[Haskell-cafe] Decision procedure for foldr/foldl/foldl'?

David Fox ddssff at gmail.com
Mon Nov 21 18:26:59 CET 2011

On Mon, Nov 21, 2011 at 4:44 AM, Jerzy Karczmarczuk
<jerzy.karczmarczuk at unicaen.fr> wrote:

> In general, sorry for the cynism, but when I read:
> "There are times when I would like to find out which to use in the quickest
> way possible, rather than reading a long explanation of why each one behaves
> the way it does" of David Fox, I compare it with a question of a young army
> officer, addressed to his elders:
> "Tell me how to win the war in the quickest way possible, rather than boring
> me with the explanations behind all those complicated strategies".

I'm not trying to avoid learning the differences between the different
folds, but I am looking for a mnemonic device that will allow me to
proceed more quickly towards my goal.  My ultimate goal is to write
software, not to understand folds.   Just as it is inappropriate for a
young officer to even contemplate an overall strategy for winning the
war, it would be inappropriate for a general to spend more time than
necessary on the minute details of military tactics, as vital as they

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