Proposal #3999: Improved folds for Data.Map and Data.IntMap
apfelmus at quantentunnel.de
Fri Apr 23 05:45:09 EDT 2010
Roman Leshchinskiy wrote:
> Hmm, I'd love to see some real-world uses of foldl. I have no idea
> what to optimise it for in vector. Unfortunately, the link above
> doesn't give any examples.
Here a use of foldl from the Haskell98 Prelude:
reverse :: [a] -> [a]
reverse = foldl (flip (:)) 
Basically, foldl is useful if the accumulating parameter uses equal or
more space if evaluated to normal form than the input list.
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