner in Haskell land and has no business asking this question on this list - Jon Harrop is very well known on established functional programming mailing lists and forum as a very disagreeable troll (not only on Haskell). He love to trash whatever language hasn't his favours at the moment (I think right now he likes F#, which is a very interesting language nonetheless). - He apparently made an effort to include approximately all elements that could hurt Haskell reputation in this thoughtful gift to the community in this Christmas period : ** As you pointed the initial code he chose doesn't parallelize very well basically ** He tried to compile it with GHC 6.8 which was an important step towards better internals to handle parallelism in GHC but was also a time of big upheaval in this field and so not as stable as one could wish. ** He then installed GHC 6.10 and did not even clean up his previous compilations attempts before declaring that it didn't work (the error message he cited is usually observed when GHC encounters an interface file created by a previous version of GHC or on another architecture) at all without testing on some other clean sources. ** He then apparently decided that using a binary package for the 6.12 version was beneath its dignity and went on to install it from source (generally not recommended except for GHC developers that needs to work on the code or for port to unusual architectures) and claimed that there was a "circularity problem" since its 6.10 could not compile it (which it obviously could, as he discovered and qualified as "miraculous", not even considering that he had a working 6.8 before). I could choose to believe that Harrop really is as incompetent as he sounds and really did encounter all those problems (which are all possibles if unlikely to be met in quick succession) but the simple fact that he decided to post this message on the Haskell-Beginner list instead of the Haskell-cafe list where he's already well known and an occasional poster makes it that much more unlikely. The other interpretation is that JdH is up to his usual tricks, just sinking to a new low by posting in a venue where he's less likely to be recognized and more likely to worry unwary would-be-haskell-beginners. Merry Christmas ! -- Jedaï