[Haskell-cafe] Data structure containing elements which are instances of the same type class

[wren ng thornton]

On 8/15/12 2:55 PM, Albert Y. C. Lai wrote:
> On 12-08-15 03:20 AM, wren ng thornton wrote:
>> (forall a. P(a)) -> Q <=> exists a. (P(a) -> Q)
>
> For example:
>
> A. (forall p. p drinks) -> (everyone drinks)
> B. exists p. ((p drinks) -> (everyone drinks))
>
> In a recent poll, 100% of respondents think A true, 90% of them think B
> paradoxical, and 40% of them have not heard of the Smullyan drinking
> paradox.

:)

Though bear in mind we're discussing second-order quantification here, 
not first-order.

-- 
Live well,
~wren