On 12/3/06, John Meacham
On Sat, Dec 02, 2006 at 11:02:28PM +0000, Simon Peyton-Jones wrote: [snip]
| Also, is there a way to do something similar but for 'lazy' rather than | 'seq'? I want something of type | | type World__ = State# RealWorld | | {-# NOINLINE newWorld__ #-} | newWorld__ :: a -> World__ | newWorld__ x = realWord# -- ??? | | except that I need newWorld__ to be lazy in its first argument. I need | to convince the opimizer that the World__ newWorld__ is returning | depends on the argument passed to newWorld__.
I don't understand what you meant here. The definition of newWorld__ that you give is, of course, lazy in x.
it is getting type 'Absent' assigned to it by the demand analysis, I want it to be lazy (and not strict)
3 newWorld__ :: a -> World__ {- Arity: 1 HasNoCafRefs Strictness: A -}
Well, yeah, that's because it *is* absent. If you want to convince the demand analyzer that it isn't, then use x somewhere on the right-hand side of the definition of newWorld__. Maybe I could be more helpful if I knew what you were really trying to do here? (My best guess is that you're trying to implement your own IO monad, which really shouldn't be possible AFAIK unless there's something seriously wrong with GHC that I don't know about. Unless you use The Function That Shall Not Be Named.) Cheers, Kirsten -- Kirsten Chevalier* chevalier@alum.wellesley.edu *Often in error, never in doubt