3 Jun
2009
3 Jun
'09
11:11 a.m.
On Wed, Jun 3, 2009 at 8:42 AM, Daniel Fischer
Am Mittwoch 03 Juni 2009 06:12:46 schrieb Michael Snoyman:
I made two changes:
1. You had the arguments to M.lookup backwards. 2. lookup does not return any generalized Monad, just Maybe (I think that should be changed).
Data.Map.lookup used to return a value in any monad you wanted, I believe until 6.8 inclusive. I don't think it's going to change again soon.
Is there a reason why it only returns in the Maybe monad? I often times have to write a liftMaybe function to deal with that. Michael