[Haskell-cafe] Reference for technique wanted
greg at gregorycollins.net
Sun Oct 31 19:05:37 EDT 2010
"Richard O'Keefe" <ok at cs.otago.ac.nz> writes:
> There's a long-known technique in functional languages
> [x1,...,xn] => \tail -> x1:...xn:tail
> xs ++ ys => f . g
> xs => f 
> A correspondent mentioned to me that he couldn't find a reference
> to the idea (which I gather he had independently rediscovered).
> I know I've read about it somewhere. Can anyone provide a reference?
They're called difference lists:
They allow O(1) snoc and append. I use them all the time!
Gregory Collins <greg at gregorycollins.net>
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