
Foldr - mnemonic - eru
http://foldr.com/
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nickb
I guess a short explanation is in order. foldr/foldl are folding or reduction
operations. Heard of MapReduce? Well, fold is the reduction part (foldl
specifically). It takes a list, function, and an accumulator and returns a
list and the final accumulator value as a result. Pretty much every functional
language has one and foldr/foldl names come from S/ML and later from Haskell.

You can see an example here:
<http://www.cse.unsw.edu.au/~en1000/haskell/hof.html> The difference between
foldr and foldl is how the list is processed and in the final list (left to
right or right to left) so depending on what your function is, order does
matter. Also, foldr is not tail recursive so it can't be optimized nicely.

These sorts of constructs are coming back to forefront of computing since they
offer us a very efficient way to do distributed computing. I use MR all the
time these days to deal with large data sets.

~~~
lpgauth
That's weird.. I just had an SML class and we never learned it was call
folding... It was just being recursive on a list.

Also, the way the website is made the list seems to be infinite (stream) which
is impossible in SML only in Haskell.

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bayleo
Fess up, you found this while searching for a domain for a prospective file-
hosting site you're working on, huh eru? :)

~~~
eru
Not that glamorous.

I actually use it for reminding me which one is foldr and which is foldl in
Haskell. I always forget.

I can not remember how I found it originally, though. Perhaps via Lambda the
Ultimate.

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eru
You may have guessed that there is also foldl.com

~~~
lpgauth
I might be hung over right now but I don't get it?

~~~
khafra
Functional humor.

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mojuba
Brilliant... and what a waste of such a nice domain name!

~~~
1gor
fondlr.com is still available...

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LogicHoleFlaw
Personally I always liked:

<http://tabularasa.org/>

~~~
eru
You may want to join <http://www.this-page-intentionally-left-blank.org/>

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michael_dorfman
Effing brilliant. I wish I had thought of this...

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albertcardona
The script fascinated me so much that I missed completely the fact that the
page _does_ have a body, which explains the mistery. Awesome.

