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

[John Dorsey]

Adrian,

> 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
complexity.

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

Cheers,
John