[Haskell-cafe] Thinking about an unlistN

[Philip Neustrom]

I'm no expert, but it looks like the generalization of that would be
some f that took a list:

f :: [a] -> b

so what you'd have is a fold, right?

foldr1 :: (a -> a -> a) -> [a] -> a

Best,
Philip Neustrom

On Sun, Aug 10, 2008 at 11:47 AM, Michael Feathers
<mfeathers at mindspring.com> wrote:
>
> I wrote this function the other day, and I was wondering if I'm missing
> something.. whether there is already a function or idiom around to do this.
>
>
> unlist3 :: (a -> a -> a -> b) -> [a] -> b
> unlist3 f (x:y:z:xs) = f x y z
>
>
> I was also wondering whether the function can be generalized to N or whether
> this is just one of those edges in the type system that you can't abstract
> over.
>
>
> Thanks,
>
> Michael
>
>
>
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