17 Jan
2009
17 Jan
'09
6:58 p.m.
On Sat, 2009-01-17 at 10:44 -0800, Max Rabkin wrote:
This traverses the list three times (reverse, init and last are each linear time): fromListEnd xs = Zipper (reverse $ init xs) (last xs) []
But we only need to do it once: fromListEnd xs = let x:xs' = reverse xs in Zipper xs' x []
I don't *think* this has an effect on strictness/laziness, since both versions are strict in the spine of the list.
Excellent suggestion; your solution is much more readable and faster. I've made the change here: http://hpaste.org/14030#a1 Thanks, Jeff Wheeler