On Thu, Feb 16, 2012 at 4:52 PM, Alex Mason
Sounds like it's definitely worth playing with. I would hesitate to use the shootout benchmarks though, simply because anything there is already going to be unpacked to the hilt.
That was the point of number (2) above. By disabling their unpack pragmas through the compiler and measuring the performance, we can simulate a world where people don't write unpack pragmas and then see how much GHC could improve things in such a world. If the gain is large enough we can turn this optimization on and people can waste less time cluttering their code with unpack pragmas! Note that this proposal doesn't but you any new expressive powers. The intention is two-fold: decrease the amount of clutter in Haskell programs and have code written by beginner/intermediate level Haskellers perform better out-of-the-box.
How difficult do you think it would be to implement this in GHC?
Quite easy I think. All the difficulty is in getting good benchmarks. -- Johan