[Haskell-cafe] Clarification on proof section of HS: The Craft
of FP
Henning Thielemann
lemming at henning-thielemann.de
Mon May 2 10:09:10 EDT 2005
On Mon, 2 May 2005, Daniel Carrera wrote:
> Daniel Fischer wrote:
>
>> Both do, but in Explanation 2, you omitted 'finite' a couple of times.
>
> Well, I also omited the word "countable". I figure it's understood since
> computers only deal with finite data. And given an infinite list, any finite
> "head" of it would meet the criteria, so the distinction is moot. Unless
> Haskell has some neat property I am not aware of :-)
If you don't take care you may end up "proving" that e.g.
repeat 1 ++ [0] == repeat 0
because for the first list you can prove that every reachable element is
equal to its neighbour and the "last" element is 0.
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