24 Aug
2008
24 Aug
'08
11:36 a.m.
Am Sonntag, 24. August 2008 17:21 schrieb Yitzchak Gale:
Alfonso Acosta wrote:
I haven't tried to run the code, but my first bet is that, due to the rank-2 polymorphism of ST, you should use parenthesis instead of $ in the case of runST.
Perhaps if Andrew is using an old compiler. That is no longer a problem in recent versions of GHC.
A more basic issue is that fn is in the IO monad, but its use inside the mapM will need it to be in the ST monad.
No, return (fn particle) :: ST s (IO ()) , so that's fine. Indeed, filling in a few dummies, the code compiles with the 6.8 branch.
Regards, Yitz
Cheers, Daniel