Is there a collection of laws associated with the Foldable class? Or for
Traversable? - Conal
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On Fri, Jul 29, 2011 at 1:15 PM, Conal Elliott co...@conal.net wrote:
Is there a collection of laws associated with the Foldable class? Or for
Traversable? - Conal
Judging by the documentation in the source, I think all the laws are in
terms of 'toList'...
On Fri, 29 Jul 2011, Conal Elliott wrote:
Is there a collection of laws associated with the Foldable class? Or for
Traversable? - Conal
Recently I asked the same question:
http://www.haskell.org/pipermail/libraries/2011-June/016429.html
and got the answer:
Hi,
On Jul 29, 2011, at 10:15 PM, Conal Elliott wrote:
Is there a collection of laws associated with the Foldable class? Or for
Traversable? - Conal
if you are not aware of The essence of the Iterator pattern by Jeremy Gibbons
and Bruno Oliveira
http://www.cs.ox.ac.uk/jeremy.gibbons/publications/iterator.pdf
Interesting. However I don't understand why the instance in Section
5.5 is not already forbidden by the purity law
traverse pure = pure
and a 'no duplication' constraint would be necessary. For example:
traverse Id
On Jul 30, 2011, at 12:40 AM, Sebastian Fischer wrote:
Interesting. However I don't understand why the instance in Section
5.5 is not already forbidden by the purity law
traverse pure = pure
and a 'no duplication' constraint would be necessary. For example:
traverse Id [1,2,3] =
What am I missing?
I suspect you missed the use of const
Doh! I completely overlooked that it's about duplication of *effects*.
Thanks,
Sebastian
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