Re: [Haskell-begin] Exercises for beginners and Natural Tansformations

2008/7/19 Chaddaï Fouché :

2008/7/19 Federico Brubacher :

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One more thing to see if I have the fold thing correct : - foldr is good because it's lazy but is not tail recursive - foldl is tail recursive so less stack space but not lazy so not good on infinite lists - foldl' is a mix of the good thing of both , so it is lazy and tail recusive Am I right ?

No... Did you read the link I gave you ? The explanation there is pretty good. First foldr and foldl are both lazy. foldl' is strict in the accumulator.

Ok, I'm confusing this with another discussion, sorry... ^^ The link I was speaking about is : http://www.haskell.org/haskellwiki/Foldr_Foldl_Foldl%27 (But the things I said about the folds are still true :-) -- Jedaï PS : ajb, thank you for the explanation, it was very clear !