Re: Should foldl' be added to the post-"Plan FTP" Prelude

FTP sets up the expectation that foldl has a specific relationship to foldMap. I suppose you could go against that, and also break any code relying on the current foldl semantics, but I'd personally be very much opposed to that. On Mar 1, 2015 5:13 PM, "Ben Franksen" wrote:

Why not?

David Feuer wrote:

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No, that is not a way now that we have FTP.

On Wed, Feb 25, 2015 at 7:31 PM, Kazu Yamamoto wrote:

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I would love to have foldl' as part of the Prelude. I use it quite frequently and it seems like a beginner trap to have foldl but not foldl' (which is almost always the better choice). I see that foldMap has been added (in addition to all of Monoid and Traversable), why was foldl' left out?

That is one way but I think another way is to make foldl strict:

http://www.well-typed.com/blog/90/

I'm tired of explaining the difference of foldl and foldl' to beginners. :-)

--Kazu

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