| > I thought the "lazy functional languages are great for implicit | > parallelism" thing died out some time ago - at least as far as running | > the programs on conventional hardware is concerned. Some quick thoughts. 1. Like Ben L, I don't believe in totally-automated parallelism from lazy FP. But that doesn't mean that lazy FP is bad for parallel machines. On the contrary, it is *absolutely fantastic* that a program decorated with some parallel strategies (see the paper Ben mentioned http://research.microsoft.com/%7Esimonpj/Papers/strategies.ps.gz) is guaranteed to give the same results on a multiprocessor as on a uni-processor. Adding parallel strategies can't make your program go wrong. 2. One reason that implicitly-parallel FP has never "made it" despite lots of work over the last 20 yrs (!) is that uni-processors have kept getting faster. That has already changed (http://www.gotw.ca/publications/concurrency-ddj.htm). We're going to see multi-processors on a chip, because Intel doesn't know what else to do with their transistors. Getting more performance is going to *require* parallelism, which is a real change; until now, parallel processors kept getting outpaced by next year's sequential ones. 3. Furthermore, if everyone has 10 processors on their desk (because you can't buy a machine with fewer -- I'm speculating a little here) then the utilisation efficiency is less important than it used to be. If you have 10 processors anyway, then a programming system that lets you use 3 with minimal effort would be splendid. Whereas up to today if someone forks out for a 10-node machine they jolly well want to use almost all of those 10. 4. Most parallel-FP implementations thus far have been on distributed memory multiprocessors, connected by LANs or some other switch fabric. In particular, each processor has had a separate heap, which entails lots of marshalling and copying of graph between one heap and another. It's incredibly hard to recover these overheads. The new multi-cores will be much more closely coupled, and can share a common heap, with rather high bandwidth between processors. In short, I think things are changing. Simon