[Haskell-cafe] Re: [Haskell-beginners] folds -- help!

John Dorsey haskell at colquitt.org
Sat Mar 14 10:03:21 EDT 2009


> That's why I said "for appropriate g and f". But I see that my  
> wording was misleading.

Thanks for following up!  I had thought you were arguing that foldl and
foldr were easily and intuitively interchangeable; they're surely not so
for beginners.

Now I think you're arguing that given strict oplus, each can be generally
expressed in terms of the other, allowing for different space/time

Thanks for clarifying.  I should have paid more attention to your
"appropriate g and f" qualifier.


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